* [PATCH 1/2] powerpc/vdso64: Coarse timer support preparatory patch
@ 2017-09-18 9:23 Santosh Sivaraj
2017-09-18 9:23 ` [PATCH 2/2] powerpc/vdso64: Add support for CLOCK_{REALTIME/MONOTONIC}_COARSE Santosh Sivaraj
2017-10-06 9:03 ` [PATCH 1/2] powerpc/vdso64: Coarse timer support preparatory patch Naveen N. Rao
0 siblings, 2 replies; 15+ messages in thread
From: Santosh Sivaraj @ 2017-09-18 9:23 UTC (permalink / raw)
To: linuxppc-dev, Naveen N. Rao
Cc: Michael Ellerman, John Stultz, Thomas Gleixner,
Frederic Weisbecker, Srikar Dronamraju
Reorganize code to make it easy to introduce CLOCK_REALTIME_COARSE and
CLOCK_MONOTONIC_COARSE timer support.
Signed-off-by: Santosh Sivaraj <santosh@fossix.org>
---
arch/powerpc/kernel/vdso64/gettimeofday.S | 14 ++++++++------
1 file changed, 8 insertions(+), 6 deletions(-)
diff --git a/arch/powerpc/kernel/vdso64/gettimeofday.S b/arch/powerpc/kernel/vdso64/gettimeofday.S
index 382021324883..a0b4943811db 100644
--- a/arch/powerpc/kernel/vdso64/gettimeofday.S
+++ b/arch/powerpc/kernel/vdso64/gettimeofday.S
@@ -60,18 +60,20 @@ V_FUNCTION_END(__kernel_gettimeofday)
*/
V_FUNCTION_BEGIN(__kernel_clock_gettime)
.cfi_startproc
+ mr r11,r4 /* r11 saves tp */
+ mflr r12 /* r12 saves lr */
+ lis r7,NSEC_PER_SEC@h /* want nanoseconds */
+ ori r7,r7,NSEC_PER_SEC@l
+
/* Check for supported clock IDs */
cmpwi cr0,r3,CLOCK_REALTIME
cmpwi cr1,r3,CLOCK_MONOTONIC
cror cr0*4+eq,cr0*4+eq,cr1*4+eq
- bne cr0,99f
+ beq cr0,49f
- mflr r12 /* r12 saves lr */
+ b 99f /* Fallback to syscall */
.cfi_register lr,r12
- mr r11,r4 /* r11 saves tp */
- bl V_LOCAL_FUNC(__get_datapage) /* get data page */
- lis r7,NSEC_PER_SEC@h /* want nanoseconds */
- ori r7,r7,NSEC_PER_SEC@l
+49: bl V_LOCAL_FUNC(__get_datapage) /* get data page */
50: bl V_LOCAL_FUNC(__do_get_tspec) /* get time from tb & kernel */
bne cr1,80f /* if not monotonic, all done */
--
2.13.5
^ permalink raw reply related [flat|nested] 15+ messages in thread* [PATCH 2/2] powerpc/vdso64: Add support for CLOCK_{REALTIME/MONOTONIC}_COARSE 2017-09-18 9:23 [PATCH 1/2] powerpc/vdso64: Coarse timer support preparatory patch Santosh Sivaraj @ 2017-09-18 9:23 ` Santosh Sivaraj 2017-10-06 9:28 ` Naveen N. Rao 2017-10-06 11:25 ` Naveen N. Rao 2017-10-06 9:03 ` [PATCH 1/2] powerpc/vdso64: Coarse timer support preparatory patch Naveen N. Rao 1 sibling, 2 replies; 15+ messages in thread From: Santosh Sivaraj @ 2017-09-18 9:23 UTC (permalink / raw) To: linuxppc-dev, Naveen N. Rao Cc: Michael Ellerman, John Stultz, Thomas Gleixner, Frederic Weisbecker, Srikar Dronamraju, Benjamin Herrenschmidt Current vDSO64 implementation does not have support for coarse clocks (CLOCK_MONOTONIC_COARSE, CLOCK_REALTIME_COARSE), for which it falls back to system call, increasing the response time, vDSO implementation reduces the cycle time. Below is a benchmark of the difference in execution time with and without vDSO support. (Non-coarse clocks are also included just for completion) Without vDSO support: -------------------- clock-gettime-realtime: syscall: 172 nsec/call clock-gettime-realtime: libc: 26 nsec/call clock-gettime-realtime: vdso: 21 nsec/call clock-gettime-monotonic: syscall: 170 nsec/call clock-gettime-monotonic: libc: 30 nsec/call clock-gettime-monotonic: vdso: 24 nsec/call clock-gettime-realtime-coarse: syscall: 153 nsec/call clock-gettime-realtime-coarse: libc: 15 nsec/call clock-gettime-realtime-coarse: vdso: 9 nsec/call clock-gettime-monotonic-coarse: syscall: 167 nsec/call clock-gettime-monotonic-coarse: libc: 15 nsec/call clock-gettime-monotonic-coarse: vdso: 11 nsec/call CC: Benjamin Herrenschmidt <benh@kernel.crashing.org> Signed-off-by: Santosh Sivaraj <santosh@fossix.org> --- arch/powerpc/kernel/asm-offsets.c | 2 ++ arch/powerpc/kernel/vdso64/gettimeofday.S | 56 +++++++++++++++++++++++++++++++ 2 files changed, 58 insertions(+) diff --git a/arch/powerpc/kernel/asm-offsets.c b/arch/powerpc/kernel/asm-offsets.c index 8cfb20e38cfe..b55c68c54dc1 100644 --- a/arch/powerpc/kernel/asm-offsets.c +++ b/arch/powerpc/kernel/asm-offsets.c @@ -396,6 +396,8 @@ int main(void) /* Other bits used by the vdso */ DEFINE(CLOCK_REALTIME, CLOCK_REALTIME); DEFINE(CLOCK_MONOTONIC, CLOCK_MONOTONIC); + DEFINE(CLOCK_REALTIME_COARSE, CLOCK_REALTIME_COARSE); + DEFINE(CLOCK_MONOTONIC_COARSE, CLOCK_MONOTONIC_COARSE); DEFINE(NSEC_PER_SEC, NSEC_PER_SEC); DEFINE(CLOCK_REALTIME_RES, MONOTONIC_RES_NSEC); diff --git a/arch/powerpc/kernel/vdso64/gettimeofday.S b/arch/powerpc/kernel/vdso64/gettimeofday.S index a0b4943811db..bae197a81add 100644 --- a/arch/powerpc/kernel/vdso64/gettimeofday.S +++ b/arch/powerpc/kernel/vdso64/gettimeofday.S @@ -71,6 +71,11 @@ V_FUNCTION_BEGIN(__kernel_clock_gettime) cror cr0*4+eq,cr0*4+eq,cr1*4+eq beq cr0,49f + cmpwi cr0,r3,CLOCK_REALTIME_COARSE + cmpwi cr1,r3,CLOCK_MONOTONIC_COARSE + cror cr0*4+eq,cr0*4+eq,cr1*4+eq + beq cr0,65f + b 99f /* Fallback to syscall */ .cfi_register lr,r12 49: bl V_LOCAL_FUNC(__get_datapage) /* get data page */ @@ -112,6 +117,57 @@ V_FUNCTION_BEGIN(__kernel_clock_gettime) 1: bge cr1,80f addi r4,r4,-1 add r5,r5,r7 + b 80f + + /* + * For coarse clocks we get data directly from the vdso data page, so + * we don't need to call __do_get_tspec, but we still need to do the + * counter trick. + */ +65: bl V_LOCAL_FUNC(__get_datapage) /* get data page */ +70: ld r8,CFG_TB_UPDATE_COUNT(r3) + andi. r0,r8,1 /* pending update ? loop */ + bne- 70b + xor r0,r8,r8 /* create dependency */ + add r3,r3,r0 + + /* + * CLOCK_REALTIME_COARSE, below values are needed for MONOTONIC_COARSE + * too + */ + ld r4,STAMP_XTIME+TSPC64_TV_SEC(r3) + ld r5,STAMP_XTIME+TSPC64_TV_NSEC(r3) + bne cr1,78f + + /* CLOCK_MONOTONIC_COARSE */ + lwa r6,WTOM_CLOCK_SEC(r3) + lwa r9,WTOM_CLOCK_NSEC(r3) + + /* check if counter has updated */ +78: or r0,r6,r9 + xor r0,r0,r0 + add r3,r3,r0 + ld r0,CFG_TB_UPDATE_COUNT(r3) + cmpld cr0,r0,r8 /* check if updated */ + bne- 70b + + /* Counter has not updated, so continue calculating proper values for + * sec and nsec if monotonic coarse, or just return with the proper + * values for realtime. + */ + bne cr1,80f + + /* Add wall->monotonic offset and check for overflow or underflow */ + add r4,r4,r6 + add r5,r5,r9 + cmpd cr0,r5,r7 + cmpdi cr1,r5,0 + blt 79f + subf r5,r7,r5 + addi r4,r4,1 +79: bge cr1,80f + addi r4,r4,-1 + add r5,r5,r7 80: std r4,TSPC64_TV_SEC(r11) std r5,TSPC64_TV_NSEC(r11) -- 2.13.5 ^ permalink raw reply related [flat|nested] 15+ messages in thread
* Re: [PATCH 2/2] powerpc/vdso64: Add support for CLOCK_{REALTIME/MONOTONIC}_COARSE 2017-09-18 9:23 ` [PATCH 2/2] powerpc/vdso64: Add support for CLOCK_{REALTIME/MONOTONIC}_COARSE Santosh Sivaraj @ 2017-10-06 9:28 ` Naveen N. Rao 2017-10-09 6:27 ` Santosh Sivaraj 2017-10-06 11:25 ` Naveen N. Rao 1 sibling, 1 reply; 15+ messages in thread From: Naveen N. Rao @ 2017-10-06 9:28 UTC (permalink / raw) To: Santosh Sivaraj Cc: linuxppc-dev, Michael Ellerman, John Stultz, Thomas Gleixner, Frederic Weisbecker, Srikar Dronamraju, Benjamin Herrenschmidt On 2017/09/18 09:23AM, Santosh Sivaraj wrote: > Current vDSO64 implementation does not have support for coarse clocks > (CLOCK_MONOTONIC_COARSE, CLOCK_REALTIME_COARSE), for which it falls back > to system call, increasing the response time, vDSO implementation reduces > the cycle time. Below is a benchmark of the difference in execution time > with and without vDSO support. > > (Non-coarse clocks are also included just for completion) > > Without vDSO support: > -------------------- > clock-gettime-realtime: syscall: 172 nsec/call > clock-gettime-realtime: libc: 26 nsec/call > clock-gettime-realtime: vdso: 21 nsec/call > clock-gettime-monotonic: syscall: 170 nsec/call > clock-gettime-monotonic: libc: 30 nsec/call > clock-gettime-monotonic: vdso: 24 nsec/call > clock-gettime-realtime-coarse: syscall: 153 nsec/call > clock-gettime-realtime-coarse: libc: 15 nsec/call > clock-gettime-realtime-coarse: vdso: 9 nsec/call > clock-gettime-monotonic-coarse: syscall: 167 nsec/call > clock-gettime-monotonic-coarse: libc: 15 nsec/call > clock-gettime-monotonic-coarse: vdso: 11 nsec/call > > CC: Benjamin Herrenschmidt <benh@kernel.crashing.org> > Signed-off-by: Santosh Sivaraj <santosh@fossix.org> > --- > arch/powerpc/kernel/asm-offsets.c | 2 ++ > arch/powerpc/kernel/vdso64/gettimeofday.S | 56 +++++++++++++++++++++++++++++++ > 2 files changed, 58 insertions(+) > > diff --git a/arch/powerpc/kernel/asm-offsets.c b/arch/powerpc/kernel/asm-offsets.c > index 8cfb20e38cfe..b55c68c54dc1 100644 > --- a/arch/powerpc/kernel/asm-offsets.c > +++ b/arch/powerpc/kernel/asm-offsets.c > @@ -396,6 +396,8 @@ int main(void) > /* Other bits used by the vdso */ > DEFINE(CLOCK_REALTIME, CLOCK_REALTIME); > DEFINE(CLOCK_MONOTONIC, CLOCK_MONOTONIC); > + DEFINE(CLOCK_REALTIME_COARSE, CLOCK_REALTIME_COARSE); > + DEFINE(CLOCK_MONOTONIC_COARSE, CLOCK_MONOTONIC_COARSE); > DEFINE(NSEC_PER_SEC, NSEC_PER_SEC); > DEFINE(CLOCK_REALTIME_RES, MONOTONIC_RES_NSEC); > > diff --git a/arch/powerpc/kernel/vdso64/gettimeofday.S b/arch/powerpc/kernel/vdso64/gettimeofday.S > index a0b4943811db..bae197a81add 100644 > --- a/arch/powerpc/kernel/vdso64/gettimeofday.S > +++ b/arch/powerpc/kernel/vdso64/gettimeofday.S > @@ -71,6 +71,11 @@ V_FUNCTION_BEGIN(__kernel_clock_gettime) > cror cr0*4+eq,cr0*4+eq,cr1*4+eq > beq cr0,49f > > + cmpwi cr0,r3,CLOCK_REALTIME_COARSE > + cmpwi cr1,r3,CLOCK_MONOTONIC_COARSE > + cror cr0*4+eq,cr0*4+eq,cr1*4+eq > + beq cr0,65f If you use cr5-7 here, you should be able to re-organize this to not have to update r4/r11/r12 if we're taking the syscall path. Not necessarily a huge win by itself, but can also help reuse some of the other code between the _COARSE and the regular variants. - Naveen > + > b 99f /* Fallback to syscall */ > .cfi_register lr,r12 > 49: bl V_LOCAL_FUNC(__get_datapage) /* get data page */ > @@ -112,6 +117,57 @@ V_FUNCTION_BEGIN(__kernel_clock_gettime) > 1: bge cr1,80f > addi r4,r4,-1 > add r5,r5,r7 > + b 80f > + > + /* > + * For coarse clocks we get data directly from the vdso data page, so > + * we don't need to call __do_get_tspec, but we still need to do the > + * counter trick. > + */ > +65: bl V_LOCAL_FUNC(__get_datapage) /* get data page */ > +70: ld r8,CFG_TB_UPDATE_COUNT(r3) > + andi. r0,r8,1 /* pending update ? loop */ > + bne- 70b > + xor r0,r8,r8 /* create dependency */ > + add r3,r3,r0 > + > + /* > + * CLOCK_REALTIME_COARSE, below values are needed for MONOTONIC_COARSE > + * too > + */ > + ld r4,STAMP_XTIME+TSPC64_TV_SEC(r3) > + ld r5,STAMP_XTIME+TSPC64_TV_NSEC(r3) > + bne cr1,78f > + > + /* CLOCK_MONOTONIC_COARSE */ > + lwa r6,WTOM_CLOCK_SEC(r3) > + lwa r9,WTOM_CLOCK_NSEC(r3) > + > + /* check if counter has updated */ > +78: or r0,r6,r9 > + xor r0,r0,r0 > + add r3,r3,r0 > + ld r0,CFG_TB_UPDATE_COUNT(r3) > + cmpld cr0,r0,r8 /* check if updated */ > + bne- 70b > + > + /* Counter has not updated, so continue calculating proper values for > + * sec and nsec if monotonic coarse, or just return with the proper > + * values for realtime. > + */ > + bne cr1,80f > + > + /* Add wall->monotonic offset and check for overflow or underflow */ > + add r4,r4,r6 > + add r5,r5,r9 > + cmpd cr0,r5,r7 > + cmpdi cr1,r5,0 > + blt 79f > + subf r5,r7,r5 > + addi r4,r4,1 > +79: bge cr1,80f > + addi r4,r4,-1 > + add r5,r5,r7 > > 80: std r4,TSPC64_TV_SEC(r11) > std r5,TSPC64_TV_NSEC(r11) > -- > 2.13.5 > ^ permalink raw reply [flat|nested] 15+ messages in thread
* Re: [PATCH 2/2] powerpc/vdso64: Add support for CLOCK_{REALTIME/MONOTONIC}_COARSE 2017-10-06 9:28 ` Naveen N. Rao @ 2017-10-09 6:27 ` Santosh Sivaraj 0 siblings, 0 replies; 15+ messages in thread From: Santosh Sivaraj @ 2017-10-09 6:27 UTC (permalink / raw) To: Naveen N. Rao Cc: linuxppc-dev, Michael Ellerman, John Stultz, Thomas Gleixner, Frederic Weisbecker, Srikar Dronamraju, Benjamin Herrenschmidt * Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> wrote (on 2017-10-06 09:28:30 +0000): > On 2017/09/18 09:23AM, Santosh Sivaraj wrote: > > Current vDSO64 implementation does not have support for coarse clocks > > (CLOCK_MONOTONIC_COARSE, CLOCK_REALTIME_COARSE), for which it falls back > > to system call, increasing the response time, vDSO implementation reduces > > the cycle time. Below is a benchmark of the difference in execution time > > with and without vDSO support. > > > > (Non-coarse clocks are also included just for completion) > > > > Without vDSO support: > > -------------------- > > clock-gettime-realtime: syscall: 172 nsec/call > > clock-gettime-realtime: libc: 26 nsec/call > > clock-gettime-realtime: vdso: 21 nsec/call > > clock-gettime-monotonic: syscall: 170 nsec/call > > clock-gettime-monotonic: libc: 30 nsec/call > > clock-gettime-monotonic: vdso: 24 nsec/call > > clock-gettime-realtime-coarse: syscall: 153 nsec/call > > clock-gettime-realtime-coarse: libc: 15 nsec/call > > clock-gettime-realtime-coarse: vdso: 9 nsec/call > > clock-gettime-monotonic-coarse: syscall: 167 nsec/call > > clock-gettime-monotonic-coarse: libc: 15 nsec/call > > clock-gettime-monotonic-coarse: vdso: 11 nsec/call > > > > CC: Benjamin Herrenschmidt <benh@kernel.crashing.org> > > Signed-off-by: Santosh Sivaraj <santosh@fossix.org> > > --- > > arch/powerpc/kernel/asm-offsets.c | 2 ++ > > arch/powerpc/kernel/vdso64/gettimeofday.S | 56 +++++++++++++++++++++++++++++++ > > 2 files changed, 58 insertions(+) > > > > diff --git a/arch/powerpc/kernel/asm-offsets.c b/arch/powerpc/kernel/asm-offsets.c > > index 8cfb20e38cfe..b55c68c54dc1 100644 > > --- a/arch/powerpc/kernel/asm-offsets.c > > +++ b/arch/powerpc/kernel/asm-offsets.c > > @@ -396,6 +396,8 @@ int main(void) > > /* Other bits used by the vdso */ > > DEFINE(CLOCK_REALTIME, CLOCK_REALTIME); > > DEFINE(CLOCK_MONOTONIC, CLOCK_MONOTONIC); > > + DEFINE(CLOCK_REALTIME_COARSE, CLOCK_REALTIME_COARSE); > > + DEFINE(CLOCK_MONOTONIC_COARSE, CLOCK_MONOTONIC_COARSE); > > DEFINE(NSEC_PER_SEC, NSEC_PER_SEC); > > DEFINE(CLOCK_REALTIME_RES, MONOTONIC_RES_NSEC); > > > > diff --git a/arch/powerpc/kernel/vdso64/gettimeofday.S b/arch/powerpc/kernel/vdso64/gettimeofday.S > > index a0b4943811db..bae197a81add 100644 > > --- a/arch/powerpc/kernel/vdso64/gettimeofday.S > > +++ b/arch/powerpc/kernel/vdso64/gettimeofday.S > > @@ -71,6 +71,11 @@ V_FUNCTION_BEGIN(__kernel_clock_gettime) > > cror cr0*4+eq,cr0*4+eq,cr1*4+eq > > beq cr0,49f > > > > + cmpwi cr0,r3,CLOCK_REALTIME_COARSE > > + cmpwi cr1,r3,CLOCK_MONOTONIC_COARSE > > + cror cr0*4+eq,cr0*4+eq,cr1*4+eq > > + beq cr0,65f > > If you use cr5-7 here, you should be able to re-organize this to not > have to update r4/r11/r12 if we're taking the syscall path. Not > necessarily a huge win by itself, but can also help reuse some of the > other code between the _COARSE and the regular variants. > If we are going to use cr5-7, then the first patch is no longer required, we don't have to do a re-org of the intial clock_id checks. I will send the updated patch. Thanks, Santosh > - Naveen > > > + > > b 99f /* Fallback to syscall */ > > .cfi_register lr,r12 > > 49: bl V_LOCAL_FUNC(__get_datapage) /* get data page */ > > @@ -112,6 +117,57 @@ V_FUNCTION_BEGIN(__kernel_clock_gettime) > > 1: bge cr1,80f > > addi r4,r4,-1 > > add r5,r5,r7 > > + b 80f > > + > > + /* > > + * For coarse clocks we get data directly from the vdso data page, so > > + * we don't need to call __do_get_tspec, but we still need to do the > > + * counter trick. > > + */ > > +65: bl V_LOCAL_FUNC(__get_datapage) /* get data page */ > > +70: ld r8,CFG_TB_UPDATE_COUNT(r3) > > + andi. r0,r8,1 /* pending update ? loop */ > > + bne- 70b > > + xor r0,r8,r8 /* create dependency */ > > + add r3,r3,r0 > > + > > + /* > > + * CLOCK_REALTIME_COARSE, below values are needed for MONOTONIC_COARSE > > + * too > > + */ > > + ld r4,STAMP_XTIME+TSPC64_TV_SEC(r3) > > + ld r5,STAMP_XTIME+TSPC64_TV_NSEC(r3) > > + bne cr1,78f > > + > > + /* CLOCK_MONOTONIC_COARSE */ > > + lwa r6,WTOM_CLOCK_SEC(r3) > > + lwa r9,WTOM_CLOCK_NSEC(r3) > > + > > + /* check if counter has updated */ > > +78: or r0,r6,r9 > > + xor r0,r0,r0 > > + add r3,r3,r0 > > + ld r0,CFG_TB_UPDATE_COUNT(r3) > > + cmpld cr0,r0,r8 /* check if updated */ > > + bne- 70b > > + > > + /* Counter has not updated, so continue calculating proper values for > > + * sec and nsec if monotonic coarse, or just return with the proper > > + * values for realtime. > > + */ > > + bne cr1,80f > > + > > + /* Add wall->monotonic offset and check for overflow or underflow */ > > + add r4,r4,r6 > > + add r5,r5,r9 > > + cmpd cr0,r5,r7 > > + cmpdi cr1,r5,0 > > + blt 79f > > + subf r5,r7,r5 > > + addi r4,r4,1 > > +79: bge cr1,80f > > + addi r4,r4,-1 > > + add r5,r5,r7 > > > > 80: std r4,TSPC64_TV_SEC(r11) > > std r5,TSPC64_TV_NSEC(r11) > > -- > > 2.13.5 > > > -- ^ permalink raw reply [flat|nested] 15+ messages in thread
* Re: [PATCH 2/2] powerpc/vdso64: Add support for CLOCK_{REALTIME/MONOTONIC}_COARSE 2017-09-18 9:23 ` [PATCH 2/2] powerpc/vdso64: Add support for CLOCK_{REALTIME/MONOTONIC}_COARSE Santosh Sivaraj 2017-10-06 9:28 ` Naveen N. Rao @ 2017-10-06 11:25 ` Naveen N. Rao 2017-10-09 6:23 ` Santosh Sivaraj 2017-10-09 8:09 ` [PATCH v4] " Santosh Sivaraj 1 sibling, 2 replies; 15+ messages in thread From: Naveen N. Rao @ 2017-10-06 11:25 UTC (permalink / raw) To: Santosh Sivaraj Cc: linuxppc-dev, Michael Ellerman, John Stultz, Thomas Gleixner, Frederic Weisbecker, Srikar Dronamraju, Benjamin Herrenschmidt On 2017/09/18 09:23AM, Santosh Sivaraj wrote: > Current vDSO64 implementation does not have support for coarse clocks > (CLOCK_MONOTONIC_COARSE, CLOCK_REALTIME_COARSE), for which it falls back > to system call, increasing the response time, vDSO implementation reduces > the cycle time. Below is a benchmark of the difference in execution time > with and without vDSO support. > > (Non-coarse clocks are also included just for completion) > > Without vDSO support: > -------------------- > clock-gettime-realtime: syscall: 172 nsec/call > clock-gettime-realtime: libc: 26 nsec/call > clock-gettime-realtime: vdso: 21 nsec/call > clock-gettime-monotonic: syscall: 170 nsec/call > clock-gettime-monotonic: libc: 30 nsec/call > clock-gettime-monotonic: vdso: 24 nsec/call > clock-gettime-realtime-coarse: syscall: 153 nsec/call > clock-gettime-realtime-coarse: libc: 15 nsec/call > clock-gettime-realtime-coarse: vdso: 9 nsec/call > clock-gettime-monotonic-coarse: syscall: 167 nsec/call > clock-gettime-monotonic-coarse: libc: 15 nsec/call > clock-gettime-monotonic-coarse: vdso: 11 nsec/call > > CC: Benjamin Herrenschmidt <benh@kernel.crashing.org> > Signed-off-by: Santosh Sivaraj <santosh@fossix.org> > --- > arch/powerpc/kernel/asm-offsets.c | 2 ++ > arch/powerpc/kernel/vdso64/gettimeofday.S | 56 +++++++++++++++++++++++++++++++ > 2 files changed, 58 insertions(+) > > diff --git a/arch/powerpc/kernel/asm-offsets.c b/arch/powerpc/kernel/asm-offsets.c > index 8cfb20e38cfe..b55c68c54dc1 100644 > --- a/arch/powerpc/kernel/asm-offsets.c > +++ b/arch/powerpc/kernel/asm-offsets.c > @@ -396,6 +396,8 @@ int main(void) > /* Other bits used by the vdso */ > DEFINE(CLOCK_REALTIME, CLOCK_REALTIME); > DEFINE(CLOCK_MONOTONIC, CLOCK_MONOTONIC); > + DEFINE(CLOCK_REALTIME_COARSE, CLOCK_REALTIME_COARSE); > + DEFINE(CLOCK_MONOTONIC_COARSE, CLOCK_MONOTONIC_COARSE); > DEFINE(NSEC_PER_SEC, NSEC_PER_SEC); > DEFINE(CLOCK_REALTIME_RES, MONOTONIC_RES_NSEC); > > diff --git a/arch/powerpc/kernel/vdso64/gettimeofday.S b/arch/powerpc/kernel/vdso64/gettimeofday.S > index a0b4943811db..bae197a81add 100644 > --- a/arch/powerpc/kernel/vdso64/gettimeofday.S > +++ b/arch/powerpc/kernel/vdso64/gettimeofday.S > @@ -71,6 +71,11 @@ V_FUNCTION_BEGIN(__kernel_clock_gettime) > cror cr0*4+eq,cr0*4+eq,cr1*4+eq > beq cr0,49f > > + cmpwi cr0,r3,CLOCK_REALTIME_COARSE > + cmpwi cr1,r3,CLOCK_MONOTONIC_COARSE > + cror cr0*4+eq,cr0*4+eq,cr1*4+eq > + beq cr0,65f > + > b 99f /* Fallback to syscall */ > .cfi_register lr,r12 > 49: bl V_LOCAL_FUNC(__get_datapage) /* get data page */ > @@ -112,6 +117,57 @@ V_FUNCTION_BEGIN(__kernel_clock_gettime) > 1: bge cr1,80f > addi r4,r4,-1 > add r5,r5,r7 > + b 80f > + > + /* > + * For coarse clocks we get data directly from the vdso data page, so > + * we don't need to call __do_get_tspec, but we still need to do the > + * counter trick. > + */ > +65: bl V_LOCAL_FUNC(__get_datapage) /* get data page */ > +70: ld r8,CFG_TB_UPDATE_COUNT(r3) > + andi. r0,r8,1 /* pending update ? loop */ > + bne- 70b > + xor r0,r8,r8 /* create dependency */ > + add r3,r3,r0 > + > + /* > + * CLOCK_REALTIME_COARSE, below values are needed for MONOTONIC_COARSE > + * too > + */ > + ld r4,STAMP_XTIME+TSPC64_TV_SEC(r3) > + ld r5,STAMP_XTIME+TSPC64_TV_NSEC(r3) > + bne cr1,78f > + > + /* CLOCK_MONOTONIC_COARSE */ > + lwa r6,WTOM_CLOCK_SEC(r3) > + lwa r9,WTOM_CLOCK_NSEC(r3) > + > + /* check if counter has updated */ > +78: or r0,r6,r9 > + xor r0,r0,r0 > + add r3,r3,r0 > + ld r0,CFG_TB_UPDATE_COUNT(r3) > + cmpld cr0,r0,r8 /* check if updated */ > + bne- 70b Don't you need a dependency on r4/r5 here for REALTIME_COARSE? Something like: /* check if counter has updated */ or r0,r6,r9 78: or r0,r4,r5 xor r0,r0,r0 > + > + /* Counter has not updated, so continue calculating proper values for > + * sec and nsec if monotonic coarse, or just return with the proper > + * values for realtime. > + */ > + bne cr1,80f > + I think the below hunk can surely be shared across the _COARSE and regular clocks, if not more. - Naveen > + /* Add wall->monotonic offset and check for overflow or underflow */ > + add r4,r4,r6 > + add r5,r5,r9 > + cmpd cr0,r5,r7 > + cmpdi cr1,r5,0 > + blt 79f > + subf r5,r7,r5 > + addi r4,r4,1 > +79: bge cr1,80f > + addi r4,r4,-1 > + add r5,r5,r7 > > 80: std r4,TSPC64_TV_SEC(r11) > std r5,TSPC64_TV_NSEC(r11) > -- > 2.13.5 > ^ permalink raw reply [flat|nested] 15+ messages in thread
* Re: [PATCH 2/2] powerpc/vdso64: Add support for CLOCK_{REALTIME/MONOTONIC}_COARSE 2017-10-06 11:25 ` Naveen N. Rao @ 2017-10-09 6:23 ` Santosh Sivaraj 2017-10-09 8:09 ` [PATCH v4] " Santosh Sivaraj 1 sibling, 0 replies; 15+ messages in thread From: Santosh Sivaraj @ 2017-10-09 6:23 UTC (permalink / raw) To: Naveen N. Rao Cc: linuxppc-dev, Michael Ellerman, John Stultz, Thomas Gleixner, Frederic Weisbecker, Srikar Dronamraju, Benjamin Herrenschmidt * Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> wrote (on 2017-10-06 11:25:28 +0000): > On 2017/09/18 09:23AM, Santosh Sivaraj wrote: > > Current vDSO64 implementation does not have support for coarse clocks > > (CLOCK_MONOTONIC_COARSE, CLOCK_REALTIME_COARSE), for which it falls back > > to system call, increasing the response time, vDSO implementation reduces > > the cycle time. Below is a benchmark of the difference in execution time > > with and without vDSO support. > > > > (Non-coarse clocks are also included just for completion) > > > > Without vDSO support: > > -------------------- > > clock-gettime-realtime: syscall: 172 nsec/call > > clock-gettime-realtime: libc: 26 nsec/call > > clock-gettime-realtime: vdso: 21 nsec/call > > clock-gettime-monotonic: syscall: 170 nsec/call > > clock-gettime-monotonic: libc: 30 nsec/call > > clock-gettime-monotonic: vdso: 24 nsec/call > > clock-gettime-realtime-coarse: syscall: 153 nsec/call > > clock-gettime-realtime-coarse: libc: 15 nsec/call > > clock-gettime-realtime-coarse: vdso: 9 nsec/call > > clock-gettime-monotonic-coarse: syscall: 167 nsec/call > > clock-gettime-monotonic-coarse: libc: 15 nsec/call > > clock-gettime-monotonic-coarse: vdso: 11 nsec/call > > > > CC: Benjamin Herrenschmidt <benh@kernel.crashing.org> > > Signed-off-by: Santosh Sivaraj <santosh@fossix.org> > > --- > > arch/powerpc/kernel/asm-offsets.c | 2 ++ > > arch/powerpc/kernel/vdso64/gettimeofday.S | 56 +++++++++++++++++++++++++++++++ > > 2 files changed, 58 insertions(+) > > > > diff --git a/arch/powerpc/kernel/asm-offsets.c b/arch/powerpc/kernel/asm-offsets.c > > index 8cfb20e38cfe..b55c68c54dc1 100644 > > --- a/arch/powerpc/kernel/asm-offsets.c > > +++ b/arch/powerpc/kernel/asm-offsets.c > > @@ -396,6 +396,8 @@ int main(void) > > /* Other bits used by the vdso */ > > DEFINE(CLOCK_REALTIME, CLOCK_REALTIME); > > DEFINE(CLOCK_MONOTONIC, CLOCK_MONOTONIC); > > + DEFINE(CLOCK_REALTIME_COARSE, CLOCK_REALTIME_COARSE); > > + DEFINE(CLOCK_MONOTONIC_COARSE, CLOCK_MONOTONIC_COARSE); > > DEFINE(NSEC_PER_SEC, NSEC_PER_SEC); > > DEFINE(CLOCK_REALTIME_RES, MONOTONIC_RES_NSEC); > > > > diff --git a/arch/powerpc/kernel/vdso64/gettimeofday.S b/arch/powerpc/kernel/vdso64/gettimeofday.S > > index a0b4943811db..bae197a81add 100644 > > --- a/arch/powerpc/kernel/vdso64/gettimeofday.S > > +++ b/arch/powerpc/kernel/vdso64/gettimeofday.S > > @@ -71,6 +71,11 @@ V_FUNCTION_BEGIN(__kernel_clock_gettime) > > cror cr0*4+eq,cr0*4+eq,cr1*4+eq > > beq cr0,49f > > > > + cmpwi cr0,r3,CLOCK_REALTIME_COARSE > > + cmpwi cr1,r3,CLOCK_MONOTONIC_COARSE > > + cror cr0*4+eq,cr0*4+eq,cr1*4+eq > > + beq cr0,65f > > + > > b 99f /* Fallback to syscall */ > > .cfi_register lr,r12 > > 49: bl V_LOCAL_FUNC(__get_datapage) /* get data page */ > > @@ -112,6 +117,57 @@ V_FUNCTION_BEGIN(__kernel_clock_gettime) > > 1: bge cr1,80f > > addi r4,r4,-1 > > add r5,r5,r7 > > + b 80f > > + > > + /* > > + * For coarse clocks we get data directly from the vdso data page, so > > + * we don't need to call __do_get_tspec, but we still need to do the > > + * counter trick. > > + */ > > +65: bl V_LOCAL_FUNC(__get_datapage) /* get data page */ > > +70: ld r8,CFG_TB_UPDATE_COUNT(r3) > > + andi. r0,r8,1 /* pending update ? loop */ > > + bne- 70b > > + xor r0,r8,r8 /* create dependency */ > > + add r3,r3,r0 > > + > > + /* > > + * CLOCK_REALTIME_COARSE, below values are needed for MONOTONIC_COARSE > > + * too > > + */ > > + ld r4,STAMP_XTIME+TSPC64_TV_SEC(r3) > > + ld r5,STAMP_XTIME+TSPC64_TV_NSEC(r3) > > + bne cr1,78f > > + > > + /* CLOCK_MONOTONIC_COARSE */ > > + lwa r6,WTOM_CLOCK_SEC(r3) > > + lwa r9,WTOM_CLOCK_NSEC(r3) > > + > > + /* check if counter has updated */ > > +78: or r0,r6,r9 > > + xor r0,r0,r0 > > + add r3,r3,r0 > > + ld r0,CFG_TB_UPDATE_COUNT(r3) > > + cmpld cr0,r0,r8 /* check if updated */ > > + bne- 70b > > Don't you need a dependency on r4/r5 here for REALTIME_COARSE? > Something like: > > /* check if counter has updated */ > or r0,r6,r9 > 78: or r0,r4,r5 > xor r0,r0,r0 > Yes, we would need it. Will update in v2. > > + > > + /* Counter has not updated, so continue calculating proper values for > > + * sec and nsec if monotonic coarse, or just return with the proper > > + * values for realtime. > > + */ > > + bne cr1,80f > > + > > I think the below hunk can surely be shared across the _COARSE and > regular clocks, if not more. Yes, except for the label its the same for both monotonic and monotonic_coarse, will update in the next set. Thanks, Santosh > > - Naveen > > > + /* Add wall->monotonic offset and check for overflow or underflow */ > > + add r4,r4,r6 > > + add r5,r5,r9 > > + cmpd cr0,r5,r7 > > + cmpdi cr1,r5,0 > > + blt 79f > > + subf r5,r7,r5 > > + addi r4,r4,1 > > +79: bge cr1,80f > > + addi r4,r4,-1 > > + add r5,r5,r7 > > > > 80: std r4,TSPC64_TV_SEC(r11) > > std r5,TSPC64_TV_NSEC(r11) > > -- > > 2.13.5 > > > -- ^ permalink raw reply [flat|nested] 15+ messages in thread
* [PATCH v4] powerpc/vdso64: Add support for CLOCK_{REALTIME/MONOTONIC}_COARSE 2017-10-06 11:25 ` Naveen N. Rao 2017-10-09 6:23 ` Santosh Sivaraj @ 2017-10-09 8:09 ` Santosh Sivaraj 2017-10-09 10:39 ` Naveen N. Rao 1 sibling, 1 reply; 15+ messages in thread From: Santosh Sivaraj @ 2017-10-09 8:09 UTC (permalink / raw) To: linuxppc-dev Cc: Michael Ellerman, John Stultz, Thomas Gleixner, Frederic Weisbecker, Naveen N. Rao, Srikar Dronamraju, Benjamin Herrenschmidt Current vDSO64 implementation does not have support for coarse clocks (CLOCK_MONOTONIC_COARSE, CLOCK_REALTIME_COARSE), for which it falls back to system call, increasing the response time, vDSO implementation reduces the cycle time. Below is a benchmark of the difference in execution times. (Non-coarse clocks are also included just for completion) clock-gettime-realtime: syscall: 172 nsec/call clock-gettime-realtime: libc: 28 nsec/call clock-gettime-realtime: vdso: 22 nsec/call clock-gettime-monotonic: syscall: 171 nsec/call clock-gettime-monotonic: libc: 30 nsec/call clock-gettime-monotonic: vdso: 25 nsec/call clock-gettime-realtime-coarse: syscall: 153 nsec/call clock-gettime-realtime-coarse: libc: 16 nsec/call clock-gettime-realtime-coarse: vdso: 10 nsec/call clock-gettime-monotonic-coarse: syscall: 167 nsec/call clock-gettime-monotonic-coarse: libc: 17 nsec/call clock-gettime-monotonic-coarse: vdso: 11 nsec/call CC: Benjamin Herrenschmidt <benh@kernel.crashing.org> Signed-off-by: Santosh Sivaraj <santosh@fossix.org> --- arch/powerpc/kernel/asm-offsets.c | 2 + arch/powerpc/kernel/vdso64/gettimeofday.S | 67 ++++++++++++++++++++++++++----- 2 files changed, 58 insertions(+), 11 deletions(-) diff --git a/arch/powerpc/kernel/asm-offsets.c b/arch/powerpc/kernel/asm-offsets.c index 8cfb20e38cfe..b55c68c54dc1 100644 --- a/arch/powerpc/kernel/asm-offsets.c +++ b/arch/powerpc/kernel/asm-offsets.c @@ -396,6 +396,8 @@ int main(void) /* Other bits used by the vdso */ DEFINE(CLOCK_REALTIME, CLOCK_REALTIME); DEFINE(CLOCK_MONOTONIC, CLOCK_MONOTONIC); + DEFINE(CLOCK_REALTIME_COARSE, CLOCK_REALTIME_COARSE); + DEFINE(CLOCK_MONOTONIC_COARSE, CLOCK_MONOTONIC_COARSE); DEFINE(NSEC_PER_SEC, NSEC_PER_SEC); DEFINE(CLOCK_REALTIME_RES, MONOTONIC_RES_NSEC); diff --git a/arch/powerpc/kernel/vdso64/gettimeofday.S b/arch/powerpc/kernel/vdso64/gettimeofday.S index 382021324883..729dded195ce 100644 --- a/arch/powerpc/kernel/vdso64/gettimeofday.S +++ b/arch/powerpc/kernel/vdso64/gettimeofday.S @@ -64,6 +64,12 @@ V_FUNCTION_BEGIN(__kernel_clock_gettime) cmpwi cr0,r3,CLOCK_REALTIME cmpwi cr1,r3,CLOCK_MONOTONIC cror cr0*4+eq,cr0*4+eq,cr1*4+eq + + cmpwi cr5,r3,CLOCK_REALTIME_COARSE + cmpwi cr6,r3,CLOCK_MONOTONIC_COARSE + cror cr5*4+eq,cr5*4+eq,cr6*4+eq + + cror cr0*4+eq,cr0*4+eq,cr5*4+eq bne cr0,99f mflr r12 /* r12 saves lr */ @@ -72,6 +78,7 @@ V_FUNCTION_BEGIN(__kernel_clock_gettime) bl V_LOCAL_FUNC(__get_datapage) /* get data page */ lis r7,NSEC_PER_SEC@h /* want nanoseconds */ ori r7,r7,NSEC_PER_SEC@l + beq cr5,70f 50: bl V_LOCAL_FUNC(__do_get_tspec) /* get time from tb & kernel */ bne cr1,80f /* if not monotonic, all done */ @@ -97,19 +104,57 @@ V_FUNCTION_BEGIN(__kernel_clock_gettime) ld r0,CFG_TB_UPDATE_COUNT(r3) cmpld cr0,r0,r8 /* check if updated */ bne- 50b + b 78f - /* Add wall->monotonic offset and check for overflow or underflow. + /* + * For coarse clocks we get data directly from the vdso data page, so + * we don't need to call __do_get_tspec, but we still need to do the + * counter trick. */ - add r4,r4,r6 - add r5,r5,r9 - cmpd cr0,r5,r7 - cmpdi cr1,r5,0 - blt 1f - subf r5,r7,r5 - addi r4,r4,1 -1: bge cr1,80f - addi r4,r4,-1 - add r5,r5,r7 +70: ld r8,CFG_TB_UPDATE_COUNT(r3) + andi. r0,r8,1 /* pending update ? loop */ + bne- 70b + xor r0,r8,r8 /* create dependency */ + add r3,r3,r0 + + /* + * CLOCK_REALTIME_COARSE, below values are needed for MONOTONIC_COARSE + * too + */ + ld r4,STAMP_XTIME+TSPC64_TV_SEC(r3) + ld r5,STAMP_XTIME+TSPC64_TV_NSEC(r3) + bne cr6,75f + + /* CLOCK_MONOTONIC_COARSE */ + lwa r6,WTOM_CLOCK_SEC(r3) + lwa r9,WTOM_CLOCK_NSEC(r3) + + /* check if counter has updated */ +75: or r0,r6,r9 + or r0,r4,r5 + xor r0,r0,r0 + add r3,r3,r0 + ld r0,CFG_TB_UPDATE_COUNT(r3) + cmpld cr0,r0,r8 /* check if updated */ + bne- 70b + + /* Counter has not updated, so continue calculating proper values for + * sec and nsec if monotonic coarse, or just return with the proper + * values for realtime. + */ + bne cr6,80f + + /* Add wall->monotonic offset and check for overflow or underflow */ +78: add r4,r4,r6 + add r5,r5,r9 + cmpd cr0,r5,r7 + cmpdi cr1,r5,0 + blt 79f + subf r5,r7,r5 + addi r4,r4,1 +79: bge cr1,80f + addi r4,r4,-1 + add r5,r5,r7 80: std r4,TSPC64_TV_SEC(r11) std r5,TSPC64_TV_NSEC(r11) -- 2.13.6 ^ permalink raw reply related [flat|nested] 15+ messages in thread
* Re: [PATCH v4] powerpc/vdso64: Add support for CLOCK_{REALTIME/MONOTONIC}_COARSE 2017-10-09 8:09 ` [PATCH v4] " Santosh Sivaraj @ 2017-10-09 10:39 ` Naveen N. Rao 2017-10-10 9:03 ` Santosh Sivaraj 0 siblings, 1 reply; 15+ messages in thread From: Naveen N. Rao @ 2017-10-09 10:39 UTC (permalink / raw) To: Santosh Sivaraj Cc: linuxppc-dev, Michael Ellerman, John Stultz, Thomas Gleixner, Frederic Weisbecker, Srikar Dronamraju, Benjamin Herrenschmidt On 2017/10/09 08:09AM, Santosh Sivaraj wrote: > Current vDSO64 implementation does not have support for coarse clocks > (CLOCK_MONOTONIC_COARSE, CLOCK_REALTIME_COARSE), for which it falls back > to system call, increasing the response time, vDSO implementation reduces > the cycle time. Below is a benchmark of the difference in execution times. > > (Non-coarse clocks are also included just for completion) > > clock-gettime-realtime: syscall: 172 nsec/call > clock-gettime-realtime: libc: 28 nsec/call > clock-gettime-realtime: vdso: 22 nsec/call > clock-gettime-monotonic: syscall: 171 nsec/call > clock-gettime-monotonic: libc: 30 nsec/call > clock-gettime-monotonic: vdso: 25 nsec/call > clock-gettime-realtime-coarse: syscall: 153 nsec/call > clock-gettime-realtime-coarse: libc: 16 nsec/call > clock-gettime-realtime-coarse: vdso: 10 nsec/call > clock-gettime-monotonic-coarse: syscall: 167 nsec/call > clock-gettime-monotonic-coarse: libc: 17 nsec/call > clock-gettime-monotonic-coarse: vdso: 11 nsec/call > > CC: Benjamin Herrenschmidt <benh@kernel.crashing.org> > Signed-off-by: Santosh Sivaraj <santosh@fossix.org> > --- > arch/powerpc/kernel/asm-offsets.c | 2 + > arch/powerpc/kernel/vdso64/gettimeofday.S | 67 ++++++++++++++++++++++++++----- > 2 files changed, 58 insertions(+), 11 deletions(-) > > diff --git a/arch/powerpc/kernel/asm-offsets.c b/arch/powerpc/kernel/asm-offsets.c > index 8cfb20e38cfe..b55c68c54dc1 100644 > --- a/arch/powerpc/kernel/asm-offsets.c > +++ b/arch/powerpc/kernel/asm-offsets.c > @@ -396,6 +396,8 @@ int main(void) > /* Other bits used by the vdso */ > DEFINE(CLOCK_REALTIME, CLOCK_REALTIME); > DEFINE(CLOCK_MONOTONIC, CLOCK_MONOTONIC); > + DEFINE(CLOCK_REALTIME_COARSE, CLOCK_REALTIME_COARSE); > + DEFINE(CLOCK_MONOTONIC_COARSE, CLOCK_MONOTONIC_COARSE); > DEFINE(NSEC_PER_SEC, NSEC_PER_SEC); > DEFINE(CLOCK_REALTIME_RES, MONOTONIC_RES_NSEC); > > diff --git a/arch/powerpc/kernel/vdso64/gettimeofday.S b/arch/powerpc/kernel/vdso64/gettimeofday.S > index 382021324883..729dded195ce 100644 > --- a/arch/powerpc/kernel/vdso64/gettimeofday.S > +++ b/arch/powerpc/kernel/vdso64/gettimeofday.S > @@ -64,6 +64,12 @@ V_FUNCTION_BEGIN(__kernel_clock_gettime) > cmpwi cr0,r3,CLOCK_REALTIME > cmpwi cr1,r3,CLOCK_MONOTONIC > cror cr0*4+eq,cr0*4+eq,cr1*4+eq > + > + cmpwi cr5,r3,CLOCK_REALTIME_COARSE > + cmpwi cr6,r3,CLOCK_MONOTONIC_COARSE > + cror cr5*4+eq,cr5*4+eq,cr6*4+eq > + > + cror cr0*4+eq,cr0*4+eq,cr5*4+eq > bne cr0,99f > > mflr r12 /* r12 saves lr */ > @@ -72,6 +78,7 @@ V_FUNCTION_BEGIN(__kernel_clock_gettime) > bl V_LOCAL_FUNC(__get_datapage) /* get data page */ > lis r7,NSEC_PER_SEC@h /* want nanoseconds */ > ori r7,r7,NSEC_PER_SEC@l > + beq cr5,70f > 50: bl V_LOCAL_FUNC(__do_get_tspec) /* get time from tb & kernel */ > bne cr1,80f /* if not monotonic, all done */ > > @@ -97,19 +104,57 @@ V_FUNCTION_BEGIN(__kernel_clock_gettime) > ld r0,CFG_TB_UPDATE_COUNT(r3) > cmpld cr0,r0,r8 /* check if updated */ > bne- 50b > + b 78f > > - /* Add wall->monotonic offset and check for overflow or underflow. > + /* > + * For coarse clocks we get data directly from the vdso data page, so > + * we don't need to call __do_get_tspec, but we still need to do the > + * counter trick. > */ > - add r4,r4,r6 > - add r5,r5,r9 > - cmpd cr0,r5,r7 > - cmpdi cr1,r5,0 > - blt 1f > - subf r5,r7,r5 > - addi r4,r4,1 > -1: bge cr1,80f > - addi r4,r4,-1 > - add r5,r5,r7 > +70: ld r8,CFG_TB_UPDATE_COUNT(r3) > + andi. r0,r8,1 /* pending update ? loop */ > + bne- 70b > + xor r0,r8,r8 /* create dependency */ > + add r3,r3,r0 > + > + /* > + * CLOCK_REALTIME_COARSE, below values are needed for MONOTONIC_COARSE > + * too > + */ > + ld r4,STAMP_XTIME+TSPC64_TV_SEC(r3) > + ld r5,STAMP_XTIME+TSPC64_TV_NSEC(r3) > + bne cr6,75f > + > + /* CLOCK_MONOTONIC_COARSE */ > + lwa r6,WTOM_CLOCK_SEC(r3) > + lwa r9,WTOM_CLOCK_NSEC(r3) > + > + /* check if counter has updated */ > +75: or r0,r6,r9 > + or r0,r4,r5 > + xor r0,r0,r0 The label '75:' should be on the second instruction since we don't need to worry about r6/r9 for REALTIME_COARSE. Also, the above hunk should actually be: or r0,r6,r9 or r0,r0,r4 or r0,r0,r5 xor r0,r0,r0 Otherwise, the first 'or' will be skipped. I realized this after I replied to your previous version, but missed letting you know... > + add r3,r3,r0 > + ld r0,CFG_TB_UPDATE_COUNT(r3) > + cmpld cr0,r0,r8 /* check if updated */ > + bne- 70b I also notice that the code for dealing with CLOCK_MONOTONIC is similar for _COARSE and regular clocks. If possible, we should reuse that as well. - Naveen ^ permalink raw reply [flat|nested] 15+ messages in thread
* Re: [PATCH v4] powerpc/vdso64: Add support for CLOCK_{REALTIME/MONOTONIC}_COARSE 2017-10-09 10:39 ` Naveen N. Rao @ 2017-10-10 9:03 ` Santosh Sivaraj 2017-10-10 9:30 ` Naveen N. Rao 0 siblings, 1 reply; 15+ messages in thread From: Santosh Sivaraj @ 2017-10-10 9:03 UTC (permalink / raw) To: Naveen N. Rao; +Cc: linuxppc-dev, Michael Ellerman, Srikar Dronamraju * Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> wrote (on 2017-10-09 10:39:18 +0000): > On 2017/10/09 08:09AM, Santosh Sivaraj wrote: > > Current vDSO64 implementation does not have support for coarse clocks > > (CLOCK_MONOTONIC_COARSE, CLOCK_REALTIME_COARSE), for which it falls back > > to system call, increasing the response time, vDSO implementation reduces > > the cycle time. Below is a benchmark of the difference in execution times. > > > > (Non-coarse clocks are also included just for completion) > > > > clock-gettime-realtime: syscall: 172 nsec/call > > clock-gettime-realtime: libc: 28 nsec/call > > clock-gettime-realtime: vdso: 22 nsec/call > > clock-gettime-monotonic: syscall: 171 nsec/call > > clock-gettime-monotonic: libc: 30 nsec/call > > clock-gettime-monotonic: vdso: 25 nsec/call > > clock-gettime-realtime-coarse: syscall: 153 nsec/call > > clock-gettime-realtime-coarse: libc: 16 nsec/call > > clock-gettime-realtime-coarse: vdso: 10 nsec/call > > clock-gettime-monotonic-coarse: syscall: 167 nsec/call > > clock-gettime-monotonic-coarse: libc: 17 nsec/call > > clock-gettime-monotonic-coarse: vdso: 11 nsec/call > > > > CC: Benjamin Herrenschmidt <benh@kernel.crashing.org> > > Signed-off-by: Santosh Sivaraj <santosh@fossix.org> > > --- > > arch/powerpc/kernel/asm-offsets.c | 2 + > > arch/powerpc/kernel/vdso64/gettimeofday.S | 67 ++++++++++++++++++++++++++----- > > 2 files changed, 58 insertions(+), 11 deletions(-) > > > > diff --git a/arch/powerpc/kernel/asm-offsets.c b/arch/powerpc/kernel/asm-offsets.c > > index 8cfb20e38cfe..b55c68c54dc1 100644 > > --- a/arch/powerpc/kernel/asm-offsets.c > > +++ b/arch/powerpc/kernel/asm-offsets.c > > @@ -396,6 +396,8 @@ int main(void) > > /* Other bits used by the vdso */ > > DEFINE(CLOCK_REALTIME, CLOCK_REALTIME); > > DEFINE(CLOCK_MONOTONIC, CLOCK_MONOTONIC); > > + DEFINE(CLOCK_REALTIME_COARSE, CLOCK_REALTIME_COARSE); > > + DEFINE(CLOCK_MONOTONIC_COARSE, CLOCK_MONOTONIC_COARSE); > > DEFINE(NSEC_PER_SEC, NSEC_PER_SEC); > > DEFINE(CLOCK_REALTIME_RES, MONOTONIC_RES_NSEC); > > > > diff --git a/arch/powerpc/kernel/vdso64/gettimeofday.S b/arch/powerpc/kernel/vdso64/gettimeofday.S > > index 382021324883..729dded195ce 100644 > > --- a/arch/powerpc/kernel/vdso64/gettimeofday.S > > +++ b/arch/powerpc/kernel/vdso64/gettimeofday.S > > @@ -64,6 +64,12 @@ V_FUNCTION_BEGIN(__kernel_clock_gettime) > > cmpwi cr0,r3,CLOCK_REALTIME > > cmpwi cr1,r3,CLOCK_MONOTONIC > > cror cr0*4+eq,cr0*4+eq,cr1*4+eq > > + > > + cmpwi cr5,r3,CLOCK_REALTIME_COARSE > > + cmpwi cr6,r3,CLOCK_MONOTONIC_COARSE > > + cror cr5*4+eq,cr5*4+eq,cr6*4+eq > > + > > + cror cr0*4+eq,cr0*4+eq,cr5*4+eq > > bne cr0,99f > > > > mflr r12 /* r12 saves lr */ > > @@ -72,6 +78,7 @@ V_FUNCTION_BEGIN(__kernel_clock_gettime) > > bl V_LOCAL_FUNC(__get_datapage) /* get data page */ > > lis r7,NSEC_PER_SEC@h /* want nanoseconds */ > > ori r7,r7,NSEC_PER_SEC@l > > + beq cr5,70f > > 50: bl V_LOCAL_FUNC(__do_get_tspec) /* get time from tb & kernel */ > > bne cr1,80f /* if not monotonic, all done */ > > > > @@ -97,19 +104,57 @@ V_FUNCTION_BEGIN(__kernel_clock_gettime) > > ld r0,CFG_TB_UPDATE_COUNT(r3) > > cmpld cr0,r0,r8 /* check if updated */ > > bne- 50b > > + b 78f > > > > - /* Add wall->monotonic offset and check for overflow or underflow. > > + /* > > + * For coarse clocks we get data directly from the vdso data page, so > > + * we don't need to call __do_get_tspec, but we still need to do the > > + * counter trick. > > */ > > - add r4,r4,r6 > > - add r5,r5,r9 > > - cmpd cr0,r5,r7 > > - cmpdi cr1,r5,0 > > - blt 1f > > - subf r5,r7,r5 > > - addi r4,r4,1 > > -1: bge cr1,80f > > - addi r4,r4,-1 > > - add r5,r5,r7 > > +70: ld r8,CFG_TB_UPDATE_COUNT(r3) > > + andi. r0,r8,1 /* pending update ? loop */ > > + bne- 70b > > + xor r0,r8,r8 /* create dependency */ > > + add r3,r3,r0 > > + > > + /* > > + * CLOCK_REALTIME_COARSE, below values are needed for MONOTONIC_COARSE > > + * too > > + */ > > + ld r4,STAMP_XTIME+TSPC64_TV_SEC(r3) > > + ld r5,STAMP_XTIME+TSPC64_TV_NSEC(r3) > > + bne cr6,75f > > + > > + /* CLOCK_MONOTONIC_COARSE */ > > + lwa r6,WTOM_CLOCK_SEC(r3) > > + lwa r9,WTOM_CLOCK_NSEC(r3) > > + > > + /* check if counter has updated */ > > +75: or r0,r6,r9 > > + or r0,r4,r5 > > + xor r0,r0,r0 > > The label '75:' should be on the second instruction since we don't need > to worry about r6/r9 for REALTIME_COARSE. > > Also, the above hunk should actually be: > > or r0,r6,r9 > or r0,r0,r4 > or r0,r0,r5 > xor r0,r0,r0 > > Otherwise, the first 'or' will be skipped. I realized this after I > replied to your previous version, but missed letting you know... Yeah, I too missed it. > > > + add r3,r3,r0 > > + ld r0,CFG_TB_UPDATE_COUNT(r3) > > + cmpld cr0,r0,r8 /* check if updated */ > > + bne- 70b > > I also notice that the code for dealing with CLOCK_MONOTONIC is similar > for _COARSE and regular clocks. If possible, we should reuse that as > well. > In this case we will be adding more checks and branches in order to reuse the code. If we want to keep the code common we will have to do a lot of jumping around, code will contain a bunch of branches, which I feel will make the code/flow hard to understand. (Q: Does lot of branches have bad effect on branch prediction?) Will wait for your thoughts, before respinning. Thanks, Santosh > > - Naveen > -- ^ permalink raw reply [flat|nested] 15+ messages in thread
* Re: [PATCH v4] powerpc/vdso64: Add support for CLOCK_{REALTIME/MONOTONIC}_COARSE 2017-10-10 9:03 ` Santosh Sivaraj @ 2017-10-10 9:30 ` Naveen N. Rao 2017-10-10 23:10 ` [PATCH v6] " Santosh Sivaraj 0 siblings, 1 reply; 15+ messages in thread From: Naveen N. Rao @ 2017-10-10 9:30 UTC (permalink / raw) To: Santosh Sivaraj; +Cc: linuxppc-dev, Michael Ellerman, Srikar Dronamraju On 2017/10/10 09:03AM, Santosh Sivaraj wrote: > * Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> wrote (on 2017-10-09 10:39:18 +0000): > > > On 2017/10/09 08:09AM, Santosh Sivaraj wrote: [snip] > > > + add r3,r3,r0 > > > + ld r0,CFG_TB_UPDATE_COUNT(r3) > > > + cmpld cr0,r0,r8 /* check if updated */ > > > + bne- 70b > > > > I also notice that the code for dealing with CLOCK_MONOTONIC is similar > > for _COARSE and regular clocks. If possible, we should reuse that as > > well. > > > In this case we will be adding more checks and branches in order to reuse > the code. If we want to keep the code common we will have to do a lot of > jumping around, code will contain a bunch of branches, which I feel will make > the code/flow hard to understand. (Q: Does lot of branches have bad effect on > branch prediction?) Right - like we discussed offline, if it hurts readability, that's a good enough reason not to do this. We are only talking about a few instructions here anyway, so no need to worry too much. - Naveen ^ permalink raw reply [flat|nested] 15+ messages in thread
* [PATCH v6] powerpc/vdso64: Add support for CLOCK_{REALTIME/MONOTONIC}_COARSE 2017-10-10 9:30 ` Naveen N. Rao @ 2017-10-10 23:10 ` Santosh Sivaraj 2017-10-11 7:04 ` Naveen N. Rao 0 siblings, 1 reply; 15+ messages in thread From: Santosh Sivaraj @ 2017-10-10 23:10 UTC (permalink / raw) To: linuxppc-dev Cc: Michael Ellerman, John Stultz, Thomas Gleixner, Frederic Weisbecker, Naveen N. Rao, Srikar Dronamraju, Benjamin Herrenschmidt Current vDSO64 implementation does not have support for coarse clocks (CLOCK_MONOTONIC_COARSE, CLOCK_REALTIME_COARSE), for which it falls back to system call, increasing the response time, vDSO implementation reduces the cycle time. Below is a benchmark of the difference in execution times. (Non-coarse clocks are also included just for completion) clock-gettime-realtime: syscall: 172 nsec/call clock-gettime-realtime: libc: 28 nsec/call clock-gettime-realtime: vdso: 22 nsec/call clock-gettime-monotonic: syscall: 171 nsec/call clock-gettime-monotonic: libc: 30 nsec/call clock-gettime-monotonic: vdso: 25 nsec/call clock-gettime-realtime-coarse: syscall: 153 nsec/call clock-gettime-realtime-coarse: libc: 16 nsec/call clock-gettime-realtime-coarse: vdso: 10 nsec/call clock-gettime-monotonic-coarse: syscall: 167 nsec/call clock-gettime-monotonic-coarse: libc: 17 nsec/call clock-gettime-monotonic-coarse: vdso: 11 nsec/call CC: Benjamin Herrenschmidt <benh@kernel.crashing.org> Signed-off-by: Santosh Sivaraj <santosh@fossix.org> --- arch/powerpc/kernel/asm-offsets.c | 2 + arch/powerpc/kernel/vdso64/gettimeofday.S | 67 ++++++++++++++++++++++++++----- 2 files changed, 58 insertions(+), 11 deletions(-) diff --git a/arch/powerpc/kernel/asm-offsets.c b/arch/powerpc/kernel/asm-offsets.c index 8cfb20e38cfe..b55c68c54dc1 100644 --- a/arch/powerpc/kernel/asm-offsets.c +++ b/arch/powerpc/kernel/asm-offsets.c @@ -396,6 +396,8 @@ int main(void) /* Other bits used by the vdso */ DEFINE(CLOCK_REALTIME, CLOCK_REALTIME); DEFINE(CLOCK_MONOTONIC, CLOCK_MONOTONIC); + DEFINE(CLOCK_REALTIME_COARSE, CLOCK_REALTIME_COARSE); + DEFINE(CLOCK_MONOTONIC_COARSE, CLOCK_MONOTONIC_COARSE); DEFINE(NSEC_PER_SEC, NSEC_PER_SEC); DEFINE(CLOCK_REALTIME_RES, MONOTONIC_RES_NSEC); diff --git a/arch/powerpc/kernel/vdso64/gettimeofday.S b/arch/powerpc/kernel/vdso64/gettimeofday.S index 382021324883..b594f5c745fa 100644 --- a/arch/powerpc/kernel/vdso64/gettimeofday.S +++ b/arch/powerpc/kernel/vdso64/gettimeofday.S @@ -64,6 +64,12 @@ V_FUNCTION_BEGIN(__kernel_clock_gettime) cmpwi cr0,r3,CLOCK_REALTIME cmpwi cr1,r3,CLOCK_MONOTONIC cror cr0*4+eq,cr0*4+eq,cr1*4+eq + + cmpwi cr5,r3,CLOCK_REALTIME_COARSE + cmpwi cr6,r3,CLOCK_MONOTONIC_COARSE + cror cr5*4+eq,cr5*4+eq,cr6*4+eq + + cror cr0*4+eq,cr0*4+eq,cr5*4+eq bne cr0,99f mflr r12 /* r12 saves lr */ @@ -72,6 +78,7 @@ V_FUNCTION_BEGIN(__kernel_clock_gettime) bl V_LOCAL_FUNC(__get_datapage) /* get data page */ lis r7,NSEC_PER_SEC@h /* want nanoseconds */ ori r7,r7,NSEC_PER_SEC@l + beq cr5,70f 50: bl V_LOCAL_FUNC(__do_get_tspec) /* get time from tb & kernel */ bne cr1,80f /* if not monotonic, all done */ @@ -97,19 +104,57 @@ V_FUNCTION_BEGIN(__kernel_clock_gettime) ld r0,CFG_TB_UPDATE_COUNT(r3) cmpld cr0,r0,r8 /* check if updated */ bne- 50b + b 78f - /* Add wall->monotonic offset and check for overflow or underflow. + /* + * For coarse clocks we get data directly from the vdso data page, so + * we don't need to call __do_get_tspec, but we still need to do the + * counter trick. */ - add r4,r4,r6 - add r5,r5,r9 - cmpd cr0,r5,r7 - cmpdi cr1,r5,0 - blt 1f - subf r5,r7,r5 - addi r4,r4,1 -1: bge cr1,80f - addi r4,r4,-1 - add r5,r5,r7 +70: ld r8,CFG_TB_UPDATE_COUNT(r3) + andi. r0,r8,1 /* pending update ? loop */ + bne- 70b + xor r0,r8,r8 /* create dependency */ + add r3,r3,r0 + + /* + * CLOCK_REALTIME_COARSE, below values are needed for MONOTONIC_COARSE + * too + */ + ld r4,STAMP_XTIME+TSPC64_TV_SEC(r3) + ld r5,STAMP_XTIME+TSPC64_TV_NSEC(r3) + bne cr6,75f + + /* CLOCK_MONOTONIC_COARSE */ + lwa r6,WTOM_CLOCK_SEC(r3) + lwa r9,WTOM_CLOCK_NSEC(r3) + + /* check if counter has updated */ + or r0,r6,r9 +75: or r0,r4,r5 + xor r0,r0,r0 + add r3,r3,r0 + ld r0,CFG_TB_UPDATE_COUNT(r3) + cmpld cr0,r0,r8 /* check if updated */ + bne- 70b + + /* Counter has not updated, so continue calculating proper values for + * sec and nsec if monotonic coarse, or just return with the proper + * values for realtime. + */ + bne cr6,80f + + /* Add wall->monotonic offset and check for overflow or underflow */ +78: add r4,r4,r6 + add r5,r5,r9 + cmpd cr0,r5,r7 + cmpdi cr1,r5,0 + blt 79f + subf r5,r7,r5 + addi r4,r4,1 +79: bge cr1,80f + addi r4,r4,-1 + add r5,r5,r7 80: std r4,TSPC64_TV_SEC(r11) std r5,TSPC64_TV_NSEC(r11) -- 2.13.6 ^ permalink raw reply related [flat|nested] 15+ messages in thread
* Re: [PATCH v6] powerpc/vdso64: Add support for CLOCK_{REALTIME/MONOTONIC}_COARSE 2017-10-10 23:10 ` [PATCH v6] " Santosh Sivaraj @ 2017-10-11 7:04 ` Naveen N. Rao 2017-10-11 7:38 ` Santosh Sivaraj 0 siblings, 1 reply; 15+ messages in thread From: Naveen N. Rao @ 2017-10-11 7:04 UTC (permalink / raw) To: Santosh Sivaraj Cc: linuxppc-dev, Michael Ellerman, John Stultz, Thomas Gleixner, Frederic Weisbecker, Srikar Dronamraju, Benjamin Herrenschmidt Hi Santosh, This seems to have gone from v4 to v6 -- did I miss v5? On 2017/10/10 11:10PM, Santosh Sivaraj wrote: > Current vDSO64 implementation does not have support for coarse clocks > (CLOCK_MONOTONIC_COARSE, CLOCK_REALTIME_COARSE), for which it falls back > to system call, increasing the response time, vDSO implementation reduces > the cycle time. Below is a benchmark of the difference in execution times. > > (Non-coarse clocks are also included just for completion) > > clock-gettime-realtime: syscall: 172 nsec/call > clock-gettime-realtime: libc: 28 nsec/call > clock-gettime-realtime: vdso: 22 nsec/call > clock-gettime-monotonic: syscall: 171 nsec/call > clock-gettime-monotonic: libc: 30 nsec/call > clock-gettime-monotonic: vdso: 25 nsec/call > clock-gettime-realtime-coarse: syscall: 153 nsec/call > clock-gettime-realtime-coarse: libc: 16 nsec/call > clock-gettime-realtime-coarse: vdso: 10 nsec/call > clock-gettime-monotonic-coarse: syscall: 167 nsec/call > clock-gettime-monotonic-coarse: libc: 17 nsec/call > clock-gettime-monotonic-coarse: vdso: 11 nsec/call > > CC: Benjamin Herrenschmidt <benh@kernel.crashing.org> > Signed-off-by: Santosh Sivaraj <santosh@fossix.org> > --- > arch/powerpc/kernel/asm-offsets.c | 2 + > arch/powerpc/kernel/vdso64/gettimeofday.S | 67 ++++++++++++++++++++++++++----- > 2 files changed, 58 insertions(+), 11 deletions(-) ... and no changes since the last rev? It is better to post new versions in a separate thread and to include the changelog for easier review. - Naveen ^ permalink raw reply [flat|nested] 15+ messages in thread
* Re: [PATCH v6] powerpc/vdso64: Add support for CLOCK_{REALTIME/MONOTONIC}_COARSE 2017-10-11 7:04 ` Naveen N. Rao @ 2017-10-11 7:38 ` Santosh Sivaraj 0 siblings, 0 replies; 15+ messages in thread From: Santosh Sivaraj @ 2017-10-11 7:38 UTC (permalink / raw) To: Naveen N. Rao; +Cc: linuxppc-dev * Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> wrote (on 2017-10-11 07:04:43 +0000): > Hi Santosh, > This seems to have gone from v4 to v6 -- did I miss v5? Nope, this is indeed v5, a typo :-( > > On 2017/10/10 11:10PM, Santosh Sivaraj wrote: > > Current vDSO64 implementation does not have support for coarse clocks > > (CLOCK_MONOTONIC_COARSE, CLOCK_REALTIME_COARSE), for which it falls back > > to system call, increasing the response time, vDSO implementation reduces > > the cycle time. Below is a benchmark of the difference in execution times. > > > > (Non-coarse clocks are also included just for completion) > > > > clock-gettime-realtime: syscall: 172 nsec/call > > clock-gettime-realtime: libc: 28 nsec/call > > clock-gettime-realtime: vdso: 22 nsec/call > > clock-gettime-monotonic: syscall: 171 nsec/call > > clock-gettime-monotonic: libc: 30 nsec/call > > clock-gettime-monotonic: vdso: 25 nsec/call > > clock-gettime-realtime-coarse: syscall: 153 nsec/call > > clock-gettime-realtime-coarse: libc: 16 nsec/call > > clock-gettime-realtime-coarse: vdso: 10 nsec/call > > clock-gettime-monotonic-coarse: syscall: 167 nsec/call > > clock-gettime-monotonic-coarse: libc: 17 nsec/call > > clock-gettime-monotonic-coarse: vdso: 11 nsec/call > > > > CC: Benjamin Herrenschmidt <benh@kernel.crashing.org> > > Signed-off-by: Santosh Sivaraj <santosh@fossix.org> > > --- > > arch/powerpc/kernel/asm-offsets.c | 2 + > > arch/powerpc/kernel/vdso64/gettimeofday.S | 67 ++++++++++++++++++++++++++----- > > 2 files changed, 58 insertions(+), 11 deletions(-) > > ... and no changes since the last rev? There is that one line change of label. But otherwise its the same. > > It is better to post new versions in a separate thread and to include > the changelog for easier review. > Sure. Thanks, Santosh > > - Naveen > -- ^ permalink raw reply [flat|nested] 15+ messages in thread
* Re: [PATCH 1/2] powerpc/vdso64: Coarse timer support preparatory patch 2017-09-18 9:23 [PATCH 1/2] powerpc/vdso64: Coarse timer support preparatory patch Santosh Sivaraj 2017-09-18 9:23 ` [PATCH 2/2] powerpc/vdso64: Add support for CLOCK_{REALTIME/MONOTONIC}_COARSE Santosh Sivaraj @ 2017-10-06 9:03 ` Naveen N. Rao 2017-10-06 10:13 ` Michael Ellerman 1 sibling, 1 reply; 15+ messages in thread From: Naveen N. Rao @ 2017-10-06 9:03 UTC (permalink / raw) To: Santosh Sivaraj Cc: linuxppc-dev, Michael Ellerman, John Stultz, Thomas Gleixner, Frederic Weisbecker, Srikar Dronamraju Hi Santosh, On 2017/09/18 09:23AM, Santosh Sivaraj wrote: > Reorganize code to make it easy to introduce CLOCK_REALTIME_COARSE and > CLOCK_MONOTONIC_COARSE timer support. > > Signed-off-by: Santosh Sivaraj <santosh@fossix.org> > --- > arch/powerpc/kernel/vdso64/gettimeofday.S | 14 ++++++++------ > 1 file changed, 8 insertions(+), 6 deletions(-) > > diff --git a/arch/powerpc/kernel/vdso64/gettimeofday.S b/arch/powerpc/kernel/vdso64/gettimeofday.S > index 382021324883..a0b4943811db 100644 > --- a/arch/powerpc/kernel/vdso64/gettimeofday.S > +++ b/arch/powerpc/kernel/vdso64/gettimeofday.S > @@ -60,18 +60,20 @@ V_FUNCTION_END(__kernel_gettimeofday) > */ > V_FUNCTION_BEGIN(__kernel_clock_gettime) > .cfi_startproc > + mr r11,r4 /* r11 saves tp */ > + mflr r12 /* r12 saves lr */ > + lis r7,NSEC_PER_SEC@h /* want nanoseconds */ > + ori r7,r7,NSEC_PER_SEC@l > + > /* Check for supported clock IDs */ > cmpwi cr0,r3,CLOCK_REALTIME > cmpwi cr1,r3,CLOCK_MONOTONIC > cror cr0*4+eq,cr0*4+eq,cr1*4+eq > - bne cr0,99f > + beq cr0,49f > > - mflr r12 /* r12 saves lr */ > + b 99f /* Fallback to syscall */ 'beq', followed by a 'b' looks weird without considering the next patch. I think this can be organized better to not have to update r7/r11/r12 if using the system call. See next patch for my comments. > .cfi_register lr,r12 If you move the mflr, you should move the above line along with it. - Naveen > - mr r11,r4 /* r11 saves tp */ > - bl V_LOCAL_FUNC(__get_datapage) /* get data page */ > - lis r7,NSEC_PER_SEC@h /* want nanoseconds */ > - ori r7,r7,NSEC_PER_SEC@l > +49: bl V_LOCAL_FUNC(__get_datapage) /* get data page */ > 50: bl V_LOCAL_FUNC(__do_get_tspec) /* get time from tb & kernel */ > bne cr1,80f /* if not monotonic, all done */ > > -- > 2.13.5 > ^ permalink raw reply [flat|nested] 15+ messages in thread
* Re: [PATCH 1/2] powerpc/vdso64: Coarse timer support preparatory patch 2017-10-06 9:03 ` [PATCH 1/2] powerpc/vdso64: Coarse timer support preparatory patch Naveen N. Rao @ 2017-10-06 10:13 ` Michael Ellerman 0 siblings, 0 replies; 15+ messages in thread From: Michael Ellerman @ 2017-10-06 10:13 UTC (permalink / raw) To: Naveen N. Rao, Santosh Sivaraj Cc: linuxppc-dev, John Stultz, Thomas Gleixner, Frederic Weisbecker, Srikar Dronamraju Thanks for reviewing Naveen. "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com> writes: > On 2017/09/18 09:23AM, Santosh Sivaraj wrote: >> diff --git a/arch/powerpc/kernel/vdso64/gettimeofday.S b/arch/powerpc/kernel/vdso64/gettimeofday.S >> index 382021324883..a0b4943811db 100644 >> --- a/arch/powerpc/kernel/vdso64/gettimeofday.S >> +++ b/arch/powerpc/kernel/vdso64/gettimeofday.S >> @@ -60,18 +60,20 @@ V_FUNCTION_END(__kernel_gettimeofday) >> */ >> V_FUNCTION_BEGIN(__kernel_clock_gettime) >> .cfi_startproc >> + mr r11,r4 /* r11 saves tp */ >> + mflr r12 /* r12 saves lr */ >> + lis r7,NSEC_PER_SEC@h /* want nanoseconds */ >> + ori r7,r7,NSEC_PER_SEC@l >> + >> /* Check for supported clock IDs */ >> cmpwi cr0,r3,CLOCK_REALTIME >> cmpwi cr1,r3,CLOCK_MONOTONIC >> cror cr0*4+eq,cr0*4+eq,cr1*4+eq >> - bne cr0,99f >> + beq cr0,49f >> >> - mflr r12 /* r12 saves lr */ >> + b 99f /* Fallback to syscall */ > > 'beq', followed by a 'b' looks weird without considering the next patch. > I think this can be organized better to not have to update r7/r11/r12 if > using the system call. See next patch for my comments. > >> .cfi_register lr,r12 > > If you move the mflr, you should move the above line along with it. s/should/must/. It literally says "lr is saved in r12". cheers ^ permalink raw reply [flat|nested] 15+ messages in thread
end of thread, other threads:[~2017-10-11 7:38 UTC | newest]
Thread overview: 15+ messages (download: mbox.gz / follow: Atom feed)
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2017-09-18 9:23 [PATCH 1/2] powerpc/vdso64: Coarse timer support preparatory patch Santosh Sivaraj
2017-09-18 9:23 ` [PATCH 2/2] powerpc/vdso64: Add support for CLOCK_{REALTIME/MONOTONIC}_COARSE Santosh Sivaraj
2017-10-06 9:28 ` Naveen N. Rao
2017-10-09 6:27 ` Santosh Sivaraj
2017-10-06 11:25 ` Naveen N. Rao
2017-10-09 6:23 ` Santosh Sivaraj
2017-10-09 8:09 ` [PATCH v4] " Santosh Sivaraj
2017-10-09 10:39 ` Naveen N. Rao
2017-10-10 9:03 ` Santosh Sivaraj
2017-10-10 9:30 ` Naveen N. Rao
2017-10-10 23:10 ` [PATCH v6] " Santosh Sivaraj
2017-10-11 7:04 ` Naveen N. Rao
2017-10-11 7:38 ` Santosh Sivaraj
2017-10-06 9:03 ` [PATCH 1/2] powerpc/vdso64: Coarse timer support preparatory patch Naveen N. Rao
2017-10-06 10:13 ` Michael Ellerman
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