From: Paul Mackerras <paulus@samba.org>
To: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
Cc: linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH -V3 09/11] arch/powerpc: Use 50 bits of VSID in slbmte
Date: Mon, 23 Jul 2012 19:36:11 +1000 [thread overview]
Message-ID: <20120723093611.GA29264@bloggs.ozlabs.ibm.com> (raw)
In-Reply-To: <87394ij3aa.fsf@skywalker.in.ibm.com>
On Mon, Jul 23, 2012 at 01:51:49PM +0530, Aneesh Kumar K.V wrote:
> Paul Mackerras <paulus@samba.org> writes:
>
> > On Mon, Jul 09, 2012 at 06:43:39PM +0530, Aneesh Kumar K.V wrote:
> >> From: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
> >>
> >> Increase the number of valid VSID bits in slbmte instruction.
> >> We will use the new bits when we increase valid VSID bits.
> >>
> >> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
> >> ---
> >> arch/powerpc/mm/slb_low.S | 4 ++--
> >> 1 file changed, 2 insertions(+), 2 deletions(-)
> >>
> >> diff --git a/arch/powerpc/mm/slb_low.S b/arch/powerpc/mm/slb_low.S
> >> index c355af6..c1fc81c 100644
> >> --- a/arch/powerpc/mm/slb_low.S
> >> +++ b/arch/powerpc/mm/slb_low.S
> >> @@ -226,7 +226,7 @@ _GLOBAL(slb_allocate_user)
> >> */
> >> slb_finish_load:
> >> ASM_VSID_SCRAMBLE(r10,r9,256M)
> >> - rldimi r11,r10,SLB_VSID_SHIFT,16 /* combine VSID and flags */
> >> + rldimi r11,r10,SLB_VSID_SHIFT,2 /* combine VSID and flags */
> >
> > You can't do that without either changing ASM_VSID_SCRAMBLE or masking
> > the VSID it generates to 36 bits, since the logic in ASM_VSID_SCRAMBLE
> > can leave non-zero bits in the high 28 bits of the result. Similarly
> > for the 1T case.
> >
>
> How about change ASM_VSID_SCRAMBLE to clear the high bits ? That would
> also make it close to vsid_scramble()
One more instruction in a hot path - I'd rather not. How about
changing the rldimi instruction to:
rldimi r11,r10,SLB_VSID_SHIFT,(64-SLB_VSID_SHIFT-VSID_BITS_256M)
and similarly for the 1T case. That will give the proper masking
when you change VSID_BITS_256M.
Paul.
next prev parent reply other threads:[~2012-07-23 9:36 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-07-09 13:13 [PATCH -V3 0/11] arch/powerpc: Add 64TB support to ppc64 Aneesh Kumar K.V
2012-07-09 13:13 ` [PATCH -V3 01/11] arch/powerpc: Use hpt_va to compute virtual address Aneesh Kumar K.V
2012-07-22 23:17 ` Paul Mackerras
2012-07-09 13:13 ` [PATCH -V3 02/11] arch/powerpc: Simplify hpte_decode Aneesh Kumar K.V
2012-07-22 23:26 ` Paul Mackerras
2012-07-23 5:41 ` Aneesh Kumar K.V
2012-07-09 13:13 ` [PATCH -V3 03/11] arch/powerpc: Convert virtual address to vpn Aneesh Kumar K.V
2012-07-09 22:41 ` Stephen Rothwell
2012-07-10 6:12 ` Aneesh Kumar K.V
2012-07-09 23:06 ` Stephen Rothwell
2012-07-10 6:15 ` Aneesh Kumar K.V
2012-07-22 23:42 ` Paul Mackerras
2012-07-23 5:54 ` Aneesh Kumar K.V
2012-07-09 13:13 ` [PATCH -V3 04/11] arch/powerpc: Rename va " Aneesh Kumar K.V
2012-07-22 23:46 ` Paul Mackerras
2012-07-23 6:14 ` Aneesh Kumar K.V
2012-07-09 13:13 ` [PATCH -V3 05/11] arch/powerpc: remove masking top 16 bit of va in tlb invalidate Aneesh Kumar K.V
2012-07-22 23:56 ` Paul Mackerras
2012-07-23 1:22 ` Benjamin Herrenschmidt
2012-07-23 3:49 ` Paul Mackerras
2012-07-23 6:44 ` Aneesh Kumar K.V
2012-07-23 6:48 ` Benjamin Herrenschmidt
2012-07-09 13:13 ` [PATCH -V3 06/11] arch/powerpc: Make KERN_VIRT_SIZE not dependend on PGTABLE_RANGE Aneesh Kumar K.V
2012-07-22 23:57 ` Paul Mackerras
2012-07-09 13:13 ` [PATCH -V3 07/11] arch/powerpc: Increase the slice range to 64TB Aneesh Kumar K.V
2012-07-23 0:00 ` Paul Mackerras
2012-07-23 7:13 ` Aneesh Kumar K.V
2012-07-09 13:13 ` [PATCH -V3 08/11] arch/powerpc: Make some of the PGTABLE_RANGE dependency explicit Aneesh Kumar K.V
2012-07-23 0:20 ` Paul Mackerras
2012-07-23 7:29 ` Aneesh Kumar K.V
2012-07-09 13:13 ` [PATCH -V3 09/11] arch/powerpc: Use 50 bits of VSID in slbmte Aneesh Kumar K.V
2012-07-23 0:06 ` Paul Mackerras
2012-07-23 8:21 ` Aneesh Kumar K.V
2012-07-23 9:36 ` Paul Mackerras [this message]
2012-07-23 10:22 ` Aneesh Kumar K.V
2012-07-09 13:13 ` [PATCH -V3 10/11] arch/powerpc: Use 32bit array for slb cache Aneesh Kumar K.V
2012-07-23 0:27 ` Paul Mackerras
2012-07-23 8:25 ` Aneesh Kumar K.V
2012-07-09 13:13 ` [PATCH -V3 11/11] arch/powerpc: Add 64TB support Aneesh Kumar K.V
2012-07-23 0:15 ` Paul Mackerras
2012-07-23 8:49 ` Aneesh Kumar K.V
2012-07-23 9:39 ` Paul Mackerras
2012-07-23 10:22 ` Aneesh Kumar K.V
2012-07-23 11:06 ` Paul Mackerras
2012-07-24 8:37 ` Aneesh Kumar K.V
2012-07-24 9:14 ` Aneesh Kumar K.V
2012-07-24 19:50 ` Aneesh Kumar K.V
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