* [PATCH] 2.6 timebase synchronization
@ 2003-08-08 0:15 Samuel Rydh
2003-08-09 1:13 ` Samuel Rydh
0 siblings, 1 reply; 8+ messages in thread
From: Samuel Rydh @ 2003-08-08 0:15 UTC (permalink / raw)
To: paulus; +Cc: benh, linuxppc-dev
Hi,
Here is a patch that provides improved generic SMP timebase
synchronization for 2.6.
The calibration error is typically 0 ticks (at least on my machine).
Without this patch, the difference is about 2 * 10^6 ticks...
/Samuel
# This is a BitKeeper generated patch for the following project:
# Project Name: Linux kernel tree
# This patch format is intended for GNU patch command version 2.5 or higher.
# This patch includes the following deltas:
# ChangeSet 1.998 -> 1.999
# arch/ppc/kernel/Makefile 1.51 -> 1.52
# arch/ppc/kernel/smp.c 1.35 -> 1.36
# (new) -> 1.1 arch/ppc/kernel/smp-tbsync.c
#
# The following is the BitKeeper ChangeSet Log
# --------------------------------------------
# 03/08/08 samuel@ibrium.se 1.999
# SMP timebase synchronization
# --------------------------------------------
#
diff -Nru a/arch/ppc/kernel/Makefile b/arch/ppc/kernel/Makefile
--- a/arch/ppc/kernel/Makefile Fri Aug 8 01:51:49 2003
+++ b/arch/ppc/kernel/Makefile Fri Aug 8 01:51:49 2003
@@ -25,7 +25,7 @@
obj-$(CONFIG_PCI) += pci.o
obj-$(CONFIG_PCI) += pci-dma.o
obj-$(CONFIG_KGDB) += ppc-stub.o
-obj-$(CONFIG_SMP) += smp.o
+obj-$(CONFIG_SMP) += smp.o smp-tbsync.o
obj-$(CONFIG_TAU) += temp.o
ifdef CONFIG_MATH_EMULATION
diff -Nru a/arch/ppc/kernel/smp-tbsync.c b/arch/ppc/kernel/smp-tbsync.c
--- /dev/null Wed Dec 31 16:00:00 1969
+++ b/arch/ppc/kernel/smp-tbsync.c Fri Aug 8 01:51:49 2003
@@ -0,0 +1,187 @@
+/*
+ * Smp timebase synchronization for ppc.
+ *
+ * Copyright (C) 2003 Samuel Rydh (samuel@ibrium.se)
+ *
+ */
+
+#include <linux/config.h>
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/smp.h>
+#include <linux/unistd.h>
+#include <linux/init.h>
+#include <asm/atomic.h>
+#include <asm/smp.h>
+#include <asm/time.h>
+
+#define NUM_ITER 300
+
+enum {
+ kExit=0, kSetAndTest, kTest
+};
+
+/* keep things aligned in order to avoid cache ping-pong */
+struct tbsync_vars {
+ /* CPU0 write */
+ volatile int tbu;
+ volatile int tbl;
+ volatile int mark;
+ volatile int handshake;
+ volatile int cmd;
+ int filler1[3+8];
+
+ /* CPU0 and CPU1 write */
+ atomic_t contest;
+};
+
+static volatile int tbsync_ack;
+static volatile int running;
+
+static struct tbsync_vars *tbsync;
+
+
+#define I_SYNC() asm volatile("sync; isync");
+#define CONTEST_CACHE_FLUSH() asm volatile("dcbf 0,%0 ; sync ; isync" : : \
+ "r" (&tbsync->contest) );
+
+
+static int __devinit
+enter_contest( int mark, int add )
+{
+ while( (int)(get_tbl() - mark) < 0 )
+ ;
+ return atomic_add_return( add, &tbsync->contest );
+}
+
+void __devinit
+smp_generic_take_timebase( void )
+{
+ int cmd, tbl;
+
+ while( !running )
+ ;
+ for( ;; ) {
+ tbsync_ack = 1;
+ while( !tbsync->handshake )
+ ;
+
+ I_SYNC();
+
+ cmd = tbsync->cmd;
+ tbl = tbsync->tbl;
+ tbsync_ack = 0;
+ if( cmd == kExit )
+ return;
+
+ while( tbsync->handshake )
+ ;
+ if( cmd == kSetAndTest ) {
+ asm volatile ("isync");
+ asm volatile ("mttbl %0" :: "r" (tbl) );
+ asm volatile ("mttbu %0" :: "r" (tbsync->tbu) );
+ }
+ (void) enter_contest( tbsync->mark, 2 );
+
+ CONTEST_CACHE_FLUSH();
+ }
+}
+
+static int __devinit
+start_contest( int cmd, int offset, int num )
+{
+ int i, tbu, tbl, mark, result, score=0;
+
+ tbsync->cmd = cmd;
+
+ for( i=-3; i<num; ) {
+ atomic_set( &tbsync->contest, 0 );
+ CONTEST_CACHE_FLUSH();
+
+ tbl = get_tbl() + 2000;
+ tbsync->tbu = tbu = get_tbu();
+ tbsync->tbl = tbl + offset;
+ tbsync->mark = mark = tbl + 500;
+
+ I_SYNC();
+
+ tbsync->handshake = 1;
+ while( tbsync_ack )
+ ;
+
+ while( (int)(get_tbl() - tbl) <= 0 )
+ ;
+ tbsync->handshake = 0;
+ result = enter_contest( mark, -1 );
+
+ while( !tbsync_ack )
+ ;
+
+ if( tbsync->tbu != get_tbu() || ((tbsync->tbl ^ get_tbl()) & 0x80000000) )
+ continue;
+
+ if( i++ > 0 )
+ score += result;
+ }
+ return score;
+}
+
+void __devinit
+smp_generic_give_timebase( void )
+{
+ int i, offset, score, min=0, max=5000, next_offset=1000;
+ int best=10000, best_offset;
+
+ printk("Synchronizing timebase\n");
+
+ /* if this fails then this kernel won't work anyway... */
+ tbsync = kmalloc( sizeof(*tbsync), GFP_KERNEL );
+ memset( tbsync, 0, sizeof(*tbsync) );
+ I_SYNC();
+ running = 1;
+ while( !tbsync_ack )
+ ;
+
+ /* binary search for optimal offset */
+ do {
+ offset = next_offset;
+ score = start_contest( kSetAndTest, offset, NUM_ITER );
+
+ printk("score %d, offset %d [%d..%d]\n", score, offset, min, max );
+
+ if( score > 0 )
+ max = offset;
+ else {
+ min = offset;
+ score = -score;
+ }
+ if( score < best ) {
+ best_offset = offset;
+ best = score;
+ }
+ next_offset = (min + max)/2;
+ } while( offset != next_offset );
+
+ /* guard against inaccurate mttb */
+ for( i=0; i<10; i++ ) {
+ if( (score=start_contest(kTest, best_offset, NUM_ITER)) < 0 )
+ score = -score;
+ if( score <= best || score < 20 )
+ break;
+ start_contest( kSetAndTest, best_offset, NUM_ITER/10 );
+ }
+ printk("Final timbase offset: %d (%d/%d)\n", best_offset, score, NUM_ITER );
+
+ /* exiting */
+ tbsync->cmd = kExit;
+ I_SYNC();
+ tbsync->handshake = 1;
+ while( tbsync_ack )
+ ;
+ tbsync->handshake = 0;
+ kfree( tbsync );
+ tbsync = NULL;
+
+ /* all done */
+ smp_tb_synchronized = 1;
+}
diff -Nru a/arch/ppc/kernel/smp.c b/arch/ppc/kernel/smp.c
--- a/arch/ppc/kernel/smp.c Fri Aug 8 01:51:49 2003
+++ b/arch/ppc/kernel/smp.c Fri Aug 8 01:51:49 2003
@@ -58,10 +58,6 @@
/* all cpu mappings are 1-1 -- Cort */
volatile unsigned long cpu_callin_map[NR_CPUS];
-#define TB_SYNC_PASSES 4
-volatile unsigned long __initdata tb_sync_flag = 0;
-volatile unsigned long __initdata tb_offset = 0;
-
int start_secondary(void *);
extern int cpu_idle(void *unused);
void smp_call_function_interrupt(void);
@@ -288,41 +284,6 @@
atomic_inc(&call_data->finished);
}
-/* FIXME: Do this properly for all archs --RR */
-static spinlock_t timebase_lock = SPIN_LOCK_UNLOCKED;
-static unsigned int timebase_upper = 0, timebase_lower = 0;
-
-void __devinit
-smp_generic_give_timebase(void)
-{
- spin_lock(&timebase_lock);
- do {
- timebase_upper = get_tbu();
- timebase_lower = get_tbl();
- } while (timebase_upper != get_tbu());
- spin_unlock(&timebase_lock);
-
- while (timebase_upper || timebase_lower)
- rmb();
-}
-
-void __devinit
-smp_generic_take_timebase(void)
-{
- int done = 0;
-
- while (!done) {
- spin_lock(&timebase_lock);
- if (timebase_upper || timebase_lower) {
- set_tb(timebase_upper, timebase_lower);
- timebase_upper = 0;
- timebase_lower = 0;
- done = 1;
- }
- spin_unlock(&timebase_lock);
- }
-}
-
static void __devinit smp_store_cpu_info(int id)
{
struct cpuinfo_PPC *c = &cpu_data[id];
@@ -423,7 +384,7 @@
/* wake up cpu */
smp_ops->kick_cpu(cpu);
-
+
/*
* wait to see if the cpu made a callin (is actually up).
* use this value that I found through experimentation.
** Sent via the linuxppc-dev mail list. See http://lists.linuxppc.org/
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH] 2.6 timebase synchronization
2003-08-08 0:15 [PATCH] 2.6 timebase synchronization Samuel Rydh
@ 2003-08-09 1:13 ` Samuel Rydh
2003-08-09 8:58 ` Benjamin Herrenschmidt
2003-08-10 2:09 ` Paul Mackerras
0 siblings, 2 replies; 8+ messages in thread
From: Samuel Rydh @ 2003-08-09 1:13 UTC (permalink / raw)
To: linuxppc-dev; +Cc: paulus
On Fri, Aug 08, 2003 at 02:15:23AM +0200, Samuel Rydh wrote:
>
> Hi,
>
> Here is a patch that provides improved generic SMP timebase
> synchronization for 2.6.
>
Attached is an improved version of the patch.
/Samuel
diff -Nru a/arch/ppc/kernel/Makefile b/arch/ppc/kernel/Makefile
--- a/arch/ppc/kernel/Makefile Sat Aug 9 03:10:58 2003
+++ b/arch/ppc/kernel/Makefile Sat Aug 9 03:10:58 2003
@@ -25,7 +25,7 @@
obj-$(CONFIG_PCI) += pci.o
obj-$(CONFIG_PCI) += pci-dma.o
obj-$(CONFIG_KGDB) += ppc-stub.o
-obj-$(CONFIG_SMP) += smp.o
+obj-$(CONFIG_SMP) += smp.o smp-tbsync.o
obj-$(CONFIG_TAU) += temp.o
ifdef CONFIG_MATH_EMULATION
diff -Nru a/arch/ppc/kernel/smp-tbsync.c b/arch/ppc/kernel/smp-tbsync.c
--- /dev/null Wed Dec 31 16:00:00 1969
+++ b/arch/ppc/kernel/smp-tbsync.c Sat Aug 9 03:10:58 2003
@@ -0,0 +1,181 @@
+/*
+ * Smp timebase synchronization for ppc.
+ *
+ * Copyright (C) 2003 Samuel Rydh (samuel@ibrium.se)
+ *
+ */
+
+#include <linux/config.h>
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/smp.h>
+#include <linux/unistd.h>
+#include <linux/init.h>
+#include <asm/atomic.h>
+#include <asm/smp.h>
+#include <asm/time.h>
+
+#define NUM_ITER 300
+
+enum {
+ kExit=0, kSetAndTest, kTest
+};
+
+static struct {
+ volatile int tbu;
+ volatile int tbl;
+ volatile int mark;
+ volatile int cmd;
+ volatile int handshake;
+ int filler[3];
+
+ volatile int ack;
+ int filler2[7];
+
+ volatile int race_result;
+} *tbsync;
+
+static volatile int running;
+
+static void __devinit
+enter_contest( int mark, int add )
+{
+ while( (int)(get_tbl() - mark) < 0 )
+ tbsync->race_result = add;
+}
+
+void __devinit
+smp_generic_take_timebase( void )
+{
+ int cmd, tbl, tbu;
+
+ local_irq_disable();
+ while( !running )
+ ;
+ rmb();
+
+ for( ;; ) {
+ tbsync->ack = 1;
+ while( !tbsync->handshake )
+ ;
+ rmb();
+
+ cmd = tbsync->cmd;
+ tbl = tbsync->tbl;
+ tbu = tbsync->tbu;
+ tbsync->ack = 0;
+ if( cmd == kExit )
+ return;
+
+ if( cmd == kSetAndTest ) {
+ while( tbsync->handshake )
+ ;
+ asm volatile ("mttbl %0" :: "r" (tbl) );
+ asm volatile ("mttbu %0" :: "r" (tbu) );
+ } else {
+ while( tbsync->handshake )
+ ;
+ }
+ enter_contest( tbsync->mark, -1 );
+ }
+ local_irq_enable();
+}
+
+static int __devinit
+start_contest( int cmd, int offset, int num )
+{
+ int i, tbu, tbl, mark, score=0;
+
+ tbsync->cmd = cmd;
+
+ local_irq_disable();
+ for( i=-3; i<num; ) {
+ tbl = get_tbl() + 400;
+ tbsync->tbu = tbu = get_tbu();
+ tbsync->tbl = tbl + offset;
+ tbsync->mark = mark = tbl + 400;
+
+ wmb();
+
+ tbsync->handshake = 1;
+ while( tbsync->ack )
+ ;
+
+ while( (int)(get_tbl() - tbl) <= 0 )
+ ;
+ tbsync->handshake = 0;
+ enter_contest( mark, 1 );
+
+ while( !tbsync->ack )
+ ;
+
+ if( tbsync->tbu != get_tbu() || ((tbsync->tbl ^ get_tbl()) & 0x80000000) )
+ continue;
+ if( i++ > 0 )
+ score += tbsync->race_result;
+ }
+ local_irq_enable();
+ return score;
+}
+
+void __devinit
+smp_generic_give_timebase( void )
+{
+ int i, score, score2, old, min=0, max=5000, offset=1000;
+
+ printk("Synchronizing timebase\n");
+
+ /* if this fails then this kernel won't work anyway... */
+ tbsync = kmalloc( sizeof(*tbsync), GFP_KERNEL );
+ memset( tbsync, 0, sizeof(*tbsync) );
+ mb();
+ running = 1;
+
+ while( !tbsync->ack )
+ ;
+
+ /* binary search */
+ for( old=-1 ; old != offset ; offset=(min+max)/2 ) {
+ score = start_contest( kSetAndTest, offset, NUM_ITER );
+
+ printk("score %d, offset %d\n", score, offset );
+
+ if( score > 0 )
+ max = offset;
+ else
+ min = offset;
+ old = offset;
+ }
+ score = start_contest( kSetAndTest, min, NUM_ITER );
+ score2 = start_contest( kSetAndTest, max, NUM_ITER );
+
+ printk( "Min %d (score %d), Max %d (score %d)\n", min, score, max, score2 );
+ score = abs( score );
+ score2 = abs( score2 );
+ offset = (score < score2) ? min : max;
+
+ /* guard against inaccurate mttb */
+ for( i=0; i<10; i++ ) {
+ start_contest( kSetAndTest, offset, NUM_ITER/10 );
+
+ if( (score2=start_contest(kTest, offset, NUM_ITER)) < 0 )
+ score2 = -score2;
+ if( score2 <= score || score2 < 20 )
+ break;
+ }
+ printk("Final offset: %d (%d/%d)\n", offset, score2, NUM_ITER );
+
+ /* exiting */
+ tbsync->cmd = kExit;
+ wmb();
+ tbsync->handshake = 1;
+ while( tbsync->ack )
+ ;
+ tbsync->handshake = 0;
+ kfree( tbsync );
+ tbsync = NULL;
+ running = 0;
+
+ /* all done */
+ smp_tb_synchronized = 1;
+}
diff -Nru a/arch/ppc/kernel/smp.c b/arch/ppc/kernel/smp.c
--- a/arch/ppc/kernel/smp.c Sat Aug 9 03:10:58 2003
+++ b/arch/ppc/kernel/smp.c Sat Aug 9 03:10:58 2003
@@ -58,10 +58,6 @@
/* all cpu mappings are 1-1 -- Cort */
volatile unsigned long cpu_callin_map[NR_CPUS];
-#define TB_SYNC_PASSES 4
-volatile unsigned long __initdata tb_sync_flag = 0;
-volatile unsigned long __initdata tb_offset = 0;
-
int start_secondary(void *);
extern int cpu_idle(void *unused);
void smp_call_function_interrupt(void);
@@ -288,41 +284,6 @@
atomic_inc(&call_data->finished);
}
-/* FIXME: Do this properly for all archs --RR */
-static spinlock_t timebase_lock = SPIN_LOCK_UNLOCKED;
-static unsigned int timebase_upper = 0, timebase_lower = 0;
-
-void __devinit
-smp_generic_give_timebase(void)
-{
- spin_lock(&timebase_lock);
- do {
- timebase_upper = get_tbu();
- timebase_lower = get_tbl();
- } while (timebase_upper != get_tbu());
- spin_unlock(&timebase_lock);
-
- while (timebase_upper || timebase_lower)
- rmb();
-}
-
-void __devinit
-smp_generic_take_timebase(void)
-{
- int done = 0;
-
- while (!done) {
- spin_lock(&timebase_lock);
- if (timebase_upper || timebase_lower) {
- set_tb(timebase_upper, timebase_lower);
- timebase_upper = 0;
- timebase_lower = 0;
- done = 1;
- }
- spin_unlock(&timebase_lock);
- }
-}
-
static void __devinit smp_store_cpu_info(int id)
{
struct cpuinfo_PPC *c = &cpu_data[id];
@@ -423,7 +384,7 @@
/* wake up cpu */
smp_ops->kick_cpu(cpu);
-
+
/*
* wait to see if the cpu made a callin (is actually up).
* use this value that I found through experimentation.
** Sent via the linuxppc-dev mail list. See http://lists.linuxppc.org/
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH] 2.6 timebase synchronization
2003-08-09 1:13 ` Samuel Rydh
@ 2003-08-09 8:58 ` Benjamin Herrenschmidt
2003-08-09 11:48 ` Samuel Rydh
2003-08-10 2:09 ` Paul Mackerras
1 sibling, 1 reply; 8+ messages in thread
From: Benjamin Herrenschmidt @ 2003-08-09 8:58 UTC (permalink / raw)
To: Samuel Rydh; +Cc: linuxppc-dev, Paul Mackerras
On Sat, 2003-08-09 at 03:13, Samuel Rydh wrote:
> On Fri, Aug 08, 2003 at 02:15:23AM +0200, Samuel Rydh wrote:
> >
> > Hi,
> >
> > Here is a patch that provides improved generic SMP timebase
> > synchronization for 2.6.
> >
>
> Attached is an improved version of the patch.
I'm on vacation now, I can't test it until I'm back, but that
looks quite good overall (except maybe the MacOS-like constant
naming for kXXXX :)
However, does it work with more than 2 CPUs ? It seem to be rather
dual CPU centric from my understanding of the ack mecanism... The TB sync
code is also used on 4 CPU daystar machines and possibly some other chrp
with more than 2 CPUs.
Paul, any comment ?
Ben.
** Sent via the linuxppc-dev mail list. See http://lists.linuxppc.org/
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH] 2.6 timebase synchronization
2003-08-09 8:58 ` Benjamin Herrenschmidt
@ 2003-08-09 11:48 ` Samuel Rydh
0 siblings, 0 replies; 8+ messages in thread
From: Samuel Rydh @ 2003-08-09 11:48 UTC (permalink / raw)
To: Benjamin Herrenschmidt; +Cc: linuxppc-dev, Paul Mackerras
On Sat, Aug 09, 2003 at 10:58:11AM +0200, Benjamin Herrenschmidt wrote:
> I'm on vacation now, I can't test it until I'm back, but that
> looks quite good overall (except maybe the MacOS-like constant
> naming for kXXXX :)
>
> However, does it work with more than 2 CPUs ?
Yes, it does. The code simply passes the timestamp from CPU0
to the one currently beeing booted (the CPU0 timebase is
not affected).
> It seem to be rather
> dual CPU centric from my understanding of the ack mecanism...
Only a pair of CPUs are synchronized simultaneously, yes. But there
is absolutely no need to synchronize more than two at the same.
Besides, CPU2 is not started until CPU1 has booted...
/Samuel
** Sent via the linuxppc-dev mail list. See http://lists.linuxppc.org/
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH] 2.6 timebase synchronization
2003-08-09 1:13 ` Samuel Rydh
2003-08-09 8:58 ` Benjamin Herrenschmidt
@ 2003-08-10 2:09 ` Paul Mackerras
2003-08-10 9:39 ` Benjamin Herrenschmidt
1 sibling, 1 reply; 8+ messages in thread
From: Paul Mackerras @ 2003-08-10 2:09 UTC (permalink / raw)
To: Samuel Rydh; +Cc: linuxppc-dev
Samuel Rydh writes:
> Attached is an improved version of the patch.
How many SMP machines are there where we don't know how to freeze/thaw
the timebase? We know how to do that on the old powersurge powermacs,
on CHRP systems and on at least some of the recent core99 powermacs
(those that have a timebase-enable property on the cpu device nodes).
What machines are left?
Paul.
** Sent via the linuxppc-dev mail list. See http://lists.linuxppc.org/
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH] 2.6 timebase synchronization
2003-08-10 2:09 ` Paul Mackerras
@ 2003-08-10 9:39 ` Benjamin Herrenschmidt
2003-08-10 16:22 ` Mark Guertin
2003-08-10 21:29 ` Samuel Rydh
0 siblings, 2 replies; 8+ messages in thread
From: Benjamin Herrenschmidt @ 2003-08-10 9:39 UTC (permalink / raw)
To: Paul Mackerras; +Cc: Samuel Rydh, linuxppc-dev
On Sun, 2003-08-10 at 04:09, Paul Mackerras wrote:
> Samuel Rydh writes:
>
> > Attached is an improved version of the patch.
>
> How many SMP machines are there where we don't know how to freeze/thaw
> the timebase? We know how to do that on the old powersurge powermacs,
> on CHRP systems and on at least some of the recent core99 powermacs
> (those that have a timebase-enable property on the cpu device nodes).
> What machines are left?
We know how to do it on some core99, though we don't actually do it
yet ;) We use software sync on all core99 for now.
Remaining are some older core99 machines, the 4-way DayStar oldworld
machines, and afaik, that's all...
Ben.
** Sent via the linuxppc-dev mail list. See http://lists.linuxppc.org/
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH] 2.6 timebase synchronization
2003-08-10 9:39 ` Benjamin Herrenschmidt
@ 2003-08-10 16:22 ` Mark Guertin
2003-08-10 21:29 ` Samuel Rydh
1 sibling, 0 replies; 8+ messages in thread
From: Mark Guertin @ 2003-08-10 16:22 UTC (permalink / raw)
To: Untitled; +Cc: Paul Mackerras, Benjamin Herrenschmidt
On 8/10/03 5:39 AM, "Benjamin Herrenschmidt" <benh@kernel.crashing.org>
wrote:
> Remaining are some older core99 machines, the 4-way DayStar oldworld
> machines, and afaik, that's all...
As always, my Daystar quad is around, and if you want/need testing on it
just let me know. I also have a couple of Powersurge 2-way as well.
Mark (Gerk)
** Sent via the linuxppc-dev mail list. See http://lists.linuxppc.org/
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH] 2.6 timebase synchronization
2003-08-10 9:39 ` Benjamin Herrenschmidt
2003-08-10 16:22 ` Mark Guertin
@ 2003-08-10 21:29 ` Samuel Rydh
1 sibling, 0 replies; 8+ messages in thread
From: Samuel Rydh @ 2003-08-10 21:29 UTC (permalink / raw)
To: Benjamin Herrenschmidt; +Cc: linuxppc-dev, Paul Mackerras
On Sun, Aug 10, 2003 at 11:39:08AM +0200, Benjamin Herrenschmidt wrote:
>
> On Sun, 2003-08-10 at 04:09, Paul Mackerras wrote:
> > Samuel Rydh writes:
> >
> > > Attached is an improved version of the patch.
> >
> > How many SMP machines are there where we don't know how to freeze/thaw
> > the timebase? We know how to do that on the old powersurge powermacs,
> > on CHRP systems and on at least some of the recent core99 powermacs
> > (those that have a timebase-enable property on the cpu device nodes).
> > What machines are left?
>
> We know how to do it on some core99, though we don't actually do it
> yet ;) We use software sync on all core99 for now.
Btw, the freeze/thaw timebase setting that is done on psurge is lost
since the generic timebase calibration mechanism is still invoked
afterwards (and at that time, the timebases are ticking).
/Samuel
** Sent via the linuxppc-dev mail list. See http://lists.linuxppc.org/
^ permalink raw reply [flat|nested] 8+ messages in thread
end of thread, other threads:[~2003-08-10 21:29 UTC | newest]
Thread overview: 8+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2003-08-08 0:15 [PATCH] 2.6 timebase synchronization Samuel Rydh
2003-08-09 1:13 ` Samuel Rydh
2003-08-09 8:58 ` Benjamin Herrenschmidt
2003-08-09 11:48 ` Samuel Rydh
2003-08-10 2:09 ` Paul Mackerras
2003-08-10 9:39 ` Benjamin Herrenschmidt
2003-08-10 16:22 ` Mark Guertin
2003-08-10 21:29 ` Samuel Rydh
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