[2.6.20.16 review 01/28] i386: Fix K8/core2 oprofile on multiple CPUs

From: Willy Tarreau
Date: Sat Aug 11 2007 - 14:58:56 EST


Only try to allocate MSRs once instead of for every CPU.

This assumes the MSRs are the same on all CPUs which is currently
true. P4-HT is a special case for different SMT threads, but the code
always saves/restores all MSRs so it works identical.

Signed-off-by: Andi Kleen <ak@xxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Chris Wright <chrisw@xxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>
---
arch/i386/oprofile/nmi_int.c | 9 ++++++++-
1 files changed, 8 insertions(+), 1 deletions(-)

diff --git a/arch/i386/oprofile/nmi_int.c b/arch/i386/oprofile/nmi_int.c
index 3700eef..be4a9a8 100644
--- a/arch/i386/oprofile/nmi_int.c
+++ b/arch/i386/oprofile/nmi_int.c
@@ -131,7 +131,6 @@ static void nmi_save_registers(void * dummy)
{
int cpu = smp_processor_id();
struct op_msrs * msrs = &cpu_msrs[cpu];
- model->fill_in_addresses(msrs);
nmi_cpu_save_registers(msrs);
}

@@ -195,6 +194,7 @@ static struct notifier_block profile_exceptions_nb = {
static int nmi_setup(void)
{
int err=0;
+ int cpu;

if (!allocate_msrs())
return -ENOMEM;
@@ -207,6 +207,13 @@ static int nmi_setup(void)
/* We need to serialize save and setup for HT because the subset
* of msrs are distinct for save and setup operations
*/
+
+ /* Assume saved/restored counters are the same on all CPUs */
+ model->fill_in_addresses(&cpu_msrs[0]);
+ for_each_possible_cpu (cpu) {
+ if (cpu != 0)
+ cpu_msrs[cpu] = cpu_msrs[0];
+ }
on_each_cpu(nmi_save_registers, NULL, 0, 1);
on_each_cpu(nmi_cpu_setup, NULL, 0, 1);
nmi_enabled = 1;
--
1.5.2.4

--
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