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[PATCH] i386: i386 make NMI use PERFCTR1 for architectural perfmon (take 2)

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Hello,

This patch against 2.6.20-git14 makes the NMI watchdog use PERFSEL1/PERFCTR1
instead of PERFSEL0/PERFCTR0 on processors supporting Intel architectural
perfmon, such as Intel Core 2. Although all PMU events can work on
both counters, the Precise Event-Based Sampling (PEBS) requires that the
event be in PERFCTR0 to work correctly (see section 18.14.4.1 in the
IA32 SDM Vol 3b).

A similar patch for x86-64 is to follow.

Changelog:
        - make the i386 NMI watchdog use PERFSEL1/PERFCTR1 instead of PERFSEL0/PERFCTR0
          on processors supporting the Intel architectural perfmon (e.g. Core 2 Duo).
          This allows PEBS to work when the NMI watchdog is active.

signed-off-by: stephane eranian <eranian@hpl.hp.com>

Signed-off-by: Andi Kleen <ak@suse.de>
This commit is contained in:
Stephane Eranian 2007-05-02 19:27:05 +02:00 committed by Andi Kleen
parent 803d80f650
commit bf8696ed6d
1 changed files with 4 additions and 4 deletions
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8
arch/i386/kernel/nmi.c
View file

@ -365,7 +365,7 @@ static int __init check_nmi_watchdog(void)
nmi_hz = 1;
if (wd->perfctr_msr == MSR_P6_PERFCTR0 ||
wd->perfctr_msr == MSR_ARCH_PERFMON_PERFCTR0) {
wd->perfctr_msr == MSR_ARCH_PERFMON_PERFCTR1) {
nmi_hz = adjust_for_32bit_ctr(nmi_hz);
}
}
@ -799,8 +799,8 @@ static int setup_intel_arch_watchdog(void)
(ebx & ARCH_PERFMON_UNHALTED_CORE_CYCLES_PRESENT))
goto fail;
perfctr_msr = MSR_ARCH_PERFMON_PERFCTR0;
evntsel_msr = MSR_ARCH_PERFMON_EVENTSEL0;
perfctr_msr = MSR_ARCH_PERFMON_PERFCTR1;
evntsel_msr = MSR_ARCH_PERFMON_EVENTSEL1;
if (!__reserve_perfctr_nmi(-1, perfctr_msr))
goto fail;
@ -1080,7 +1080,7 @@ __kprobes int nmi_watchdog_tick(struct pt_regs * regs, unsigned reason)
write_watchdog_counter(wd->perfctr_msr, NULL);
}
else if (wd->perfctr_msr == MSR_P6_PERFCTR0 ||
wd->perfctr_msr == MSR_ARCH_PERFMON_PERFCTR0) {
wd->perfctr_msr == MSR_ARCH_PERFMON_PERFCTR1) {
/* P6 based Pentium M need to re-unmask
* the apic vector but it doesn't hurt
* other P6 variant.