Messages in this thread Patch in this message | | | From | Rusty Russell <> | Date | Mon, 13 Apr 2009 09:30:02 +0930 | Subject | [PATCH 1/7] use smp_call_function_single() in arch/x86/kernel/cpu/cpufreq/acpi-cpufreq.c |
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From: Andrew Morton <akpm@linux-foundation.org>
Impact: fix sysbench(oltp)+mysql 10% regression with 2.6.30-rc1
Mike says: It's kondemand, do_dbs_timer() is queueing work 9-14 times/sec/cpu.
Tested-by: Mike Galbraith <efault@gmx.de> Cc: Ingo Molnar <mingo@elte.hu> Cc: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com> Cc: Len Brown <len.brown@intel.com> Cc: Zhao Yakui <yakui.zhao@intel.com> Cc: Dave Jones <davej@redhat.com> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> (use rdmsr_on_cpu) --- arch/x86/kernel/cpu/cpufreq/acpi-cpufreq.c | 24 +++++++++++------------- 1 file changed, 11 insertions(+), 13 deletions(-)
diff --git a/arch/x86/kernel/cpu/cpufreq/acpi-cpufreq.c b/arch/x86/kernel/cpu/cpufreq/acpi-cpufreq.c --- a/arch/x86/kernel/cpu/cpufreq/acpi-cpufreq.c +++ b/arch/x86/kernel/cpu/cpufreq/acpi-cpufreq.c @@ -153,7 +153,8 @@ struct drv_cmd { u32 val; }; -static long do_drv_read(void *_cmd) +/* Called via smp_call_function_single(), on the target CPU */ +static void do_drv_read(void *_cmd) { struct drv_cmd *cmd = _cmd; u32 h; @@ -170,10 +171,10 @@ static long do_drv_read(void *_cmd) default: break; } - return 0; } -static long do_drv_write(void *_cmd) +/* Called via smp_call_function_single(), on the target CPU */ +static void do_drv_write(void *_cmd) { struct drv_cmd *cmd = _cmd; u32 lo, hi; @@ -192,23 +193,21 @@ static long do_drv_write(void *_cmd) default: break; } - return 0; } static void drv_read(struct drv_cmd *cmd) { cmd->val = 0; - work_on_cpu(cpumask_any(cmd->mask), do_drv_read, cmd); + smp_call_function_single(cpumask_any(cmd->mask), do_drv_read, cmd, 1); } static void drv_write(struct drv_cmd *cmd) { - unsigned int i; + unsigned int cpu; - for_each_cpu(i, cmd->mask) { - work_on_cpu(i, do_drv_write, cmd); - } + for_each_cpu(cpu, cmd->mask) + smp_call_function_single(cpu, do_drv_write, cmd, 1); } static u32 get_cur_val(const struct cpumask *mask) @@ -253,14 +252,13 @@ struct perf_pair { }; -static long read_measured_perf_ctrs(void *_cur) +/* Called via smp_call_function_single(), on the target CPU */ +static void read_measured_perf_ctrs(void *_cur) { struct perf_pair *cur = _cur; rdmsr(MSR_IA32_APERF, cur->aperf.split.lo, cur->aperf.split.hi); rdmsr(MSR_IA32_MPERF, cur->mperf.split.lo, cur->mperf.split.hi); - - return 0; } /* @@ -283,7 +281,7 @@ static unsigned int get_measured_perf(st unsigned int perf_percent; unsigned int retval; - if (!work_on_cpu(cpu, read_measured_perf_ctrs, &readin)) + if (!smp_call_function_single(cpu, read_measured_perf_ctrs, &readin, 1)) return 0; cur.aperf.whole = readin.aperf.whole -
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