From 01599fca6758d2cd133e78f87426fc851c9ea725 Mon Sep 17 00:00:00 2001 From: Andrew Morton Date: Mon, 13 Apr 2009 10:27:49 -0700 Subject: [PATCH] cpufreq: use smp_call_function_[single|many]() in acpi-cpufreq.c Atttempting to rid us of the problematic work_on_cpu(). Just use smp_call_fuction_single() here. This repairs a 10% sysbench(oltp)+mysql regression which Mike reported, due to commit 6b44003e5ca66a3fffeb5bc90f40ada2c4340896 Author: Andrew Morton Date: Thu Apr 9 09:50:37 2009 -0600 work_on_cpu(): rewrite it to create a kernel thread on demand It seems that the kernel calls these acpi-cpufreq functions at a quite high frequency. Valdis Kletnieks also reports that this causes 70-90 forks per second on his hardware. Cc: Valdis.Kletnieks@vt.edu Cc: Rusty Russell Cc: Venkatesh Pallipadi Cc: Len Brown Cc: Zhao Yakui Acked-by: Dave Jones Cc: Thomas Gleixner Tested-by: Mike Galbraith Cc: "Zhang, Yanmin" Signed-off-by: Andrew Morton Acked-by: Ingo Molnar [ Made it use smp_call_function_many() instead of looping over cpu's with smp_call_function_single() - Linus ] Signed-off-by: Linus Torvalds --- arch/x86/kernel/cpu/cpufreq/acpi-cpufreq.c | 24 +++++++++--------------- 1 file changed, 9 insertions(+), 15 deletions(-) diff --git a/arch/x86/kernel/cpu/cpufreq/acpi-cpufreq.c b/arch/x86/kernel/cpu/cpufreq/acpi-cpufreq.c index 9d3af38..3e3cd3d 100644 --- 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_many(), on the target CPUs */ +static void do_drv_write(void *_cmd) { struct drv_cmd *cmd = _cmd; u32 lo, hi; @@ -192,23 +193,18 @@ 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; - - for_each_cpu(i, cmd->mask) { - work_on_cpu(i, do_drv_write, cmd); - } + smp_call_function_many(cmd->mask, do_drv_write, cmd, 1); } static u32 get_cur_val(const struct cpumask *mask) @@ -252,15 +248,13 @@ struct perf_pair { } aperf, mperf; }; - -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 +277,7 @@ static unsigned int get_measured_perf(struct cpufreq_policy *policy, 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, &cur, 1)) return 0; cur.aperf.whole = readin.aperf.whole - -- 2.7.4