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authorAndrew Morton <akpm@linux-foundation.org>2009-04-13 10:27:49 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2009-04-13 11:09:46 -0700
commit01599fca6758d2cd133e78f87426fc851c9ea725 (patch)
tree26a3f1d69c955de2c5388e5855dfe4ff3ff8687b /arch/x86/kernel/cpu
parent8371f87c9994d9942af5984309835aeb948ba579 (diff)
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 <akpm@linux-foundation.org> 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 <rusty@rustcorp.com.au> Cc: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com> Cc: Len Brown <len.brown@intel.com> Cc: Zhao Yakui <yakui.zhao@intel.com> Acked-by: Dave Jones <davej@redhat.com> Cc: Thomas Gleixner <tglx@linutronix.de> Tested-by: Mike Galbraith <efault@gmx.de> Cc: "Zhang, Yanmin" <yanmin_zhang@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Ingo Molnar <mingo@elte.hu> [ Made it use smp_call_function_many() instead of looping over cpu's with smp_call_function_single() - Linus ] Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'arch/x86/kernel/cpu')
-rw-r--r--arch/x86/kernel/cpu/cpufreq/acpi-cpufreq.c24
1 files 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 9d3af380c6b..3e3cd3db7a0 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 -