From: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
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@xxxxxxxxxxxxxxxxxxxx>
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.
Cc: Rusty Russell <rusty@xxxxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxx>
Cc: Venkatesh Pallipadi <venkatesh.pallipadi@xxxxxxxxx>
Cc: Len Brown <len.brown@xxxxxxxxx>
Cc: Zhao Yakui <yakui.zhao@xxxxxxxxx>
Cc: Dave Jones <davej@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Tested-by: Mike Galbraith <efault@xxxxxx>
Cc: "Zhang, Yanmin" <yanmin_zhang@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
arch/x86/kernel/cpu/cpufreq/acpi-cpufreq.c | 25 ++++++++-----------
1 file changed, 11 insertions(+), 14 deletions(-)
diff -puN arch/x86/kernel/cpu/cpufreq/acpi-cpufreq.c~arch-x86-kernel-cpu-cpufreq-acpi-cpufreqc-avoid-using-work_on_cpu arch/x86/kernel/cpu/cpufreq/acpi-cpufreq.c
--- a/arch/x86/kernel/cpu/cpufreq/acpi-cpufreq.c~arch-x86-kernel-cpu-cpufreq-acpi-cpufreqc-avoid-using-work_on_cpu
+++ a/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)
@@ -252,15 +251,13 @@ 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 +280,7 @@ 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, &cur, 1))
return 0;
cur.aperf.whole = readin.aperf.whole -
_
--
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