The patch titled
arch/x86/kernel/cpu/cpufreq/acpi-cpufreq.c: avoid cross-CPU interrupts
has been added to the -mm tree. Its filename is
arch-x86-kernel-cpu-cpufreq-acpi-cpufreqc-avoid-cross-cpu-interrupts.patch
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/SubmitChecklist when testing your code ***
See http://userweb.kernel.org/~akpm/stuff/added-to-mm.txt to find
out what to do about this
The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/
------------------------------------------------------
Subject: arch/x86/kernel/cpu/cpufreq/acpi-cpufreq.c: avoid cross-CPU interrupts
From: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
In drv_read(), check to see whether we can run the rdmsr() on the current
CPU. If so, do that. So smp_call_function_single() can avoid the IPI.
Arguably, cpumask_any() should do this.
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>
Cc: Mike Galbraith <efault@xxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
arch/x86/kernel/cpu/cpufreq/acpi-cpufreq.c | 17 +++++++++++++++--
1 file changed, 15 insertions(+), 2 deletions(-)
diff -puN arch/x86/kernel/cpu/cpufreq/acpi-cpufreq.c~arch-x86-kernel-cpu-cpufreq-acpi-cpufreqc-avoid-cross-cpu-interrupts 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-cross-cpu-interrupts
+++ a/arch/x86/kernel/cpu/cpufreq/acpi-cpufreq.c
@@ -197,9 +197,22 @@ static void do_drv_write(void *_cmd)
static void drv_read(struct drv_cmd *cmd)
{
- cmd->val = 0;
+ int target_cpu; /* The CPU on which to perform thr rdmsr() */
+ int this_cpu;
+
+ /*
+ * If the current CPU is in cmd->mask then run the rdmsr() on this
+ * CPU to avoid the cross-cpu interrupt.
+ */
+ this_cpu = get_cpu();
+ if (cpu_isset(this_cpu, *(cmd->mask)))
+ target_cpu = this_cpu;
+ else
+ target_cpu = cpumask_any(cmd->mask);
- smp_call_function_single(cpumask_any(cmd->mask), do_drv_read, cmd, 1);
+ cmd->val = 0;
+ smp_call_function_single(target_cpu, do_drv_read, cmd, 1);
+ put_cpu();
}
static void drv_write(struct drv_cmd *cmd)
_
Patches currently in -mm which might be from akpm@xxxxxxxxxxxxxxxxxxxx are
origin.patch
i2c-too-much-compiler-noise.patch
linux-next.patch
next-remove-localversion.patch
i-need-old-gcc.patch
toshiba_acpi-add-full-hotkey-support-fix.patch
arch-x86-kernel-cpu-cpufreq-acpi-cpufreqc-avoid-using-work_on_cpu.patch
arch-x86-kernel-cpu-cpufreq-acpi-cpufreqc-avoid-cross-cpu-interrupts.patch
early-platform-driver-v3.patch
clocksource-pass-clocksource-to-read-callback.patch
input-bcm5974-declare-alignment-usage.patch
input-keyboard-introduce-lm8323-driver.patch
drivers-input-xpadc-improve-xbox-360-wireless-support-and-add-sysfs-interface-checkpatch-fixes.patch
input-documentation-input-xpadtxt-update-for-new-driver-functionality-checkpatch-fixes.patch
mtd-flex-onenand-support.patch
misdn-l1oip-reduce-stack-memory-footprint.patch
drivers-net-82596c-suppress-warnings.patch
pci-quirks-unhide-overflow-device-on-i828675p-pe-chipsets-v2.patch
raw-fix-rawctl-compat-ioctls-breakage-on-amd64-and-itanic.patch
libfs-make-simple_read_from_buffer-conventional.patch
xtensa-add-flat-support-checkpatch-fixes.patch
hfs-fix-memory-leak-when-unmounting-fix.patch
memcg-remove-warning-when-config_debug_vm=n-fix.patch
scsi-dpt_i2o-is-bust-on-ia64.patch
input-add-a-dmi-table-for-the-i8042reset-option-make-msi-wind-u-100-work.patch
mm-consolidate-init_mm-definition-fix.patch
frv-duplicate-output_buffer-of-e03-checkpatch-fixes.patch
m68k-count-can-reach-51-not-50.patch
flat-fix-data-sections-alignment.patch
gru-support-for-asynchronous-gru-instructions-fix.patch
reiser4-export-remove_from_page_cache-fix.patch
reiser4.patch
reiser4-remove-simple_prepare_write-usage-checkpatch-fixes.patch
slab-leaks3-default-y.patch
put_bh-debug.patch
shrink_slab-handle-bad-shrinkers.patch
getblk-handle-2tb-devices.patch
getblk-handle-2tb-devices-fix.patch
undeprecate-pci_find_device.patch
notify_change-callers-must-hold-i_mutex.patch
drivers-net-bonding-bond_sysfsc-suppress-uninitialized-var-warning.patch
--
To unsubscribe from this list: send the line "unsubscribe mm-commits" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
