Messages in this thread | | | Date | Mon, 10 Oct 2011 01:08:22 +0530 | From | "Srivatsa S. Bhat" <> | Subject | Re: [PATCH] CPU hotplug,x86 Microcode: Don't request microcode from userspace unnecessarily |
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On 10/09/2011 04:57 PM, Borislav Petkov wrote: > On Sat, Oct 08, 2011 at 04:47:53PM -0400, Srivatsa S. Bhat wrote: >> Requesting the microcode from userspace *every time* when onlining CPUs >> (during a CPU hotplug operation) is unnecessary. >> >> So, this patch ensures that once the kernel gets the microcode after booting, >> it is not freed nor invalidated when a CPU goes offline, so that it can be >> reused when that CPU comes back online, without requesting userspace for it >> again. As a result, the CPU hotplug operations become faster as well. >> >> Tested-by: Borislav Petkov <bp@amd64.org> >> Acked-by: Borislav Petkov <bp@amd64.org> >> Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com> > > Good, thanks. Just a minor nitpick below. > >> --- >> >> arch/x86/kernel/microcode_core.c | 8 +++++++- >> 1 files changed, 7 insertions(+), 1 deletions(-) >> >> diff --git a/arch/x86/kernel/microcode_core.c b/arch/x86/kernel/microcode_core.c >> index f924280..3fd0189 100644 >> --- a/arch/x86/kernel/microcode_core.c >> +++ b/arch/x86/kernel/microcode_core.c >> @@ -483,7 +483,13 @@ mc_cpu_callback(struct notifier_block *nb, unsigned long action, void *hcpu) >> sysfs_remove_group(&sys_dev->kobj, &mc_attr_group); >> pr_debug("CPU%d removed\n", cpu); >> break; >> - case CPU_DEAD: >> + >> + /* When a CPU goes offline, don't free up or invalidate the copy of >> + * the microcode in kernel memory, so that we can reuse it when the >> + * CPU comes back online without unnecessarily requesting the userspace >> + * for it again. >> + */ >> + > > Kernel comment style is in this format: > > /* > * Blabla > * blublu > */ > Oh, ok.. Thank you for pointing it out.
> @Ingo, can you please adjust it in-flight when applying?
I'll post the patch with the correct comment style, if that would make things easier. -- Regards, Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com> Linux Technology Center, IBM India Systems and Technology Lab
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