Messages in this thread | | | Subject | Re: [PATCH v2 4/4] nmi_backtrace: generate one-line reports for idle cpus | From | Chris Metcalf <> | Date | Mon, 21 Mar 2016 12:15:12 -0400 |
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On 03/21/2016 11:42 AM, Peter Zijlstra wrote: > On Wed, Mar 16, 2016 at 01:02:13PM -0400, Chris Metcalf wrote: >> diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c >> index 9f7c21c22477..d569ae7fde37 100644 >> --- a/arch/x86/kernel/process.c >> +++ b/arch/x86/kernel/process.c >> @@ -298,7 +298,7 @@ void arch_cpu_idle(void) >> /* >> * We use this if we don't have any better idle routine.. >> */ >> -void default_idle(void) >> +void __cpuidle default_idle(void) >> { >> trace_cpu_idle_rcuidle(1, smp_processor_id()); >> safe_halt(); >> @@ -413,7 +413,7 @@ static int prefer_mwait_c1_over_halt(const struct cpuinfo_x86 *c) >> * with interrupts enabled and no flags, which is backwards compatible with the >> * original MWAIT implementation. >> */ >> -static void mwait_idle(void) >> +static __cpuidle void mwait_idle(void) >> { >> if (!current_set_polling_and_test()) { >> trace_cpu_idle_rcuidle(1, smp_processor_id()); > The most common idle function for x86 is: mwait_idle_with_hints(), > trouble is, its an inline, so I'm not sure adding __cpuidle to it does > anything.
No, you're right, it wouldn't help. I didn't look at the drivers/cpuidle subsystem at all in my patch, since I'm not that familiar with it, but it seems like tagging acpi_processor_ffh_cstate_enter(), as the only user of mwait_idle_with_hints(), will do the job.
I do see that native_play_dead() also uses mwait/monitor, but since that's hotplug I don't think it's relevant to this patch series.
> I've yet to find the magic objdump incantation to check. Or rather > objdump -h doesn't appear to list .cpuidle.text at all :/ > > I'm probably doing something silly...
The easiest way to check for a given function is just to look at the "nm -n" output and see that all the functions you expect to reflect idle behavior are in the cpuidle begin/end range. Or, to look at "objdump -dr" and search for monitor/mwait.
objdump -h certainly works to show .cpuidle.text if you look at individual objects (e.g. arch/x86/kernel/process.o) but by the time you're looking at the linked vmlinux image they have all been linked into the giant .text section.
-- Chris Metcalf, Mellanox Technologies http://www.mellanox.com
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