Re: [PATCH v1 1/2] perf,x86: add Intel RAPL PMU support

From: Ingo Molnar
Date: Tue Oct 08 2013 - 03:37:16 EST



* Andi Kleen <ak@xxxxxxxxxxxxxxx> wrote:

> On Mon, Oct 07, 2013 at 08:08:10PM +0200, Peter Zijlstra wrote:
> > On Mon, Oct 07, 2013 at 10:55:42AM -0700, Andi Kleen wrote:
> > > This would in principle allow making it a module later (if perf ever
> > > supports that)
> >
> > IIRC its a few EXPORTs away from being able to do that.
>
> Great. With ~700k text that would be a good thing.

Nonsense, the real overhead of core perf + PMU drivers on x86-64 is around
150k.

The 700k overhead you claimed is not reproducible, at all, and I tested it
with your own config:

https://lkml.org/lkml/2013/10/8/62

700k in perf is nonsensical - it's an obvious lie really, the code sizes
of the relevant perf .o objects are nowhere even _close_ to that amount:

hubble:~/tip> size $(find . -name '*perf*.o')
text data bss dec hex filename
887 0 32 919 397 ./arch/x86/kernel/cpu/perfctr-watchdog.o
2932 680 96 3708 e7c ./arch/x86/kernel/cpu/perf_event_amd_uncore.o
14117 6361 1 20479 4fff ./arch/x86/kernel/cpu/perf_event_intel.o
23787 19541 264 43592 aa48 ./arch/x86/kernel/cpu/perf_event_intel_uncore.o
4531 1572 0 6103 17d7 ./arch/x86/kernel/cpu/perf_event_p4.o
1728 1121 0 2849 b21 ./arch/x86/kernel/cpu/perf_event_knc.o
4591 811 32 5434 153a ./arch/x86/kernel/cpu/perf_event_amd_ibs.o
13394 6797 116 20307 4f53 ./arch/x86/kernel/cpu/perf_event.o
3156 1483 32 4671 123f ./arch/x86/kernel/cpu/perf_event_amd_iommu.o
5322 4396 0 9718 25f6 ./arch/x86/kernel/cpu/perf_event_intel_ds.o
11383 1 0 11384 2c78 ./arch/x86/kernel/cpu/perf_event_intel_lbr.o
3636 1125 0 4761 1299 ./arch/x86/kernel/cpu/perf_event_amd.o
1282 544 0 1826 722 ./arch/x86/kernel/cpu/perf_event_p6.o
278 1 0 279 117 ./arch/x86/kernel/perf_regs.o
4844 88 12 4944 1350 ./drivers/acpi/processor_perflib.o
77 96 0 173 ad ./drivers/cpufreq/cpufreq_performance.o
232 64 0 296 128 ./drivers/devfreq/governor_performance.o
1972 4 64 2040 7f8 ./kernel/trace/trace_event_perf.o

So stop making that ridiculous claim without posting exact .config's
publicly.

Thanks,

Ingo
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