Subject: Re: [PATCH] powerpc/mm: Add trace point for tracking hash pte fault

From: "Aneesh Kumar K.V" <[email-masked]>
Date: Mon, 02 Feb 2015 21:51:55 +0530

Anton Blanchard <[email-masked]> writes:

> Hi,
>
>> > ebizzy with -S 30 -t 1 -P gave
>> > 13627 records/s -> Without patch
>> > 13546 records/s -> With patch with tracepoint disabled
>> 
>> OK. So that's about -0.6%. Are we happy with that? I'm not sure.
>> 
>> Can you do a few more runs and see if that's a stable result.
>
> Surprisingly large. Is CONFIG_JUMP_LABEL enabled? That should reduce the
> tracepoint to just a nop.

yes. We do use jump label. I also verified that looking at .s

#APP
 # 23 "./arch/powerpc/include/asm/jump_label.h" 1
        1:
        nop
        .pushsection __jump_table,  "aw"
        .llong 1b, .L201, __tracepoint_hash_fault+8      #,
        .popsection

 # 0 "" 2
.....

-aneesh