lkml.org 
[lkml]   [2009]   [Oct]   [5]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
SubjectRe: [RFC PATCH] perf_core: provide a kernel-internal interface to get to performance counters
From
2009/10/5 Ingo Molnar <mingo@elte.hu>:
>
> * Peter Zijlstra <peterz@infradead.org> wrote:
>> Non-trivial.
>>
>> Something like this would imply a single output channel for all these
>> CPUs, and we've already seen that stuffing too many CPUs down one such
>> channel (using -M) leads to significant performance issues.
>
> We could add internal per cpu buffering before it hits any globally
> visible output channel. (That has come up when i talked to Frederic
> about the function tracer.) We could even have page sized output (via
> the introduction of a NOP event that fills up to the next page edge).


That looks good for the counting/sampling fast path, but would that scale
once it comes to reordering in the globally visible output channel?
Such a union has its costs.


\
 
 \ /
  Last update: 2009-10-05 11:33    [W:0.072 / U:0.092 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site