lkml.org 
[lkml]   [2017]   [Jun]   [19]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH v3 1/n] perf/core: addressing 4x slowdown during per-process profiling of STREAM benchmark on Intel Xeon Phi
On Mon, Jun 19, 2017 at 04:24:01PM +0100, Mark Rutland wrote:
> On Mon, Jun 19, 2017 at 08:21:51AM -0700, Andi Kleen wrote:
> > > I was trying to get a feel for how that compares to what we can do
> > > today. For other reasons (e.g. fd exhaustion), opening NR_CPUS * n
> >
> > You just have to increase the fd limit. The 1024 fd default is just
> > archaic for larger systems and doesn't really make any sense because
> > it only controls very small amounts of kernel memory.
> >
> > > events might not be a great idea on systems with a huge number of CPUs.
> > > We might want a heuristic in the perf tool regardless.
> >
> > But there's no alternative: we have to measure all CPUs with all events.
>
> You can measure the process on all CPUs by using 1 event without a CPU
> filter, rather than NR_CPUS events.

That wouldn't measure all threads, at least not with current perf core.

-Andi

\
 
 \ /
  Last update: 2017-06-19 17:41    [W:0.307 / U:0.304 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site