lkml.org 
[lkml]   [2018]   [Sep]   [23]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH 47/48] perf record: Spread maps for --threads option
On Mon, Sep 17, 2018 at 08:40:48PM +0900, Namhyung Kim wrote:
> On Thu, Sep 13, 2018 at 02:54:49PM +0200, Jiri Olsa wrote:
> > Currently we assign all maps to main thread. Adding
> > code that spreads maps for --threads option.
> >
> > For --thread option we create as many threads as there
> > are memory maps in evlist, which is the number of CPUs
> > in the system or CPUs we monitor. Each thread gets a
> > single data mmap to read.
> >
> > In addition we have also same amount of tracking mmaps
> > for auxiliary events which we don't create special thread
> > for. Instead we assign the to the main thread, because
> > there's not much traffic expected there.
> >
> > The assignment is visible from --thread-stats output:
> >
> > pid write poll skip maps (size 20K)
> > 1s 9770 144B 1 0 19K 19K 19K 18K 19K
> > 9772 0B 1 0 18K
> > 9773 0B 1 0 19K
> > 9774 0B 1 0 19K
> >
> > There are 5 maps for thread 9770 (1 data map and 4 auxiliary)
> > and one data map for every other thread. Each thread writes
> > data to the separate data file.
>
> Hmm.. not sure it'll work well for large machines with 1000+ cpus.
> What about giving each thread a data mmap and a tracking mmap?

well currently we store the tracking data in single file,
thats why we need just one thread to write them down

with the *_time API, we should be able to properly read the
tracking data separately for each cpu

jirka

\
 
 \ /
  Last update: 2018-09-23 21:45    [W:0.139 / U:1.824 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site