Re: [PATCH 2/3] perf tools: Cache dso data file descriptor

From: Ingo Molnar
Date: Wed May 07 2014 - 15:01:24 EST



* Jiri Olsa <jolsa@xxxxxxxxxx> wrote:

> On Sun, Apr 27, 2014 at 11:36:35PM +0900, Namhyung Kim wrote:
> > 2014-04-17 (ë), 19:39 +0200, Jiri Olsa:
> > > Keeping the data file description open for the whole life
> > > of the dso object.
> >
> > I suspect there might be an issue for reporting very large data file
> > with this approach - like open file limit?
>
> I've got as high as ~200 openned file descriptors for
> ~2GB data of system wide monitoring

Note that 200 open file descriptors in themselves are not a
scalability problem on Linux, as long as perf doesn't walk them
linearly anywhere.

I think we are reasonably fast even with a million open files in a
singe process, or so.

Thanks,

Ingo
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