Re: [PATCH v2 0/2] Replace PID bitmap allocation with IDR API

[Rik van Riel]

On Fri, 2017-09-29 at 01:35 +0530, Gargi Sharma wrote:
> On Thu, Sep 28, 2017 at 3:46 PM, Rik van Riel <riel@xxxxxxxxxxx>
> wrote:
> > On Fri, 2017-09-29 at 01:09 +0530, Gargi Sharma wrote:
> > 
> > > 1000 processes that just sleep and sit around without doing
> > > anything(100 second sleep and then exit).
> > 
> > Is that with or without your patches?
> > 
> > How does it compare to a kernel with(out) your patches?
> 
> Ah thanks for pointing this out. Those were without the patches.
> Here are the stats for easier comparison.
> 
> With PatchesÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂWithout patches
> pstree
> realÂÂÂÂ0m0.542sÂÂÂÂÂÂÂÂÂÂÂÂrealÂÂÂÂ0m0.859s
> userÂÂÂÂ0m0.335sÂÂÂÂÂÂÂÂÂÂÂuserÂÂÂÂ0m0.536s
> sysÂÂÂÂ0m0.150sÂÂÂÂÂÂÂÂÂÂÂÂÂsysÂÂÂÂ0m0.172s
> 
> ps
> realÂÂÂÂ0m0.722sÂÂÂÂÂÂÂÂÂÂÂÂrealÂÂÂÂ0m0.918s
> userÂÂÂÂ0m0.064sÂÂÂÂÂÂÂÂÂÂÂuserÂÂÂÂ0m0.100s
> sysÂÂÂÂ0m0.162sÂÂÂÂÂÂÂÂÂÂÂÂÂsysÂÂÂÂ0m0.172s
> 
> readdir
> realÂÂÂÂ0m0.080sÂÂÂÂÂÂÂÂÂÂÂrealÂÂÂÂ0m0.092s
> userÂÂÂÂ0m0.000sÂÂÂÂÂÂÂÂÂÂuserÂÂÂÂ0m0.000s
> sysÂÂÂÂ0m0.021sÂÂÂÂÂÂÂÂÂÂÂÂsysÂÂÂÂ0m0.020s

So your patches speed up the use of /proc?

I suspect pstree and ps benefit from the simplification
and speedup of find_pid_ns, which is called from
find_task_by_pid_ns.

That is great news.

-- 
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