Re: missing madvise functionality

[Rik van Riel]

Andrew Morton wrote:
> On Thu, 05 Apr 2007 03:39:29 -0400 Rik van Riel <riel@xxxxxxxxxx> wrote:
>
> > Rik van Riel wrote:
> >
> > > MADV_DONTNEED, unpatched, 1000 loops
> > >
> > > real    0m13.672s
> > > user    0m1.217s
> > > sys     0m45.712s
> > >
> > >
> > > MADV_DONTNEED, with patch, 1000 loops
> > >
> > > real    0m4.169s
> > > user    0m2.033s
> > > sys     0m3.224s
> > I just noticed something fun with these numbers.
> >
> > Without the patch, the system (a quad core CPU) is 10% idle.
> >
> > With the patch, it is 66% idle - presumably I need Nick's
> > mmap_sem patch.
> >
> > However, despite being 66% idle, the test still runs over
> > 3 times as fast!
>
> Please quote the context switch rate when testing this stuff (I use vmstat 1).
> I've seen it vary by a factor of 10,000 depending upon what's happening.

About context switches 14000 per second.

I'll go compile in Nick's patch to see if that makes
things go faster.  I expect it will.

procs -----------memory---------- ---swap-- -----io---- --system-- 
-----cpu------
 r  b   swpd   free   buff  cache   si   so    bi    bo   in   cs us sy 
id wa st
 1  0      0 965232 250024 370848    0    0     0     0 1026 13914 13 
21 67  0  0
 1  0      0 965232 250024 370848    0    0     0     0 1018 14654 12 
20 68  0  0
 1  0      0 965232 250024 370848    0    0     0     0 1023 14006 12 
21 67  0  0


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