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SubjectRe: [PATCH -mm 00/24] VM pageout scalability improvements (V12)
On Wed, 11 Jun 2008 22:34:30 -0700
Andrew Morton <akpm@linux-foundation.org> wrote:

> On a 900MB 2-way, allocate and memset 1000MB.

> Seems to have saved a little CPU but the IO patterns got worse.

In previous tests on my 16GB system, a 16GB fillmem (goes into swap)
saves enough CPU time to make up for potentially worse detection of
the working set (well, not like this program really has a working set).

I'll try this out myself on a smaller system and see if there's
something I can do to make it better.

> qsbench, 4 processes, memory size tuned to threshold-of-swapping*1.1:
>
> Mainline:
>
> vmm:/home/akpm/qsbench> time ./qsbench -p 4 -m 230
> ./qsbench -p 4 -m 230 175.45s user 45.67s system 60% cpu 6:08.40 total
>
> 2.6.26-rc5-mm3:
>
> vmm:/home/akpm/qsbench> time ./qsbench -p 4 -m 230
> ./qsbench -p 4 -m 230 178.21s user 28.49s system 99% cpu 3:27.14 total
>
> So woot! Professional qsbench users will be pleased ;) It could have
> been a fluke though - iirc qsbench is pretty unstable, especially on
> the threshold.

Ignoring references that happen on the active list, only acting
on re-references that happen on the inactive list, gives anonymous
memory something that closer resembles the use-once policy.

Better for some workloads, but potentially worse for others.

Definately worth tweaking the system though, to get performance
as close to where we want it as possible :)

> Main thing is: it seems stable. Old LTP ran for an hour or so before I
> hit the msgctl08 crash (which is a regression in current mainline).

Our main focus has been on stability for the past few months,
trying to get the whole series integrated.

--
All rights reversed.


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