2006-10-05 00:03:49

by Ananiev, Leonid I

[permalink] [raw]
Subject: RE: [PATCH] mm: balance dirty pages

The throughput of iozone benchmark is changed as

serial random
write -55% -99%
read +60% +13%

after "[PATCH] mm: balance dirty pages".
iozone is running with option -B (using mmap) for file size 120% of RAM.

Leonid


2006-10-05 03:50:19

by Andrew Morton

[permalink] [raw]
Subject: Re: [PATCH] mm: balance dirty pages

On Thu, 5 Oct 2006 04:03:35 +0400
"Ananiev, Leonid I" <[email protected]> wrote:

> The throughput of iozone benchmark is changed as
>
> serial random
> write -55% -99%
> read +60% +13%
>
> after "[PATCH] mm: balance dirty pages".
> iozone is running with option -B (using mmap) for file size 120% of RAM.
>

That is expected and intentional. Previously, `iozone -B' was able to
swamp the whole machine with dirty memory. That gives good benchmark
numbers, but causes everything else on the machine to be adversely
affected.

The new behaviour will punish iozone for being bad, and will hopefully
cause less damage to other applications.