Re: [PATCH 00/23] per device dirty throttling -v8

[richard kennedy]

On Fri, 2007-08-03 at 14:37 +0200, Peter Zijlstra wrote:
> Per device dirty throttling patches
> 
> These patches aim to improve balance_dirty_pages() and directly address three
> issues:
>   1) inter device starvation
>   2) stacked device deadlocks
>   3) inter process starvation
<snip>
Hi Peter,
I've been testing your patch with a simple test case that copies a 3GB
file from sda -> sda, and copies a 1GB file from sda -> sdb.
the script is roughly this :-

dd bs=64k if=[sda]/data3g of=[sda]/temp_data3g &
sleep 60
dd bs=64k if=[sda]/data1g of=[sdb]/temp_data1g &
wait
sleep 200

On my amd64x2 desktop machine where sda is a sata 250 GB drive & sdb is
an ide 300 GB drive.

Running this test 5 times gives
2.6.23-rc1-mm2
1GB copy MB/s	3GB copy MB/s
16.2		16.1
15.2		14.6
17.3		14.6
18.0		14.5
19.0		14.6

2.6.23-rc1-mm2+pddt_patch
1GB copy MB/s	3GB copy MB/s
23.0		14.7
24.0		14.6
20.4		14.8
22.6		14.5
23.2		14.5

This is on a standard desktop machine so there are lots of other
processes running on it, and although there is a degree of variability
in the numbers,they are very repeatable and your patch always out
performs the stock mm2.
looks good to me

Richard
  






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