Re: [PATCH 00/23] per device dirty throttling -v10

From: Tobias Oetiker
Date: Thu Sep 13 2007 - 19:43:38 EST


Peter,

I have been using your -v9 backport to 2.6.22 (thanks very much
btw) for the last few days on an amd64 system configured like this:

[/],[/home],[/backup],...
on top of
[lvm2]
using
[/dev/sdb]
which is an
[areca hw raid 6 device made up from 8 sata disks]

With your patch, performance was much improved. But still there are
some seemingly simple tasks which do not work well. Like

cp /home/bigfile.txt /backup/bigfile.txt

or also

rm -r /backup/big-directory

They both affect disk access times of other processes very badly.

As I said, things improved a quite a bit with your patch, but I wonder
if there is more that could be done for this particular setup?

A second thing. Since my box has 8GB memory, I am intrigued by the
idea of setting dirty_ratio not as a ratio but as an absolute
number of kilobytes as it was suggested by Neil Brown with the
dirty_kb patch a few months back. Would it make sense to forward
port this patch on top of yours ?

cheers
tobi


--
Tobi Oetiker, OETIKER+PARTNER AG, Aarweg 15 CH-4600 Olten
http://it.oetiker.ch tobi@xxxxxxxxxx ++41 62 213 9902

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