Mailinglist Archive: opensuse (1239 mails)

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Re: [opensuse] Re: XFS and openSUSE 12.1
On Tuesday 11 of June 2013 14:52:36 Roger Oberholtzer wrote:
In my strange use, I have only one single writer per disk, no reader. No
files are deleted. Just one growing file (up to 2GB) on a pristine disk.

As a little test, I made a 60 second loop that runs the following each
iteration:

echo 1 > /proc/sys/vm/drop_caches

This results in the cache going away. More interestingly, it seems that
this also results in even write times. There are small variations, which
I expect. But I have yet to see the longer ones. There is no discernible
delay when the command is run. Just less memory given over to cache, and
(fingers crossed) less periodic housekeeping as a result.

Have you tried reducing the maximum size of dirty data before they are written
to disk? See https://www.kernel.org/doc/Documentation/sysctl/vm.txt ,
http://serverfault.com/questions/126413/limit-linux-background-flush-dirty-pages,
in particular /proc/sys/vm/dirty_ratio or dirty_bytes. On my system,
dirty_ratio is at 20%, which is too high for a system with 32GB of RAM.

What is the throughput of your disks?

Yours sincerely,

Roger Oberholtzer

Regards,
Peter

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