Mailinglist Archive: opensuse (1239 mails)

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Re: [opensuse] Re: XFS and openSUSE 12.1
  • From: Roger Oberholtzer <roger@xxxxxx>
  • Date: Wed, 12 Jun 2013 12:23:36 +0200
  • Message-id: <1371032616.16366.4.camel@acme.pacific>
On Wed, 2013-06-12 at 12:33 +0300, auxsvr@xxxxxxxxx wrote:
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?

Seems to be 100 MB/s in our rests. The app is generating 25 MB/sec.

I will check what values I have for this. They are whatever is the
installed default. My cache use goes way above 20%. It gets to 50 or 60%
of RAM.



Yours sincerely,

Roger Oberholtzer

Ramböll RST / Systems

Office: Int +46 10-615 60 20
Mobile: Int +46 70-815 1696
roger.oberholtzer@xxxxxxxxxx
________________________________________

Ramböll Sverige AB
Krukmakargatan 21
P.O. Box 17009
SE-104 62 Stockholm, Sweden
www.rambollrst.se


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