Mailinglist Archive: opensuse (1239 mails)

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Re: [opensuse] XFS and openSUSE 12.1
В Mon, 03 Jun 2013 11:14:07 +0200
Roger Oberholtzer <roger@xxxxxx> пишет:

I am using XFS on a 12.1 system. The system records jpeg data to large
files in real time. We have used XFS for this for a while since it has
as a listed feature that it is well suited to writing streaming media
data. We have used this for quite a while on openSUSE 11.2.

We have developed a new version of this system that collects more data.
What I have found is that the jpeg data is typically written at the
speed I expect. Every once in a while, the write takes 100x longer.
Instead of the expected 80 msecs or so to do the compress and write, it
takes, say, 4 or 5 seconds. I have looked in all the usual suspect
places, and nothing seems to point at anything. For one test, I wrote
to /dev/null instead of the real file, The delays do not happen. They do
seem to be related to actually writing to the physical disk.

I expect some delay occasionally when disks are physically flushed.
There is buffering in our application to allow this. But 5 seconds is
simply wrong.


BTW this may explain one possible cause:

http://serverfault.com/questions/126413/limit-linux-background-flush-dirty-pages

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