[CentOS] pdflush kernel thread pops up every 10 seconds or so and video decoding grinds to a halt for 1/2 a second

Aleksey Tsalolikhin atsaloli.tech at gmail.com
Tue Oct 19 15:34:21 EDT 2010


On Mon, Oct 18, 2010 at 9:08 PM, JohnS <jses27 at gmail.com> wrote:
>
> On Mon, 2010-10-18 at 18:25 -0700, Aleksey Tsalolikhin wrote:
>> Hi. A friend of mine was doing real-time video decoding on
>> Fedora Core 13 and he had a performance glitch (1/2 a second
>> freeze) every 5-10 seconds.  "top" showed flush-253:0
>> process at the moment of the freeze.
>
> And what is the Priority of it running at?  How many Cores also?

He sees this issue at normal priority and at nice -n -19 / -20.

He has 6 cores with hyperthreading on

3.8 Ghz, the memory is 1.850 Mhz

The system is 980x Intel 6 core

He just told me he has two modes for his decoding program, in one
mode the system does not write to disk at all, and there are NO GLITCHES
doing it this way; another way, it writes lots of little files as it decodes,
and the glitch happens actually every 5-20 seconds.

Would like to get to the bottom of this so he can decode with temp files
and without glitches.

Cheers,
Aleksey


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