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

JohnS jses27 at gmail.com
Wed Oct 20 09:36:53 EDT 2010


On Tue, 2010-10-19 at 16:34 -0700, Aleksey Tsalolikhin wrote:
> Still seeing the glitch every 5-20 secs after remounting with "commit=6000".
> 
> 
> On Tue, Oct 19, 2010 at 4:00 PM, Ross Walker <rswwalker at gmail.com> wrote:
> >
> > You could also reduce the dirty interval in sysctl so it flushes sooner therefore flushes less data each time.
> 
> OK.  It's worth a shot.  Any idea what the default value is?  I'm not
> sure what value to put in here.
> I know I want to reduce it but I don't want to break my friend's system either.
> 
> http://www.mjmwired.net/kernel/Documentation/sysctl/vm.txt
> 	
> 109	dirty_expire_centisecs
> 110	
> 111	This tunable is used to define when dirty data is old enough to be eligible
> 112	for writeout by the pdflush daemons.  It is expressed in 100'ths
> of a second.
> 113	Data which has been dirty in-memory for longer than this interval will be
> 114	written out next time a pdflush daemon wakes up.
> 
----
Maybe add in this also vm.dirty_ratio = 50  Start at 0 and work your way
up.

John



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