Messages in this thread | | | Date | Tue, 16 Sep 2008 15:07:29 -0400 | From | Chris Snook <> | Subject | Re: How to find out, what "pdflush" is working on |
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Martin Knoblauch wrote: > Hi, > > I find the following comment in mm/pdflush.c > > /* * The pdflush threads are worker threads for writing back dirty data. * > Ideally, we'd like one thread per active disk spindle. But the disk * > topology is very hard to divine at this level. Instead, we take * care in > various places to prevent more than one pdflush thread from * performing > writeback against a single filesystem. pdflush threads * have the PF_FLUSHER > flag set in current->flags to aid in this. */ > > Is there a way to find out what a certain instance of "pdflush" is working > on? Like which block-device or which fliesystem it is writing to? I am still > (2.6.27) trying to track down why writing a single file can make linux very > sluggish and unresponsive. If that happens I usually see all possible 8 > "pdflush" threads being in "D"-state. According to above comment only one of > them should be really busy.
The key word is "ideally". We'd like it to work that way, but it doesn't. Patches to fix this are welcome.
-- Chris
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