Re: [PATCH] mm: moving dirty pages balancing to pdfludh entirely

[Nikita Danilov <nikita@clusterfs.com>]

Ananiev, Leonid I writes:
 > Nikita Danilov wtites:
 > >> Pdflush thread functions as before patching. Pdflush tends to make
 > pages
 > >> un-dirty without overload memory or IO and it is not need to let
 > pdflush
 > 
 > > This assumption is valid for ext2
 > 
 > The assumption that pdflush should to make pages un-dirty without
 > overload memory or IO is not for ext2 but for it sense. I'm working with

I am not sure what "sense" is being referred to. Some file systems do
allocate a lot of memory in ->writepages().

ext3 is still in the same ball-park as ext2.

 > ext3. A lot of work it does while writepages(). pdflush is throttled:
 > while vmscan have sorted 32 page for paging-out it calls
 > blk_congestion_wait() nevertheless had it put one of 32 page into
 > congested queue or had not. pdflush is throttled.

pdflush is throttled through blk_congestion_wait(), but it is not
throttled by writing dirty from the tail of inactive list, while
scanning for memory. This destroys LRU ordering.

 > 
 > Leonid
 >  

Nikita.
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