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

[Nikita Danilov <nikita@clusterfs.com>]

Ananiev, Leonid I writes:
 > Nikita Danilov writes:
 > > Some people do, should they suffer? :-)
 > You - yes. You have used that example as an argument incorrectly.

You are inhumane. :-) What is incorrect in assuming people may have many
devices?

 > 
 > > Not _all_, only nr_to_write of them
 > 	Yes. User thread writes all dirty pages in the system calling

No. User thread will not write _all_ dirty pages (if it does---it's a
bug in the current code and should be fixed):

balance_dirty_pages():
			if (pages_written >= write_chunk)
				break;		/* We've done our duty */

writeback_inodes():
		if (wbc->nr_to_write <= 0)
			break;

sync_sb_inodes():
		if (wbc->nr_to_write <= 0)
			break;

mpage_writepages():
			if (ret || (--(wbc->nr_to_write) <= 0))
				done = 1;

Everywhere down call-chain ->nr_to_write is checked.

 > writeback_inodes() and after it tests
 > 			if (pages_written >= write_chunk)

[rants skipped.]

 > 
 > Leonid

Nikita.