Messages in this thread | | | Date | Tue, 29 Sep 2009 10:00:07 -0400 | From | Chris Mason <> | Subject | Re: regression in page writeback |
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On Tue, Sep 29, 2009 at 10:32:27AM +0800, Wu Fengguang wrote: > On Mon, Sep 28, 2009 at 09:08:04PM +0800, Christoph Hellwig wrote: > > On Mon, Sep 28, 2009 at 03:15:07PM +0800, Wu Fengguang wrote: > > > + if (!PageActive(page)) > > > + SetPageReclaim(page); > > > + err = mapping->a_ops->writepage(page, wbc); > > > + if (err < 0) > > > + handle_write_error(mapping, page, res); > > > + if (err == AOP_WRITEPAGE_ACTIVATE) { > > > + ClearPageReclaim(page); > > > + res = PAGE_ACTIVATE; > > > + break; > > > + } > > > > This should help a bit for XFS as it historically does multi-page > > writeouts from ->writepages (and apprently btrfs that added some > > ->writepage ? > > > write-around recently?) but not those brave filesystems only > > implementing the multi-page writeout from writepages as designed. > > Thanks. Just tried write_cache_pages(), looks simple. Need to further > convert all aops->writepages to support lumpy pageout :) > > > But really, the best would be to leave the writeout to the flusher > > threads and just reclaim the clean pages from the VM. > > Yup, that's much larger behavior change, and could be pursued as a > long term goal.
I don't think we can just change kswapd to wait on flusher thread progress because the flusher thread can happily spend forever writing pages that can't actually be freed. Lumpy pageout is a better middle ground I think.
-chris
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