Re: [PATCH 5/6] writeback: try more writeback as long as something was written

Christoph Hellwig
2011-04-21T04:39:46Z

On Thu, Apr 21, 2011 at 11:33:25AM +0800, Wu Fengguang wrote:
> I collected the writeback_single_inode() traces (patch attached for
> your reference) each for several test runs, and find much more
> I_DIRTY_PAGES after patchset. Dave, do you know why there are so many
> I_DIRTY_PAGES (or radix tag) remained after the XFS ->writepages() call,
> even for small files?

What is your defintion of a small file? As soon as it has multiple
extents or holes there's absolutely no way to clean it with a single
writepage call. Also XFS tries to operate as non-blocking as possible
if the non-blocking flag is set in the wbc, but that flag actually
seems to be dead these days.