NFS: avoid waiting at all in nfs_release_page when congested.
If nfs_release_page() is called on a sequence of pages which are all in the same file which is blocked on COMMIT, each page could contribute a 1 second delay which could be come excessive. I have seen delays of as much as 208 seconds. To keep the delay to one second, mark the bdi as write-congested if the commit didn't finished. Once it does finish, the write-congested flag will be cleared by nfs_commit_release_pages(). With this, the longest total delay in try_to_free_pages that I have seen is under 3 seconds. With no waiting in nfs_release_page at all I have seen delays of nearly 1.5 seconds. Signed-off-by:NeilBrown <neilb@suse.de> Acked-by:
Jeff Layton <jlayton@primarydata.com> Signed-off-by:
Trond Myklebust <trond.myklebust@primarydata.com>
parent
95905446
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