Messages in this thread Patch in this message | | | Date | Thu, 03 Mar 2011 14:45:15 +0800 | From | Wu Fengguang <> | Subject | [PATCH 10/27] nfs: limit the commit size to reduce fluctuations |
| |
Limit the commit size to 1/8 dirty control scope, so that the arrival of one commit will not knock the overall dirty pages off the scope.
CC: Trond Myklebust <Trond.Myklebust@netapp.com> Signed-off-by: Wu Fengguang <fengguang.wu@intel.com> --- fs/nfs/write.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)
After patch, there are still drop offs from the control scope,
http://www.kernel.org/pub/linux/kernel/people/wfg/writeback/dirty-throttling-v6/NFS/nfs-1dd-1M-8p-2945M-20%25-2.6.38-rc6-dt6+-2011-02-22-21-09/balance_dirty_pages-pages.png
due to bursty arrival of commits:
http://www.kernel.org/pub/linux/kernel/people/wfg/writeback/dirty-throttling-v6/NFS/nfs-1dd-1M-8p-2945M-20%25-2.6.38-rc6-dt6+-2011-02-22-21-09/nfs-commit.png
--- linux-next.orig/fs/nfs/write.c 2011-03-02 20:39:01.000000000 +0800 +++ linux-next/fs/nfs/write.c 2011-03-02 20:39:01.000000000 +0800 @@ -1492,9 +1492,10 @@ static int nfs_commit_unstable_pages(str if (wbc->sync_mode == WB_SYNC_NONE) { /* Don't commit yet if this is a non-blocking flush and there - * are a lot of outstanding writes for this mapping. + * are a lot of outstanding writes for this mapping, until + * collected enough pages to commit. */ - if (nfsi->ncommit <= (nfsi->npages >> 1)) + if (nfsi->ncommit <= nfsi->npages / 32 /* DIRTY_MARGIN */) goto out_mark_dirty; /* don't wait for the COMMIT response */
| |