From 72cb77f4a5ace37b12dcb47a0e8637a2c28ad881 Mon Sep 17 00:00:00 2001 From: Trond Myklebust Date: Wed, 11 Mar 2009 14:10:30 -0400 Subject: NFS: Throttle page dirtying while we're flushing to disk The following patch is a combination of a patch by myself and Peter Staubach. Trond: If we allow other processes to dirty pages while a process is doing a consistency sync to disk, we can end up never making progress. Peter: Attached is a patch which addresses a continuing problem with the NFS client generating out of order WRITE requests. While this is compliant with all of the current protocol specifications, there are servers in the market which can not handle out of order WRITE requests very well. Also, this may lead to sub-optimal block allocations in the underlying file system on the server. This may cause the read throughputs to be reduced when reading the file from the server. Peter: There has been a lot of work recently done to address out of order issues on a systemic level. However, the NFS client is still susceptible to the problem. Out of order WRITE requests can occur when pdflush is in the middle of writing out pages while the process dirtying the pages calls generic_file_buffered_write which calls generic_perform_write which calls balance_dirty_pages_rate_limited which ends up calling writeback_inodes which ends up calling back into the NFS client to writes out dirty pages for the same file that pdflush happens to be working with. Signed-off-by: Peter Staubach [modification by Trond to merge the two similar patches] Signed-off-by: Trond Myklebust --- fs/nfs/internal.h | 1 + 1 file changed, 1 insertion(+) (limited to 'fs/nfs/internal.h') diff --git a/fs/nfs/internal.h b/fs/nfs/internal.h index 340ede8f608f..a55e69aa52e5 100644 --- a/fs/nfs/internal.h +++ b/fs/nfs/internal.h @@ -165,6 +165,7 @@ extern void nfs_clear_inode(struct inode *); extern void nfs4_clear_inode(struct inode *); #endif void nfs_zap_acl_cache(struct inode *inode); +extern int nfs_wait_bit_killable(void *word); /* super.c */ void nfs_parse_ip_address(char *, size_t, struct sockaddr *, size_t *); -- cgit v1.2.3