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authorMeelap Shah <meelap@umich.edu>2007-07-17 04:04:39 -0700
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-07-17 10:23:07 -0700
commitc2f1a551dea8b37c2e0cb886885c250fb703e9d8 (patch)
tree11a5f256703d856017ceb2268bd02b7b510dee30 /include/linux
parent1e5140279f31e47d58ed6036ee61ba7a65710e63 (diff)
downloadop-kernel-dev-c2f1a551dea8b37c2e0cb886885c250fb703e9d8.zip
op-kernel-dev-c2f1a551dea8b37c2e0cb886885c250fb703e9d8.tar.gz
knfsd: nfsd4: vary maximum delegation limit based on RAM size
Our original NFSv4 delegation policy was to give out a read delegation on any open when it was possible to. Since the lifetime of a delegation isn't limited to that of an open, a client may quite reasonably hang on to a delegation as long as it has the inode cached. This becomes an obvious problem the first time a client's inode cache approaches the size of the server's total memory. Our first quick solution was to add a hard-coded limit. This patch makes a mild incremental improvement by varying that limit according to the server's total memory size, allowing at most 4 delegations per megabyte of RAM. My quick back-of-the-envelope calculation finds that in the worst case (where every delegation is for a different inode), a delegation could take about 1.5K, which would make the worst case usage about 6% of memory. The new limit works out to be about the same as the old on a 1-gig server. [akpm@linux-foundation.org: Don't needlessly bloat vmlinux] [akpm@linux-foundation.org: Make it right for highmem machines] Signed-off-by: "J. Bruce Fields" <bfields@citi.umich.edu> Signed-off-by: Neil Brown <neilb@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include/linux')
-rw-r--r--include/linux/nfsd/nfsd.h1
1 files changed, 1 insertions, 0 deletions
diff --git a/include/linux/nfsd/nfsd.h b/include/linux/nfsd/nfsd.h
index 0d84204..ce5e345 100644
--- a/include/linux/nfsd/nfsd.h
+++ b/include/linux/nfsd/nfsd.h
@@ -148,6 +148,7 @@ extern int nfsd_max_blksize;
* NFSv4 State
*/
#ifdef CONFIG_NFSD_V4
+extern unsigned int max_delegations;
void nfs4_state_init(void);
int nfs4_state_start(void);
void nfs4_state_shutdown(void);
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