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| author | Eric Dumazet <dada1@cosmosbay.com> | 2005-09-06 15:18:16 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@g5.osdl.org> | 2005-09-07 16:57:41 -0700 |
| commit | 3f4bb1f4199b7dc0c958447b1e4898980013b884 (patch) | |
| tree | 3d8aacfc6b7bbf7b2d224ae10ca693c55c64739e /fs/buffer.c | |
| parent | 0811bab24ff1eecab38110eda7ea7847db95c64e (diff) | |
| download | lwn-3f4bb1f4199b7dc0c958447b1e4898980013b884.tar.gz lwn-3f4bb1f4199b7dc0c958447b1e4898980013b884.zip | |
[PATCH] struct dentry: place d_hash close to d_parent and d_name to speedup lookups
dentry cache uses sophisticated RCU technology (and prefetching if
available) but touches 2 cache lines per dentry during hlist lookup.
This patch moves d_hash in the same cache line than d_parent and d_name
fields so that :
1) One cache line is needed instead of two.
2) the hlist_for_each_rcu() prefetching has a chance to bring all the
needed data in advance, not only the part that includes d_hash.next.
I also changed one old comment that was wrong for 64bits.
A further optimisation would be to separate dentry in two parts, one that
is mostly read, and one writen (d_count/d_lock) to avoid false sharing on
SMP/NUMA but this would need different field placement depending on 32bits
or 64bits platform.
Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'fs/buffer.c')
0 files changed, 0 insertions, 0 deletions