Le mercredi 27 juillet 2011 à 16:44 -0400, Christoph Hellwig a écrit : > On Wed, Jul 27, 2011 at 05:21:05PM +0200, Eric Dumazet wrote: > > If I am not mistaken, we can add unlocked checks on the three hot spots. > > > > After following patch, a close(socket(PF_INET, SOCK_DGRAM, 0)) pair on > > my dev machine takes ~3us instead of ~9us. > > > > Maybe its better to split it in three patches, just let me know. > > I think three patches would be a lot cleaner. > > As for safety of the unlocked checks: > > - inode are either hashed when created or never, so that one looks > fine. > - same for the sb list. > - the writeback list is a bit more dynamic as we move things around > quite a bit. But in additon to the inode_wb_list_del call from > evict() it only ever gets remove in writeback_single_inode, which > for a freeing inode can only be called from the callers of evict(). > > Btw, I wonder if you should micro-optimize things a bit further by > moving the unhashed checks from the deletion functions into the callers > and thus save a function call for each of them. > Here is the last patch, addressing inode_lru_list_del() call. Only the call done from iput_final() can obviously benefit from checking i_lru being empty or not, so it makes sense to perform the check at caller site instead of doing it in inode_lru_list_del() [PATCH] vfs: avoid call to inode_lru_list_del() if possible inode_lru_list_del() is expensive because of per superblock lru locking, while some inodes are not in lru list. Adding a check in iput_final() can speedup pipe/sockets workloads on SMP. Signed-off-by: Eric Dumazet <eric.dumazet@xxxxxxxxx> --- fs/inode.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/fs/inode.c b/fs/inode.c index d0c72ff..b8b8939 100644 --- a/fs/inode.c +++ b/fs/inode.c @@ -1328,7 +1328,8 @@ static void iput_final(struct inode *inode) } inode->i_state |= I_FREEING; - inode_lru_list_del(inode); + if (!list_empty(&inode->i_lru)) + inode_lru_list_del(inode); spin_unlock(&inode->i_lock); evict(inode); -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
