From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Dumazet Subject: [PATCH] vfs: avoid call to inode_lru_list_del() if possible Date: Thu, 28 Jul 2011 06:55:13 +0200 Message-ID: <1311828913.2697.33.camel@edumazet-laptop> References: <1311294452.2576.18.camel@schen9-DESK> <20110723132411.GA22183@infradead.org> <1311633550.2576.33.camel@schen9-DESK> <20110725225154.GD22133@ZenIV.linux.org.uk> <1311636178.2576.34.camel@schen9-DESK> <1311660013.2996.6.camel@edumazet-laptop> <1311668466.2355.12.camel@edumazet-HP-Compaq-6005-Pro-SFF-PC> <20110726090357.GA13013@infradead.org> <1311672994.2355.17.camel@edumazet-HP-Compaq-6005-Pro-SFF-PC> <1311780065.2356.18.camel@edumazet-HP-Compaq-6005-Pro-SFF-PC> <20110727204415.GA13308@infradead.org> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: Tim Chen , Al Viro , David Miller , Andi Kleen , Matthew Wilcox , Anton Blanchard , npiggin@kernel.dk, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, netdev To: Christoph Hellwig Return-path: In-Reply-To: <20110727204415.GA13308@infradead.org> Sender: linux-fsdevel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org Le mercredi 27 juillet 2011 =C3=A0 16:44 -0400, Christoph Hellwig a =C3= =A9crit : > 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 s= pots. > >=20 > > After following patch, a close(socket(PF_INET, SOCK_DGRAM, 0)) pair= on > > my dev machine takes ~3us instead of ~9us. > >=20 > > Maybe its better to split it in three patches, just let me know. >=20 > I think three patches would be a lot cleaner. >=20 > As for safety of the unlocked checks: >=20 > - 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()= =2E >=20 > Btw, I wonder if you should micro-optimize things a bit further by > moving the unhashed checks from the deletion functions into the calle= rs > and thus save a function call for each of them. >=20 Here is the last patch, addressing inode_lru_list_del() call. Only the call done from iput_final() can obviously benefit from checkin= g 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 --- 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) } =20 inode->i_state |=3D I_FREEING; - inode_lru_list_del(inode); + if (!list_empty(&inode->i_lru)) + inode_lru_list_del(inode); spin_unlock(&inode->i_lock); =20 evict(inode); -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel= " in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html