From: Christoph Hellwig <hch@infradead.org>
To: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Christoph Hellwig <hch@infradead.org>,
Tim Chen <tim.c.chen@linux.intel.com>,
Al Viro <viro@ZenIV.linux.org.uk>,
David Miller <davem@davemloft.net>,
Andi Kleen <andi@firstfloor.org>, Matthew Wilcox <matthew@wil.cx>,
Anton Blanchard <anton@samba.org>,
npiggin@kernel.dk, linux-kernel@vger.kernel.org,
linux-fsdevel@vger.kernel.org, netdev <netdev@vger.kernel.org>
Subject: Re: [PATCH] vfs: avoid taking locks if inode not in lists
Date: Wed, 27 Jul 2011 16:44:15 -0400 [thread overview]
Message-ID: <20110727204415.GA13308@infradead.org> (raw)
In-Reply-To: <1311780065.2356.18.camel@edumazet-HP-Compaq-6005-Pro-SFF-PC>
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.
next prev parent reply other threads:[~2011-07-27 20:44 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20110717010427.GC5359@parisc-linux.org>
[not found] ` <20110717084630.GC8006@one.firstfloor.org>
[not found] ` <1310977028.5756.1.camel@edumazet-HP-Compaq-6005-Pro-SFF-PC>
[not found] ` <20110718154008.GA29593@infradead.org>
[not found] ` <20110718155141.GA11013@ZenIV.linux.org.uk>
[not found] ` <1311093158.2707.75.camel@schen9-DESK>
[not found] ` <20110721204042.GB31405@ZenIV.linux.org.uk>
[not found] ` <1311294452.2576.18.camel@schen9-DESK>
[not found] ` <20110723132411.GA22183@infradead.org>
[not found] ` <1311633550.2576.33.camel@schen9-DESK>
[not found] ` <20110725225154.GD22133@ZenIV.linux.org.uk>
[not found] ` <1311636178.2576.34.camel@schen9-DESK>
[not found] ` <1311660013.2996.6.camel@edumazet-laptop>
2011-07-26 8:21 ` [PATCH] vfs: dont chain pipe/anon/socket on superblock s_inodes list Eric Dumazet
2011-07-26 9:03 ` Christoph Hellwig
2011-07-26 9:36 ` Eric Dumazet
2011-07-26 9:42 ` Christoph Hellwig
2011-07-26 10:43 ` Eric Dumazet
2011-07-26 11:49 ` Christoph Hellwig
2011-07-27 15:21 ` [PATCH] vfs: avoid taking locks if inode not in lists Eric Dumazet
2011-07-27 17:12 ` Andi Kleen
2011-07-27 20:44 ` Christoph Hellwig [this message]
2011-07-27 20:59 ` Andi Kleen
2011-07-27 21:01 ` Christoph Hellwig
2011-07-28 4:11 ` [PATCH] vfs: conditionally call inode_wb_list_del() Eric Dumazet
2011-07-28 4:41 ` [PATCH] vfs: avoid taking locks if inode not in lists Eric Dumazet
2011-07-28 4:55 ` [PATCH] vfs: avoid call to inode_lru_list_del() if possible Eric Dumazet
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