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Date: Wed, 27 Jul 2011 19:12:12 +0200
From: Andi Kleen <andi@firstfloor.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>,
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        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
Message-ID: <20110727171212.GZ8006@one.firstfloor.org>
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>
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> Before even taking locks, we can perform an unlocked test to check if
> inode can possibly be in the lists.
> 
> On a 2x4x2 machine, a close(socket()) pair can be 200% faster with these
> changes.

Great result! Seems simple and obvious to me.

-Andi