linux-kernel - [PATCH 3/6] fs: Introduce a per_cpu last

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Message-ID: <492DDC88.2050305@cosmosbay.com>
Date:	Thu, 27 Nov 2008 00:32:24 +0100
From:	Eric Dumazet <dada1@...mosbay.com>
To:	Ingo Molnar <mingo@...e.hu>
CC:	David Miller <davem@...emloft.net>,
	"Rafael J. Wysocki" <rjw@...k.pl>, linux-kernel@...r.kernel.org,
	kernel-testers@...r.kernel.org, Mike Galbraith <efault@....de>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Linux Netdev List <netdev@...r.kernel.org>,
	Christoph Lameter <cl@...ux-foundation.org>,
	Christoph Hellwig <hch@...radead.org>
Subject: [PATCH 3/6] fs: Introduce a per_cpu last_ino allocator

new_inode() dirties a contended cache line to get inode numbers.

Solve this problem by providing to each cpu a per_cpu variable,
feeded by the shared last_ino, but once every 1024 allocations.

This reduce contention on the shared last_ino.

Note : last_ino_get() method must be called with preemption
disabled on SMP.


(socket8 bench result : no differences, but this is because inode_lock
cost is too heavy)

Signed-off-by: Eric Dumazet <dada1@...mosbay.com>
---
 fs/inode.c |   27 +++++++++++++++++++++++++--
 1 files changed, 25 insertions(+), 2 deletions(-)

View attachment "last_ino.patch" of type "text/plain" (1309 bytes)