Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753740AbaGDIiY (ORCPT ); Fri, 4 Jul 2014 04:38:24 -0400 Received: from odin2.bull.net ([129.184.85.11]:54545 "EHLO odin2.bull.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751128AbaGDIiW (ORCPT ); Fri, 4 Jul 2014 04:38:22 -0400 Message-ID: <53B667F9.90306@bull.net> Date: Fri, 4 Jul 2014 10:38:17 +0200 From: Sebastien Buisson User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.5.0 MIME-Version: 1.0 To: , , , Andrew Morton Subject: [PATCH] Allow increasing the buffer-head per-CPU LRU size Content-Type: text/plain; charset="ISO-8859-1"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [10.192.1.123] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Allow increasing the buffer-head per-CPU LRU size to allow efficient filesystem operations that access many blocks for each transaction. For example, creating a file in a large ext4 directory with quota enabled will accesses multiple buffer heads and will overflow the LRU at the default 8-block LRU size: * parent directory inode table block (ctime, nlinks for subdirs) * new inode bitmap * inode table block * 2 quota blocks * directory leaf block (not reused, but pollutes one cache entry) * 2 levels htree blocks (only one is reused, other pollutes cache) * 2 levels indirect/index blocks (only one is reused) The buffer-head per-CPU LRU size can be changed at config time, and its default value is raised to 16. Signed-off-by: Liang Zhen Signed-off-by: Andreas Dilger --- fs/Kconfig | 9 +++++++++ fs/buffer.c | 3 +-- 2 files changed, 10 insertions(+), 2 deletions(-) diff --git a/fs/Kconfig b/fs/Kconfig index c229f82..afea808 100644 --- a/fs/Kconfig +++ b/fs/Kconfig @@ -268,4 +268,13 @@ endif # NETWORK_FILESYSTEMS source "fs/nls/Kconfig" source "fs/dlm/Kconfig" +config BH_LRU_SIZE + int "buffer head per-CPU LRU size" + range 8 64 + default "16" + help + This sets the per-CPU LRU size for buffer heads in memory. + More complex filesystems may be modiyfing multiple blocks + within a single transaction, so keeping the buffer heads in + CPU-local cache speeds up modifations significantly. endmenu diff --git a/fs/buffer.c b/fs/buffer.c index 6024877..b83fa63 100644 --- a/fs/buffer.c +++ b/fs/buffer.c @@ -1255,8 +1255,7 @@ static struct buffer_head *__bread_slow(struct buffer_head *bh) * The LRUs themselves only need locking against invalidate_bh_lrus. We use * a local interrupt disable for that. */ - -#define BH_LRU_SIZE 8 +#define BH_LRU_SIZE CONFIG_BH_LRU_SIZE struct bh_lru { struct buffer_head *bhs[BH_LRU_SIZE]; -- 1.7.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/