Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751658AbWE0Pyt (ORCPT ); Sat, 27 May 2006 11:54:49 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751598AbWE0Pw0 (ORCPT ); Sat, 27 May 2006 11:52:26 -0400 Received: from smtp.ustc.edu.cn ([202.38.64.16]:39388 "HELO ustc.edu.cn") by vger.kernel.org with SMTP id S1751600AbWE0Pvg (ORCPT ); Sat, 27 May 2006 11:51:36 -0400 Message-ID: <348745093.16246@ustc.edu.cn> X-EYOUMAIL-SMTPAUTH: wfg@mail.ustc.edu.cn Message-Id: <20060527155134.715578802@localhost.localdomain> References: <20060527154849.927021763@localhost.localdomain> Date: Sat, 27 May 2006 23:49:07 +0800 From: Wu Fengguang To: Andrew Morton Cc: linux-kernel@vger.kernel.org, Wu Fengguang Subject: [PATCH 18/32] readahead: initial method - thrashing guard size Content-Disposition: inline; filename=readahead-method-initial-size-thrash.patch Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1851 Lines: 53 backing_dev_info.ra_thrash_bytes is dynamicly updated to be a little above the thrashing safe read-ahead size. It is used in the initial method where the thrashing threshold for the particular reader is still unknown. Signed-off-by: Wu Fengguang --- mm/readahead.c | 20 ++++++++++++++++++++ 1 files changed, 20 insertions(+) --- linux-2.6.17-rc4-mm3.orig/mm/readahead.c +++ linux-2.6.17-rc4-mm3/mm/readahead.c @@ -796,6 +796,22 @@ out: } /* + * Update `backing_dev_info.ra_thrash_bytes' to be a _biased_ average of + * read-ahead sizes. Which makes it an a-bit-risky(*) estimation of the + * _minimal_ read-ahead thrashing threshold on the device. + * + * (*) Note that being a bit risky can _help_ overall performance. + */ +static inline void update_ra_thrash_bytes(struct backing_dev_info *bdi, + unsigned long ra_size) +{ + ra_size <<= PAGE_CACHE_SHIFT; + bdi->ra_thrash_bytes = (bdi->ra_thrash_bytes < ra_size) ? + (ra_size + bdi->ra_thrash_bytes * 1023) / 1024: + (ra_size + bdi->ra_thrash_bytes * 7) / 8; +} + +/* * The node's accumulated aging activities. */ static unsigned long node_readahead_aging(void) @@ -1144,6 +1160,10 @@ state_based_readahead(struct address_spa if (!adjust_rala(growth_limit, &ra_size, &la_size)) return 0; + /* ra_size in its _steady_ state reflects thrashing threshold */ + if (page && ra_old + ra_old / 8 >= ra_size) + update_ra_thrash_bytes(mapping->backing_dev_info, ra_size); + ra_set_class(ra, RA_CLASS_STATE); ra_set_index(ra, index, ra->readahead_index); ra_set_size(ra, ra_size, la_size); -- - 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/