Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751528AbXALCMo (ORCPT ); Thu, 11 Jan 2007 21:12:44 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751532AbXALCMo (ORCPT ); Thu, 11 Jan 2007 21:12:44 -0500 Received: from ug-out-1314.google.com ([66.249.92.172]:32824 "EHLO ug-out-1314.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751519AbXALCMn (ORCPT ); Thu, 11 Jan 2007 21:12:43 -0500 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=beta; h=received:message-id:date:from:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; b=N25i54MLyolghyds+10FObMrT7mQt4V1h96TyZ3YwmJLFMB66w3A2KdeBS+Y8E35zoFN3w55Ik5PjHbnzj90fX3eAlguNs9hSXop7W5e3IF5KUMyARjlf6V34ZpPc4h9v3Lar2KZ5EfzCc8SQe8IvDB4zguai0xXzaRCaeYqkCc= Message-ID: <6d6a94c50701111812q64035fcdheeadfaaf0da9a68c@mail.gmail.com> Date: Fri, 12 Jan 2007 10:12:41 +0800 From: Aubrey To: "Roy Huang" Subject: Re: O_DIRECT question Cc: "Nick Piggin" , "Andrew Morton" , "Linus Torvalds" , "Hua Zhong" , "Hugh Dickins" , linux-kernel@vger.kernel.org, hch@infradead.org, kenneth.w.chen@intel.com, mjt@tls.msk.ru, "Robin Getz" In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <6d6a94c50701101857v2af1e097xde69e592135e54ae@mail.gmail.com> <6d6a94c50701102150w4c3b46d0w6981267e2b873d37@mail.gmail.com> <20070110220603.f3685385.akpm@osdl.org> <6d6a94c50701102245g6afe6aacxfcb2136baee5cbfa@mail.gmail.com> <20070110225720.7a46e702.akpm@osdl.org> <45A5E1B2.2050908@yahoo.com.au> <6d6a94c50701102354l7ab41a3bp4761566204f1d992@mail.gmail.com> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1343 Lines: 30 On 1/11/07, Roy Huang wrote: > On a embedded systerm, limiting page cache can relieve memory > fragmentation. There is a patch against 2.6.19, which limit every > opened file page cache and total pagecache. When the limit reach, it > will release the page cache overrun the limit. The patch seems to work for me. But some suggestions in my mind: 1) Can we limit the total page cache, not the page cache per each file? think about if total memory is 128M, 10% of it is 12.8M, here if one application is running, it can use 12.8M vfs cache, then the performance will probably not be impacted. However, the current patch limit the page cache per each file, which means if only one application runs it can only use CONFIG_PAGE_LIMIT pages cache. It may be small to the application. ------------------snip--------------- if (mapping->nrpages >= mapping->pages_limit) balance_cache(mapping); ------------------snip--------------- 2) A percent number should be better to control the value. Can we add a proc interface to make the value tunable? Thanks, -Aubrey - 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/