From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail202.messagelabs.com (mail202.messagelabs.com [216.82.254.227]) by kanga.kvack.org (Postfix) with SMTP id A56196B0047 for ; Mon, 22 Feb 2010 21:25:40 -0500 (EST) Date: Tue, 23 Feb 2010 13:25:27 +1100 From: Dave Chinner Subject: Re: [PATCH v2] Make VM_MAX_READAHEAD a kernel parameter Message-ID: <20100223022527.GB22370@discord.disaster> References: <201002091659.27037.knikanth@suse.de> <201002111715.04411.knikanth@suse.de> <20100214213724.GA28392@discord.disaster> <201002151006.37294.knikanth@suse.de> <20100221142600.GA10036@localhost> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20100221142600.GA10036@localhost> Sender: owner-linux-mm@kvack.org To: Wu Fengguang Cc: Nikanth Karthikesan , Ankit Jain , Andrew Morton , "balbir@linux.vnet.ibm.com" , Jens Axboe , "linux-kernel@vger.kernel.org" , "linux-mm@kvack.org" , Christian Ehrhardt List-ID: On Sun, Feb 21, 2010 at 10:26:00PM +0800, Wu Fengguang wrote: > Nikanth, > > > > > + readahead= Default readahead value for block devices. > > > > + > > > > > > I think the description should define the units (kb) and valid value > > > ranges e.g. page size to something not excessive - say 65536kb. The > > > above description is, IMO, useless without refering to the source to > > > find out this information.... > > > > > > > The parameter can be specified with/without any suffix(k/m/g) that memparse() > > helper function can accept. So it can take 1M, 1024k, 1050620. I checked other > > parameters that use memparse() to get similar values and they didn't document > > it. May be this should be described here. > > Hope this helps clarify things to user: > > + readahead=nn[KM] > + Default max readahead size for block devices. > + Range: 0; 4k - 128m Yes, that is exactly what I was thinA,ing of. Thanks. Cheers, Dave. -- Dave Chinner david@fromorbit.com -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org