From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jan Kara Subject: Re: [PATCH 0/2] new APIs to allocate buffer-cache for superblock in non-movable area Date: Mon, 18 Aug 2014 14:11:46 +0200 Message-ID: <20140818121146.GD9603@quack.suse.cz> References: <53EC4531.1000904@lge.com> <20140814142610.6f0d4194c373fef188870772@linux-foundation.org> <20140816185208.GA1589@quack.suse.cz> <53F153B4.1060309@lge.com> <20140818032422.GD23084@thunk.org> <53F184B6.5080503@lge.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: Theodore Ts'o , Jan Kara , Andrew Morton , Alexander Viro , "Paul E. McKenney" , Peter Zijlstra , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, Andreas Dilger , linux-ext4@vger.kernel.org, Minchan Kim , Joonsoo Kim , =?utf-8?B?7J206rG07Zi4?= To: Gioh Kim Return-path: Received: from cantor2.suse.de ([195.135.220.15]:58759 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750709AbaHRMLy (ORCPT ); Mon, 18 Aug 2014 08:11:54 -0400 Content-Disposition: inline In-Reply-To: <53F184B6.5080503@lge.com> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Mon 18-08-14 13:44:38, Gioh Kim wrote: >=20 >=20 > 2014-08-18 =EC=98=A4=ED=9B=84 12:24, Theodore Ts'o =EC=93=B4 =EA=B8=80= : > >On Mon, Aug 18, 2014 at 10:15:32AM +0900, Gioh Kim wrote: > >> > >>My test platform has totally 1GB memory, 256MB for CMA and 768MB fo= r normal. > >>I applied Joonsoo's patch: https://lkml.org/lkml/2014/5/28/64, so t= hat > >>3/4 of allocation take place in normal area and 1/4 allocation take= place in CMA area. > >> > >>And my platform has 4 ext4 partitions. Each ext4 partition has 2 pa= ge caches for superblock that > >>are what this patch tries to move to out of CMA area. > >>Therefore there are 8 page caches (8 pages size) that can prevent p= age migration. > > > >Yes, but are you actually *using* the ext4 partitions for anything? > >If this is a realistic real world use case, file systems are used to > >store, well, files, and that means there will be inodes and dentry > >cache entries that will also be allocated. Does your test scenario > >reflect real world usage? >=20 > Yes. I'm working for LG Electronics. > My test platform is currently selling item in the market. > And also I test my patch when my platform is working as if real user = uses it. Great, this is exactly what I was looking for. So if it really makes your usecase work I don't have objections to your solution (after you change what Andrew suggested). > I think the page caches of the inodes and dentry are held for short t= ime. > I can see pairs of get_bh and put_bh in inodes/dentry handling. >=20 > I think inodes is allocated by kmem_cache_alloc in ext4_alloc_inode()= =2E > It is non-movable area allocation. I guess the hold time depends on what storage do you use in your prod= uct (flash?) and how loaded it is. Honza --=20 Jan Kara SUSE Labs, CR -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" i= n the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html