Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754076Ab2EKAZe (ORCPT ); Thu, 10 May 2012 20:25:34 -0400 Received: from LGEMRELSE6Q.lge.com ([156.147.1.121]:54884 "EHLO LGEMRELSE6Q.lge.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751681Ab2EKAZd (ORCPT ); Thu, 10 May 2012 20:25:33 -0400 X-AuditID: 9c930179-b7bb9ae000000ea5-27-4fac5c7a962c Message-ID: <4FAC5C87.3060504@kernel.org> Date: Fri, 11 May 2012 09:25:43 +0900 From: Minchan Kim User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:11.0) Gecko/20120410 Thunderbird/11.0.1 MIME-Version: 1.0 Newsgroups: gmane.linux.kernel.mm,gmane.linux.kernel To: Dan Magenheimer CC: Nitin Gupta , Pekka Enberg , Greg Kroah-Hartman , Seth Jennings , Andrew Morton , linux-kernel@vger.kernel.org, linux-mm@kvack.org, cl@linux-foundation.org Subject: Re: [PATCH 4/4] zsmalloc: zsmalloc: align cache line size References: <1336027242-372-1-git-send-email-minchan@kernel.org> <1336027242-372-4-git-send-email-minchan@kernel.org> <4FA28EFD.5070002@vflare.org> <4FA33E89.6080206@kernel.org> <4FA7C2BC.2090400@vflare.org> <4FA87837.3050208@kernel.org> <731b6638-8c8c-4381-a00f-4ecd5a0e91ae@default> <4FA9C127.5020908@kernel.org> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-Brightmail-Tracker: AAAAAA== Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3075 Lines: 91 On 05/11/2012 09:03 AM, Dan Magenheimer wrote: >> From: Minchan Kim [mailto:minchan@kernel.org] >> Subject: Re: [PATCH 4/4] zsmalloc: zsmalloc: align cache line size >> >> On 05/08/2012 11:00 PM, Dan Magenheimer wrote: >> >>>> From: Minchan Kim [mailto:minchan@kernel.org] >>>>> zcache can potentially create a lot of pools, so the latter will save >>>>> some memory. >>>> >>>> >>>> Dumb question. >>>> Why should we create pool per user? >>>> What's the problem if there is only one pool in system? >>> >>> zcache doesn't use zsmalloc for cleancache pages today, but >>> that's Seth's plan for the future. Then if there is a >>> separate pool for each cleancache pool, when a filesystem >>> is umount'ed, it isn't necessary to walk through and delete >>> all pages one-by-one, which could take quite awhile. >> >>> >> >>> ramster needs one pool for each client (i.e. machine in the >>> cluster) for frontswap pages for the same reason, and >>> later, for cleancache pages, one per mounted filesystem >>> per client >> >> >> Fair enough. >> But some subsystems can't want a own pool for not waste unnecessary memory. >> >> Then, how about this interfaces like slab? >> >> 1. zs_handle zs_malloc(size_t size, gfp_t flags) - share a pool by many subsystem(like kmalloc) >> 2. zs_handle zs_malloc_pool(struct zs_pool *pool, size_t size) - use own pool(like kmem_cache_alloc) >> >> Any thoughts? > > I don't have any objections to adding this kind of > capability to zsmalloc. But since we are just speculating > that this capability would be used by some future > kernel subsystem, isn't it normal kernel protocol for > this new capability NOT to be added until that future > kernel subsystem creates a need for it. Now zram makes pool per block device and a embedded system may use zram for several block device, ex) swap device, several compressed tmpfs In such case, share pool is better than private pool because embedded system don't mount/umount frequently on such directories since booting. > > As I said in reply to the other thread, there is missing > functionality in zsmalloc that is making it difficult for > it to be used by zcache. It would be good if Seth > and Nitin (and any other kernel developers) would work So, if you guys post TODO list, it helps fix the direction. > on those issues before adding capabilities for non-existent > future users of zsmalloc. I think it's not urgent than zs_handle mess. > > Again, that's just my opinion. > Dan > > -- > 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/ . > Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ > Don't email: email@kvack.org > -- Kind regards, Minchan Kim -- 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/