From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail137.messagelabs.com (mail137.messagelabs.com [216.82.249.19]) by kanga.kvack.org (Postfix) with SMTP id 6E93A6B02A4 for ; Tue, 20 Jul 2010 19:03:11 -0400 (EDT) Received: by iwn2 with SMTP id 2so7320856iwn.14 for ; Tue, 20 Jul 2010 16:03:09 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <1279283870-18549-5-git-send-email-ngupta@vflare.org> References: <1279283870-18549-1-git-send-email-ngupta@vflare.org> <1279283870-18549-5-git-send-email-ngupta@vflare.org> Date: Wed, 21 Jul 2010 08:03:09 +0900 Message-ID: Subject: Re: [PATCH 4/8] Shrink zcache based on memlimit From: Minchan Kim Content-Type: text/plain; charset=ISO-8859-1 Sender: owner-linux-mm@kvack.org To: Nitin Gupta Cc: Pekka Enberg , Hugh Dickins , Andrew Morton , Greg KH , Dan Magenheimer , Rik van Riel , Avi Kivity , Christoph Hellwig , Konrad Rzeszutek Wilk , linux-mm , linux-kernel List-ID: Hi, On Fri, Jul 16, 2010 at 9:37 PM, Nitin Gupta wrote: > User can change (per-pool) memlimit using sysfs node: > /sys/kernel/mm/zcache/pool/memlimit > > When memlimit is set to a value smaller than current > number of pages allocated for that pool, excess pages > are now freed immediately instead of waiting for get/ > flush for these pages. > > Currently, victim page selection is essentially random. > Automatic cache resizing and better page replacement > policies will be implemented later. Okay. I know this isn't end. I just want to give a concern before you end up. I don't know how you implement reclaim policy. In current implementation, you use memlimit for determining when reclaim happen. But i think we also should follow global reclaim policy of VM. I means although memlimit doen't meet, we should reclaim zcache if system has a trouble to reclaim memory. AFAIK, cleancache doesn't give any hint for that. so we should implement it in zcache itself. At first glance, we can use shrink_slab or oom_notifier. But both doesn't give any information of zone although global reclaim do it by per-zone. AFAIK, Nick try to implement zone-aware shrink slab. Also if we need it, we can change oom_notifier with zone-aware oom_notifier. Now it seems anyone doesn't use oom_notifier so I am not sure it's useful. It's just my opinion. Thanks for effort for good feature. Nitin. -- Kind regards, Minchan Kim -- 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