From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx107.postini.com [74.125.245.107]) by kanga.kvack.org (Postfix) with SMTP id 75C7A6B0012 for ; Fri, 15 Feb 2013 06:04:07 -0500 (EST) Date: Fri, 15 Feb 2013 12:04:04 +0100 From: Michal Hocko Subject: Re: [PATCH] mm: fadvise: Drain all pagevecs if POSIX_FADV_DONTNEED fails to discard all pages Message-ID: <20130215110401.GA31037@dhcp22.suse.cz> References: <20130214120349.GD7367@suse.de> <20130214123926.599fcef8.akpm@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20130214123926.599fcef8.akpm@linux-foundation.org> Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton Cc: Mel Gorman , Rob van der Heij , Hugh Dickins , Linux-MM , LKML On Thu 14-02-13 12:39:26, Andrew Morton wrote: > On Thu, 14 Feb 2013 12:03:49 +0000 > Mel Gorman wrote: > > > Rob van der Heij reported the following (paraphrased) on private mail. > > > > The scenario is that I want to avoid backups to fill up the page > > cache and purge stuff that is more likely to be used again (this is > > with s390x Linux on z/VM, so I don't give it as much memory that > > we don't care anymore). So I have something with LD_PRELOAD that > > intercepts the close() call (from tar, in this case) and issues > > a posix_fadvise() just before closing the file. > > > > This mostly works, except for small files (less than 14 pages) > > that remains in page cache after the face. > > Sigh. We've had the "my backups swamp pagecache" thing for 15 years > and it's still happening. > > It should be possible nowadays to toss your backup application into a > container to constrain its pagecache usage. So we can type > > run-in-a-memcg -m 200MB /my/backup/program > > and voila. Does such a script exist and work? The script would be as simple as: cgcreate -g memory:backups/`whoami` cgset -r memory.limit_in_bytes=200MB backups/`whoami` cgexec -g memory:backups/`whoami` /my/backup/program It just expects that admin sets up backups group which allows the user to create a subgroup (w permission on the directory) and probably set up some reasonable cap for all backups [...] -- Michal Hocko SUSE Labs -- 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