From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753078AbcBJTLa (ORCPT ); Wed, 10 Feb 2016 14:11:30 -0500 Received: from alln-iport-7.cisco.com ([173.37.142.94]:2340 "EHLO alln-iport-7.cisco.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752245AbcBJTL2 (ORCPT ); Wed, 10 Feb 2016 14:11:28 -0500 X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: =?us-ascii?q?A0D2AQCRirtW/5JdJa1egzpSbYhcsSIBD?= =?us-ascii?q?YFmIYVsAoE5OBQBAQEBAQEBgQqEQgEBBDhBEAsYCQwZD0gGAQwIAQGIFw7AWgE?= =?us-ascii?q?BAQEBAQEBAQEBAQEBAQEBAQEBAREEC4YHgXWCQoRxg3sBBI4biF2FTIgFiSKFU?= =?us-ascii?q?o4/HgEBQoQFSYhTAQEB?= X-IronPort-AV: E=Sophos;i="5.22,426,1449532800"; d="scan'208";a="237024820" Subject: Re: computing drop-able caches To: Dave Hansen , "Khalid Mughal (khalidm)" , Rik van Riel , Johannes Weiner References: <56AAA77D.7090000@cisco.com> <20160128235815.GA5953@cmpxchg.org> <56AABA79.3030103@cisco.com> <56AAC085.9060509@cisco.com> <20160129015534.GA6401@cmpxchg.org> <56ABEAA7.1020706@redhat.com> <56BB7BC7.4040403@cisco.com> <56BB7DDE.8080206@intel.com> Cc: Alexander Viro , Michal Hocko , Andrew Morton , "linux-fsdevel@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "linux-mm@kvack.org" , "xe-kernel@external.cisco.com" From: Daniel Walker Message-ID: <56BB8B5E.0@cisco.com> Date: Wed, 10 Feb 2016 11:11:26 -0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.5.1 MIME-Version: 1.0 In-Reply-To: <56BB7DDE.8080206@intel.com> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit X-Auto-Response-Suppress: DR, OOF, AutoReply Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 02/10/2016 10:13 AM, Dave Hansen wrote: > On 02/10/2016 10:04 AM, Daniel Walker wrote: >>> [Linux_0:/]$ echo 3 > /proc/sys/vm/drop_caches >>> [Linux_0:/]$ cat /proc/meminfo >>> MemTotal: 3977836 kB >>> MemFree: 1095012 kB >>> MemAvailable: 1434148 kB >> I suspect MemAvailable takes into account more than just the droppable >> caches. For instance, reclaimable slab is included, but I don't think >> drop_caches drops that part. > There's a bit for page cache and a bit for slab, see: > > https://kernel.org/doc/Documentation/sysctl/vm.txt > > Ok, then this looks like a defect then. I would think MemAvailable would always be smaller then MemFree (after echo 3 > /proc/sys/vm/drop_caches).. Unless there is something else be accounted for that we aren't aware of. Daniel