From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wi0-f175.google.com (mail-wi0-f175.google.com [209.85.212.175]) by kanga.kvack.org (Postfix) with ESMTP id 8B7036B0038 for ; Fri, 7 Aug 2015 03:44:26 -0400 (EDT) Received: by wibhh20 with SMTP id hh20so54503071wib.0 for ; Fri, 07 Aug 2015 00:44:26 -0700 (PDT) Received: from mail-wi0-f182.google.com (mail-wi0-f182.google.com. [209.85.212.182]) by mx.google.com with ESMTPS id z7si9416828wiw.51.2015.08.07.00.44.24 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 07 Aug 2015 00:44:25 -0700 (PDT) Received: by wibxm9 with SMTP id xm9so50823050wib.0 for ; Fri, 07 Aug 2015 00:44:24 -0700 (PDT) Date: Fri, 7 Aug 2015 09:44:22 +0200 From: Michal Hocko Subject: Re: [PATCH 1/1] mm: vmstat: introducing vm counter for slowpath Message-ID: <20150807074422.GE26566@dhcp22.suse.cz> References: <1438931334-25894-1-git-send-email-pintu.k@samsung.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1438931334-25894-1-git-send-email-pintu.k@samsung.com> Sender: owner-linux-mm@kvack.org List-ID: To: Pintu Kumar Cc: akpm@linux-foundation.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, minchan@kernel.org, dave@stgolabs.net, koct9i@gmail.com, mgorman@suse.de, vbabka@suse.cz, js1304@gmail.com, hannes@cmpxchg.org, alexander.h.duyck@redhat.com, sasha.levin@oracle.com, cl@linux.com, fengguang.wu@intel.com, cpgs@samsung.com, pintu_agarwal@yahoo.com, pintu.k@outlook.com, vishnu.ps@samsung.com, rohit.kr@samsung.com On Fri 07-08-15 12:38:54, Pintu Kumar wrote: > This patch add new counter slowpath_entered in /proc/vmstat to > track how many times the system entered into slowpath after > first allocation attempt is failed. This is too lowlevel to be exported in the regular user visible interface IMO. > This is useful to know the rate of allocation success within > the slowpath. What would be that information good for? Is a regular administrator expected to consume this value or this is aimed more to kernel developers? If the later then I think a trace point sounds like a better interface. > This patch is tested on ARM with 512MB RAM. > A sample output is shown below after successful boot-up: > shell> cat /proc/vmstat > nr_free_pages 4712 > pgalloc_normal 1319432 > pgalloc_movable 0 > pageoutrun 379 > allocstall 0 > slowpath_entered 585 > compact_stall 0 > compact_fail 0 > compact_success 0 > > >From the above output we can see that the system entered > slowpath 585 times. > But the existing counter kswapd(pageoutrun), direct_reclaim(allocstall), > direct_compact(compact_stall) does not tell this value. > >From the above value, it clearly indicates that the system have > entered slowpath 585 times. Out of which 379 times allocation passed > through kswapd, without performing direct reclaim/compaction. > That means the remaining 206 times the allocation would have succeeded > using the alloc_pages_high_priority. > > Signed-off-by: Pintu Kumar -- 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