Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754255AbbFOOAI (ORCPT ); Mon, 15 Jun 2015 10:00:08 -0400 Received: from mx1.redhat.com ([209.132.183.28]:44138 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754161AbbFON75 (ORCPT ); Mon, 15 Jun 2015 09:59:57 -0400 Message-ID: <557EDA53.3040906@redhat.com> Date: Mon, 15 Jun 2015 09:59:47 -0400 From: Rik van Riel User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.4.0 MIME-Version: 1.0 To: Ebru Akagunduz , linux-mm@kvack.org CC: akpm@linux-foundation.org, kirill.shutemov@linux.intel.com, n-horiguchi@ah.jp.nec.com, aarcange@redhat.com, iamjoonsoo.kim@lge.com, xiexiuqi@huawei.com, gorcunov@openvz.org, linux-kernel@vger.kernel.org, mgorman@suse.de, rientjes@google.com, vbabka@suse.cz, aneesh.kumar@linux.vnet.ibm.com, hughd@google.com, hannes@cmpxchg.org, mhocko@suse.cz, boaz@plexistor.com, raindel@mellanox.com Subject: Re: [RFC 3/3] mm: make swapin readahead to improve thp collapse rate References: <1434294283-8699-1-git-send-email-ebru.akagunduz@gmail.com> <1434294283-8699-4-git-send-email-ebru.akagunduz@gmail.com> In-Reply-To: <1434294283-8699-4-git-send-email-ebru.akagunduz@gmail.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1218 Lines: 34 On 06/14/2015 11:04 AM, Ebru Akagunduz wrote: > This patch makes swapin readahead to improve thp collapse rate. > When khugepaged scanned pages, there can be a few of the pages > in swap area. > > With the patch THP can collapse 4kB pages into a THP when > there are up to max_ptes_swap swap ptes in a 2MB range. > > The patch was tested with a test program that allocates > 800MB of memory, writes to it, and then sleeps. I force > the system to swap out all. Afterwards, the test program > touches the area by writing, it skips a page in each > 20 pages of the area. > > Without the patch, system did not swap in readahead. > THP rate was %47 of the program of the memory, it > did not change over time. > > With this patch, after 10 minutes of waiting khugepaged had > collapsed %99 of the program's memory. > > Signed-off-by: Ebru Akagunduz Mechanism looks good to me. Acked-by: Rik van Riel -- All rights reversed -- 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/