From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wi0-f182.google.com (mail-wi0-f182.google.com [209.85.212.182]) by kanga.kvack.org (Postfix) with ESMTP id 67AB66B0038 for ; Thu, 17 Sep 2015 11:13:31 -0400 (EDT) Received: by wicfx3 with SMTP id fx3so28386977wic.1 for ; Thu, 17 Sep 2015 08:13:30 -0700 (PDT) Received: from mail-wi0-f170.google.com (mail-wi0-f170.google.com. [209.85.212.170]) by mx.google.com with ESMTPS id w4si4707236wju.16.2015.09.17.08.13.29 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 17 Sep 2015 08:13:30 -0700 (PDT) Received: by wiclk2 with SMTP id lk2so31808421wic.1 for ; Thu, 17 Sep 2015 08:13:29 -0700 (PDT) Date: Thu, 17 Sep 2015 18:13:28 +0300 From: "Kirill A. Shutemov" Subject: Re: [RFC v5 3/3] mm: make swapin readahead to improve thp collapse rate Message-ID: <20150917151327.GA31549@node.dhcp.inet.fi> References: <1442259105-4420-1-git-send-email-ebru.akagunduz@gmail.com> <1442259105-4420-4-git-send-email-ebru.akagunduz@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <1442259105-4420-4-git-send-email-ebru.akagunduz@gmail.com> Sender: owner-linux-mm@kvack.org List-ID: To: Ebru Akagunduz Cc: linux-mm@kvack.org, akpm@linux-foundation.org, kirill.shutemov@linux.intel.com, n-horiguchi@ah.jp.nec.com, aarcange@redhat.com, riel@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 On Mon, Sep 14, 2015 at 10:31:45PM +0300, 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 > 400B 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 %65 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 > Acked-by: Rik van Riel [ resend with correct TO/CC lists]