From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f72.google.com (mail-wm0-f72.google.com [74.125.82.72]) by kanga.kvack.org (Postfix) with ESMTP id BA7086B0038 for ; Tue, 25 Apr 2017 17:44:05 -0400 (EDT) Received: by mail-wm0-f72.google.com with SMTP id u5so7739558wmg.13 for ; Tue, 25 Apr 2017 14:44:05 -0700 (PDT) Received: from gum.cmpxchg.org (gum.cmpxchg.org. [85.214.110.215]) by mx.google.com with ESMTPS id p23si1185550edc.0.2017.04.25.14.44.04 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 25 Apr 2017 14:44:04 -0700 (PDT) Date: Tue, 25 Apr 2017 17:43:57 -0400 From: Johannes Weiner Subject: Re: [PATCH -mm -v10 2/3] mm, THP, swap: Check whether THP can be split firstly Message-ID: <20170425214357.GA6841@cmpxchg.org> References: <20170425125658.28684-1-ying.huang@intel.com> <20170425125658.28684-3-ying.huang@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170425125658.28684-3-ying.huang@intel.com> Sender: owner-linux-mm@kvack.org List-ID: To: "Huang, Ying" Cc: Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org On Tue, Apr 25, 2017 at 08:56:57PM +0800, Huang, Ying wrote: > From: Huang Ying > > To swap out THP (Transparent Huage Page), before splitting the THP, > the swap cluster will be allocated and the THP will be added into the > swap cache. But it is possible that the THP cannot be split, so that > we must delete the THP from the swap cache and free the swap cluster. > To avoid that, in this patch, whether the THP can be split is checked > firstly. The check can only be done racy, but it is good enough for > most cases. > > With the patch, the swap out throughput improves 3.6% (from about > 4.16GB/s to about 4.31GB/s) in the vm-scalability swap-w-seq test case > with 8 processes. The test is done on a Xeon E5 v3 system. The swap > device used is a RAM simulated PMEM (persistent memory) device. To > test the sequential swapping out, the test case creates 8 processes, > which sequentially allocate and write to the anonymous pages until the > RAM and part of the swap device is used up. > > Cc: Johannes Weiner > Signed-off-by: "Huang, Ying" > Acked-by: Kirill A. Shutemov [for can_split_huge_page()] Acked-by: Johannes Weiner -- 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