From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-io0-f176.google.com (mail-io0-f176.google.com [209.85.223.176]) by kanga.kvack.org (Postfix) with ESMTP id 410696B0009 for ; Tue, 2 Feb 2016 11:24:30 -0500 (EST) Received: by mail-io0-f176.google.com with SMTP id g73so22908938ioe.3 for ; Tue, 02 Feb 2016 08:24:30 -0800 (PST) Received: from lgeamrelo13.lge.com (LGEAMRELO13.lge.com. [156.147.23.53]) by mx.google.com with ESMTPS id p9si5580147ioe.174.2016.02.02.08.24.28 for (version=TLS1 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Tue, 02 Feb 2016 08:24:29 -0800 (PST) Date: Wed, 3 Feb 2016 01:24:27 +0900 From: Minchan Kim Subject: Re: [REGRESSION] [BISECTED] kswapd high CPU usage Message-ID: <20160202162427.GA21239@bbox> References: <20160121161656.GA16564@node.shutemov.name> <20160125103853.GD11095@node.shutemov.name> <20160202135950.GA5026@node.shutemov.name> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20160202135950.GA5026@node.shutemov.name> Sender: owner-linux-mm@kvack.org List-ID: To: "Kirill A. Shutemov" Cc: Hugh Greenberg , Andrea Arcangeli , Mel Gorman , Vlastimil Babka , Rik van Riel , Nitin Gupta , Sergey Senozhatsky , linux-mm@kvack.org, Andrew Morton On Tue, Feb 02, 2016 at 03:59:50PM +0200, Kirill A. Shutemov wrote: > On Mon, Jan 25, 2016 at 04:46:58PM +0000, Hugh Greenberg wrote: > > Kirill A. Shutemov shutemov.name> writes: > > > > > > > > On Sat, Jan 23, 2016 at 03:57:21PM +0000, Hugh Greenberg wrote: > > > > Kirill A. Shutemov shutemov.name> writes: > > > > > > > > > > Could you try to insert > > "late_initcall(set_recommended_min_free_kbytes);" > > > > > back and check if makes any difference. > > > > > > > > > > > > > We tested adding late_initcall(set_recommended_min_free_kbytes); > > > > back in 4.1.14 and it made a huge difference. We aren't sure if the > > > > issue is 100% fixed, but it could be. We will keep testing it. > > > > > > It would be nice to have values of min_free_kbytes before and after > > > set_recommended_min_free_kbytes() in your configuration. > > > > > > > Before adding set_recommended_min_free_kbytes: 5391 > > After: 67584 > > [ add more people to the thread ] > > The 'before' value look low to me for machine with 2G of RAM. > > In the bugzilla[1], you've mentioned zram. I wounder if we need to > increase min_free_kbytes when zram is in use as we do for THP. > > [1] https://bugzilla.kernel.org/show_bug.cgi?id=110501 Normally, it's recommended to increate min_free_kbytes when zram is used for swap because zram should allocate a page in reclaim path dynamically to keep compressed page. However, when I read bugzilla's perf profile, I can't find any zram related things and if there is lack of free memory for zram page allocation due to changing min_free_kbytes, user will see below error message. pr_err("Error allocating memory for compressed page: %u, size=%zu\n" -- 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