From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-lf0-f72.google.com (mail-lf0-f72.google.com [209.85.215.72]) by kanga.kvack.org (Postfix) with ESMTP id EB2FF6B0261 for ; Tue, 18 Oct 2016 05:59:17 -0400 (EDT) Received: by mail-lf0-f72.google.com with SMTP id x79so7946564lff.2 for ; Tue, 18 Oct 2016 02:59:17 -0700 (PDT) Received: from outbound-smtp05.blacknight.com (outbound-smtp05.blacknight.com. [81.17.249.38]) by mx.google.com with ESMTPS id wt1si47782707wjc.140.2016.10.18.02.59.15 for (version=TLS1 cipher=AES128-SHA bits=128/128); Tue, 18 Oct 2016 02:59:15 -0700 (PDT) Received: from mail.blacknight.com (pemlinmail06.blacknight.ie [81.17.255.152]) by outbound-smtp05.blacknight.com (Postfix) with ESMTPS id 5E706986C3 for ; Tue, 18 Oct 2016 09:59:15 +0000 (UTC) Date: Tue, 18 Oct 2016 10:59:12 +0100 From: Mel Gorman Subject: Re: [PATCH] bdi flusher should not be throttled here when it fall into buddy slow path Message-ID: <20161018095912.GD22174@techsingularity.net> References: <1476774765-21130-1-git-send-email-zhouxianrong@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <1476774765-21130-1-git-send-email-zhouxianrong@huawei.com> Sender: owner-linux-mm@kvack.org List-ID: To: zhouxianrong@huawei.com Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, akpm@linux-foundation.org, viro@zeniv.linux.org.uk, mingo@redhat.com, peterz@infradead.org, hannes@cmpxchg.org, vbabka@suse.cz, mhocko@suse.com, vdavydov.dev@gmail.com, minchan@kernel.org, riel@redhat.com, zhouxiyu@huawei.com, zhangshiming5@huawei.com, won.ho.park@huawei.com, tuxiaobing@huawei.com On Tue, Oct 18, 2016 at 03:12:45PM +0800, zhouxianrong@huawei.com wrote: > From: z00281421 > > bdi flusher may enter page alloc slow path due to writepage and kmalloc. > in that case the flusher as a direct reclaimer should not be throttled here > because it can not to reclaim clean file pages or anaonymous pages > for next moment; furthermore writeback rate of dirty pages would be > slow down and other direct reclaimers and kswapd would be affected. > bdi flusher should be iosceduled by get_request rather than here. > > Signed-off-by: z00281421 What does this patch do that PF_LESS_THROTTLE is not doing already if there is an underlying BDI? There have been a few patches like this recently that look like they might do something useful but are subtle. They really should be accompanied by a test case and data showing they either fix a functional issue (machine livelocking due to writeback not making progress) or a performance issue. -- Mel Gorman 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