From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wr0-f197.google.com (mail-wr0-f197.google.com [209.85.128.197]) by kanga.kvack.org (Postfix) with ESMTP id 049716B0033 for ; Thu, 7 Dec 2017 14:51:06 -0500 (EST) Received: by mail-wr0-f197.google.com with SMTP id y15so4610789wrc.6 for ; Thu, 07 Dec 2017 11:51:05 -0800 (PST) Received: from outbound-smtp22.blacknight.com (outbound-smtp22.blacknight.com. [81.17.249.190]) by mx.google.com with ESMTPS id y89si3523893eda.212.2017.12.07.11.51.04 for (version=TLS1 cipher=AES128-SHA bits=128/128); Thu, 07 Dec 2017 11:51:04 -0800 (PST) Received: from mail.blacknight.com (pemlinmail02.blacknight.ie [81.17.254.11]) by outbound-smtp22.blacknight.com (Postfix) with ESMTPS id 2932FB8C12 for ; Thu, 7 Dec 2017 19:51:04 +0000 (GMT) Date: Thu, 7 Dec 2017 19:51:03 +0000 From: Mel Gorman Subject: Re: [PATCH] mm: page_alloc: avoid excessive IRQ disabled times in free_unref_page_list Message-ID: <20171207195103.dkiqjoeasr35atqj@techsingularity.net> References: <20171207170314.4419-1-l.stach@pengutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <20171207170314.4419-1-l.stach@pengutronix.de> Sender: owner-linux-mm@kvack.org List-ID: To: Lucas Stach Cc: Andrew Morton , Michal Hocko , Vlastimil Babka , linux-mm@kvack.org, kernel@pengutronix.de, patchwork-lst@pengutronix.de On Thu, Dec 07, 2017 at 06:03:14PM +0100, Lucas Stach wrote: > Since 9cca35d42eb6 (mm, page_alloc: enable/disable IRQs once when freeing > a list of pages) we see excessive IRQ disabled times of up to 250ms on an > embedded ARM system (tracing overhead included). > > This is due to graphics buffers being freed back to the system via > release_pages(). Graphics buffers can be huge, so it's not hard to hit > cases where the list of pages to free has 2048 entries. Disabling IRQs > while freeing all those pages is clearly not a good idea. > 250ms to free 2048 entries? That seems excessive but I guess the embedded ARM system is not that fast. > Introduce a batch limit, which allows IRQ servicing once every few pages. > The batch count is the same as used in other parts of the MM subsystem > when dealing with IRQ disabled regions. > > Signed-off-by: Lucas Stach Thanks. Acked-by: Mel Gorman -- 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