From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail143.messagelabs.com (mail143.messagelabs.com [216.82.254.35]) by kanga.kvack.org (Postfix) with ESMTP id 06F926B002D for ; Thu, 10 Nov 2011 05:50:02 -0500 (EST) Date: Thu, 10 Nov 2011 10:51:00 +0000 From: Alan Cox Subject: Re: [PATCH] mm: Do not stall in synchronous compaction for THP allocations Message-ID: <20111110105100.23fa78f9@lxorguk.ukuu.org.uk> In-Reply-To: <20111110100616.GD3083@suse.de> References: <20111110100616.GD3083@suse.de> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Mel Gorman Cc: Andrew Morton , Jan Kara , Andy Isaacson , Johannes Weiner , Andrea Arcangeli , linux-kernel@vger.kernel.org, linux-mm@kvack.org On Thu, 10 Nov 2011 10:06:16 +0000 Mel Gorman wrote: > Occasionally during large file copies to slow storage, there are still > reports of user-visible stalls when THP is enabled. Reports on this > have been intermittent and not reliable to reproduce locally but; If you want to cause a massive stall take a cheap 32GB USB flash drive plug it into an 8GB box and rsync a lot of small files to it. 400,000 emails in maildir format does the trick and can easily be simulated. The drive drops to about 1-2 IOPS with all the small mucking around and the backlog becomes massive. > Internally in SUSE, I received a bug report related to stalls in firefox > when using Java and Flash heavily while copying from NFS > to VFAT on USB. It has not been confirmed to be the same problem > but if it looks like a duck and quacks like a duck..... With the 32GB USB flash rsync I see firefox block for up to 45 minutes although operating entirely on an unrelated filesystem. I suspect it may be a problem that is visible because an fsync is getting jammed up in the mess. Alan -- 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org