From: Ted Ts'o Subject: Re: [PATCH 2/2] percpu_counter: Put a reasonable upper bound on percpu_counter_batch Date: Mon, 29 Aug 2011 09:27:34 -0400 Message-ID: <20110829132734.GB12187@thunk.org> References: <20110826072622.406d3395@kryten> <20110826072927.5b4781f9@kryten> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: adilger.kernel@dilger.ca, eric.dumazet@gmail.com, tj@kernel.org, linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org To: Anton Blanchard Return-path: Received: from li9-11.members.linode.com ([67.18.176.11]:54529 "EHLO test.thunk.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753524Ab1H2N1v (ORCPT ); Mon, 29 Aug 2011 09:27:51 -0400 Content-Disposition: inline In-Reply-To: Sender: linux-ext4-owner@vger.kernel.org List-ID: On Fri, Aug 26, 2011 at 07:48:52AM -0400, Theodore Tso wrote: > > I understand why we would want to reduce this number. Unfortunately, the > question is what do we do if all 1024 threads try to do buffered writes into > the file system at the same instant, when we have less than 4 megabytes > of space left? Oops, sorry, that should be 4 GB of space left (i.e., what do we do if all 1024 cpu's all try write 1024 4k blocks all at the same time). Imagine an simulation application where all threads finish at more or less the same time and then try to write out their data files at the same time.... - Ted