From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760196AbYE3GWr (ORCPT ); Fri, 30 May 2008 02:22:47 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754337AbYE3GWi (ORCPT ); Fri, 30 May 2008 02:22:38 -0400 Received: from relay2.sgi.com ([192.48.171.30]:36091 "EHLO relay.sgi.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752893AbYE3GWh (ORCPT ); Fri, 30 May 2008 02:22:37 -0400 Date: Thu, 29 May 2008 23:22:31 -0700 (PDT) From: Christoph Lameter X-X-Sender: clameter@schroedinger.engr.sgi.com To: Andrew Morton cc: Eric Dumazet , linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org, David Miller , Peter Zijlstra , Rusty Russell , Mike Travis Subject: Re: [patch 00/41] cpu alloc / cpu ops v3: Optimize per cpu access In-Reply-To: <20080529231618.56e4028b.akpm@linux-foundation.org> Message-ID: References: <20080530035620.587204923@sgi.com> <20080529215827.b659d032.akpm@linux-foundation.org> <20080529222143.5d7aa1e5.akpm@linux-foundation.org> <483F981E.3040004@cosmosbay.com> <20080529231618.56e4028b.akpm@linux-foundation.org> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 29 May 2008, Andrew Morton wrote: > ext3 maintains three percpu_counters per mount. Each percpu_counter > does one percpu_alloc. People can mount an arbitrary number of ext3 > filesystems! But its 4 bytes per alloc right? > Another: there are two percpu_counters (and hence two percpu_alloc()s) > per backing_dev_info. One backing_dev_info per disk and people have > been known to have thousands (iirc ~10,000) disks online. 8 bytes per backing device. 80000 bytes for 10000 disks. > And those examples were plucked only from today's kernel. Who knows > what other problems will be in 2.6.45? We can always increase the sizes.