Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759359Ab3FMVuU (ORCPT ); Thu, 13 Jun 2013 17:50:20 -0400 Received: from mail-qc0-f172.google.com ([209.85.216.172]:63247 "EHLO mail-qc0-f172.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759274Ab3FMVuQ (ORCPT ); Thu, 13 Jun 2013 17:50:16 -0400 Date: Thu, 13 Jun 2013 14:50:09 -0700 From: Tejun Heo To: Kent Overstreet Cc: Andrew Morton , linux-kernel@vger.kernel.org, Oleg Nesterov , Christoph Lameter , Ingo Molnar , Andi Kleen , Jens Axboe , "Nicholas A. Bellinger" , "Rafael J. Wysocki" Subject: Re: [PATCH] Percpu tag allocator Message-ID: <20130613215009.GF13970@mtj.dyndns.org> References: <1371009804-11596-1-git-send-email-koverstreet@google.com> <20130612163854.91da28042ab7a943b69a5970@linux-foundation.org> <20130613190610.GA13970@mtj.dyndns.org> <20130613121324.2cab80256217df97254af16c@linux-foundation.org> <20130613192152.GC13970@mtj.dyndns.org> <20130613211425.GC8650@moria.home.lan> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20130613211425.GC8650@moria.home.lan> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1121 Lines: 27 (cc'ing Rafael and Oleg) On Thu, Jun 13, 2013 at 02:14:25PM -0700, Kent Overstreet wrote: > Yeah, I think you're definitely right. (I only started reading up on the > freezer stuff yesterday, though). > > Do you know offhand what existing (i.e. slab) allocators do? Whatever > they do should make sense for us. I don't think the memory allocator does anything. Memory allocations are guaranteed to make forward progress and everything should still be working while freezing, so it doesn't need to do anything special. If the tag allocator is to be used only by kernel proper - say drivers, block layer, it shouldn't need to do anything special. If it's directly exposed to userland via something like aio and the userland is involved in guaranteeing forward progress - ie. freeing of tags - then the allocator would need to be able to fail, I think. Thanks. -- tejun -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/