Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759293Ab3FMV5t (ORCPT ); Thu, 13 Jun 2013 17:57:49 -0400 Received: from mail-pd0-f174.google.com ([209.85.192.174]:50313 "EHLO mail-pd0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755049Ab3FMV5s (ORCPT ); Thu, 13 Jun 2013 17:57:48 -0400 Date: Thu, 13 Jun 2013 14:58:00 -0700 From: Kent Overstreet To: Tejun Heo 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: <20130613215800.GB28664@moria.home.lan> 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> <20130613215009.GF13970@mtj.dyndns.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20130613215009.GF13970@mtj.dyndns.org> 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: 1312 Lines: 26 On Thu, Jun 13, 2013 at 02:50:09PM -0700, Tejun Heo wrote: > (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. That's a good point - as long as whatever is allocated is guaranteed to be freed in bounded time, we should be fine. -- 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/