From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Lameter Subject: Re: [15/17] SLUB: Support virtual fallback via SLAB_VFALLBACK Date: Mon, 1 Oct 2007 13:55:29 -0700 (PDT) Message-ID: References: <20070919033605.785839297@sgi.com> <20070919033643.763818012@sgi.com> <200709280742.38262.nickpiggin@yahoo.com.au> <1191002119.18147.80.camel@lappy> <1191003950.18147.85.camel@lappy> <20070929011311.8b51dedb.akpm@linux-foundation.org> <1191055632.18147.101.camel@lappy> <20070929020049.f73f4aea.akpm@linux-foundation.org> Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Cc: Peter Zijlstra , Nick Piggin , Christoph Hellwig , Mel Gorman , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, David Chinner , Jens Axboe To: Andrew Morton Return-path: Received: from netops-testserver-3-out.sgi.com ([192.48.171.28]:60996 "EHLO relay.sgi.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1755147AbXJAUza (ORCPT ); Mon, 1 Oct 2007 16:55:30 -0400 In-Reply-To: <20070929020049.f73f4aea.akpm@linux-foundation.org> Sender: linux-fsdevel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org On Sat, 29 Sep 2007, Andrew Morton wrote: > > atomic allocations. And with SLUB using higher order pages, atomic !0 > > order allocations will be very very common. > > Oh OK. > > I thought we'd already fixed slub so that it didn't do that. Maybe that > fix is in -mm but I don't think so. > > Trying to do atomic order-1 allocations on behalf of arbitray slab caches > just won't fly - this is a significant degradation in kernel reliability, > as you've very easily demonstrated. Ummm... SLAB also does order 1 allocations. We have always done them. See mm/slab.c /* * Do not go above this order unless 0 objects fit into the slab. */ #define BREAK_GFP_ORDER_HI 1 #define BREAK_GFP_ORDER_LO 0 static int slab_break_gfp_order = BREAK_GFP_ORDER_LO;