From mboxrd@z Thu Jan 1 00:00:00 1970 Subject: Re: [PATCH 0/5] make slab gfp fair From: Peter Zijlstra In-Reply-To: References: <20070514131904.440041502@chello.nl> <20070514161224.GC11115@waste.org> <1179164453.2942.26.camel@lappy> <1179170912.2942.37.camel@lappy> <1179250036.7173.7.camel@twins> <1179298771.7173.16.camel@twins> <1179343521.2912.20.camel@lappy> <1179346738.2912.39.camel@lappy> <1179348039.2912.48.camel@lappy> <1179348898.2912.57.camel@lappy> Content-Type: text/plain Date: Wed, 16 May 2007 23:04:54 +0200 Message-Id: <1179349494.2912.62.camel@lappy> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Christoph Lameter Cc: Matt Mackall , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Thomas Graf , David Miller , Andrew Morton , Daniel Phillips , Pekka Enberg List-ID: On Wed, 2007-05-16 at 13:59 -0700, Christoph Lameter wrote: > On Wed, 16 May 2007, Peter Zijlstra wrote: > > > > I do not see any distinction between DMA and regular memory. If we need > > > DMA memory to complete the transaction then this wont work? > > > > If network relies on slabs that are cpuset constrained and the page > > allocator reserves do not match that, then yes, it goes bang. > > So if I put a 32 bit network card in a 64 bit system -> bang? I hope the network stack already uses the appropriate allocator flags. If the slab was GFP_DMA that doesn't change, the ->reserve_slab will still be GFP_DMA. > > > Is there some indicator somewhere that indicates that we are in trouble? I > > > just see the ranks. > > > > Yes, and page->rank will only ever be 0 if the page was allocated with > > ALLOC_NO_WATERMARKS, and that only ever happens if we're in dire > > straights and entitled to it. > > > > Otherwise it'll be ALLOC_WMARK_MIN or somesuch. > > How we know that we are out of trouble? Just try another alloc and see? If > that is the case then we may be failing allocations after the memory > situation has cleared up. No, no, for each regular allocation we retry to populate ->cpu_slab with a new slab. If that works we're out of the woods and the ->reserve_slab is cleaned up. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org