From mboxrd@z Thu Jan 1 00:00:00 1970 From: Nick Piggin Subject: Re: [13/18] x86_64: Allow fallback for the stack Date: Tue, 9 Oct 2007 18:46:22 +1000 References: <20071004035935.042951211@sgi.com> <200710082255.05598.nickpiggin@yahoo.com.au> In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200710091846.22796.nickpiggin@yahoo.com.au> Sender: owner-linux-mm@kvack.org Return-Path: To: Christoph Lameter Cc: Rik van Riel , Andi Kleen , akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, travis@sgi.com List-ID: On Wednesday 10 October 2007 04:39, Christoph Lameter wrote: > On Mon, 8 Oct 2007, Nick Piggin wrote: > > The tight memory restrictions on stack usage do not come about because > > of the difficulty in increasing the stack size :) It is because we want > > to keep stack sizes small! > > > > Increasing the stack size 4K uses another 4MB of memory for every 1000 > > threads you have, right? > > > > It would take a lot of good reason to move away from the general > > direction we've been taking over the past years that 4/8K stacks are a > > good idea for regular 32 and 64 bit builds in general. > > We already use 32k stacks on IA64. So the memory argument fail there. I'm talking about generic code. > > > I have some concerns about the medium NUMA systems (a few dozen of > > > nodes) also running out of stack since more data is placed on the stack > > > through the policy layer and since we may end up with a couple of > > > stacked filesystems. Most of the current NUMA systems on x86_64 are > > > basically two nodes on one motherboard. The use of NUMA controls is > > > likely limited there and the complexity of the filesystems is also not > > > high. > > > > The solution has until now always been to fix the problems so they don't > > use so much stack. Maybe a bigger stack is OK for you for 1024+ CPU > > systems, but I don't think you'd be able to make that assumption for most > > normal systems. > > Yes that is why I made the stack size configurable. Fine. I just don't see why you need this fallback. -- 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