From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Mosberger Date: Mon, 13 Mar 2000 18:52:17 +0000 Subject: Re: [Linux-ia64] Q: stack coherency Message-Id: List-Id: References: In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-ia64@vger.kernel.org >>>>> On Sat, 11 Mar 2000 10:02:06 +0100, Manfred Spraul said: Manfred> Can I access a structure that's stored on the stack of one Manfred> CPU from another CPU? IA-64 is no different in this respect from other architectures. If you have an SMP/NUMA/whatever system where the CPUs share the address-space, you will be able to access the stack of another thread (assuming the thread's stack is mapped in the address space). Of course, you also need to have proper synchronization to ensure the stack is still live when the second CPU is trying to access it. I'm not 100% sure what you're asking though, because the "subject" line of your mail asks about stack coherency. Coherency is an orthogonal issue to accessibility. IA-64 uses a weakly ordered memory model to achieve high performance. It's probably best to read the IA-64 architecture manual for the details (see Section 4.4 at http://devresource.hp.com/devresource/Docs/Refs/IA64ISA/), but loosely speaking, memory accesses that happen between a spin-lock/-unlock pair, will be ordered with respect to accesses by other CPUs. --david