From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail143.messagelabs.com (mail143.messagelabs.com [216.82.254.35]) by kanga.kvack.org (Postfix) with ESMTP id 2900D6B007B for ; Wed, 15 Sep 2010 21:18:35 -0400 (EDT) Received: from d23relay04.au.ibm.com (d23relay04.au.ibm.com [202.81.31.246]) by e23smtp01.au.ibm.com (8.14.4/8.13.1) with ESMTP id o8G1FVAj000821 for ; Thu, 16 Sep 2010 11:15:31 +1000 Received: from d23av02.au.ibm.com (d23av02.au.ibm.com [9.190.235.138]) by d23relay04.au.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id o8G1IRrF2293850 for ; Thu, 16 Sep 2010 11:18:28 +1000 Received: from d23av02.au.ibm.com (loopback [127.0.0.1]) by d23av02.au.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id o8G1IRLj013565 for ; Thu, 16 Sep 2010 11:18:27 +1000 Date: Thu, 16 Sep 2010 10:48:19 +0930 From: Christopher Yeoh Subject: Re: [RFC][PATCH] Cross Memory Attach Message-ID: <20100916104819.36d10acb@lilo> In-Reply-To: References: <20100915104855.41de3ebf@lilo> <4C90A6C7.9050607@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Sender: owner-linux-mm@kvack.org To: Bryan Donlan Cc: Avi Kivity , linux-kernel@vger.kernel.org, Linux Memory Management List , Ingo Molnar List-ID: On Wed, 15 Sep 2010 23:46:09 +0900 Bryan Donlan wrote: > On Wed, Sep 15, 2010 at 19:58, Avi Kivity wrote: >=20 > > Instead of those two syscalls, how about a vmfd(pid_t pid, ulong > > start, ulong len) system call which returns an file descriptor that > > represents a portion of the process address space. =A0You can then > > use preadv() and pwritev() to copy memory, and > > io_submit(IO_CMD_PREADV) and io_submit(IO_CMD_PWRITEV) for > > asynchronous variants (especially useful with a dma engine, since > > that adds latency). > > > > With some care (and use of mmu_notifiers) you can even mmap() your > > vmfd and access remote process memory directly. >=20 > Rather than introducing a new vmfd() API for this, why not just add > implementations for these more efficient operations to the existing > /proc/$pid/mem interface? Perhaps I'm misunderstanding something here, but accessing /proc/$pid/mem requires ptracing the target process. We can't really have all these MPI processes ptraceing each other just to send/receive a message.... Regards, Chris --=20 cyeoh@au.ibm.com -- 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