From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <47B2765A.2070901@myri.com> Date: Tue, 12 Feb 2008 23:47:22 -0500 From: Patrick Geoffray MIME-Version: 1.0 Subject: Re: [ofa-general] Re: Demand paging for memory regions References: <20080209075556.63062452@bree.surriel.com> <47B2174E.5000708@opengridcomputing.com> <20080213032533.GC32047@obsidianresearch.com> <47B26A6A.4000209@myri.com> <20080213042600.GA32449@obsidianresearch.com> In-Reply-To: <20080213042600.GA32449@obsidianresearch.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Jason Gunthorpe Cc: Christoph Lameter , Roland Dreier , linux-kernel@vger.kernel.org, linux-mm@kvack.org, general@lists.openfabrics.org List-ID: Jason Gunthorpe wrote: > [mangled CC list trimmed] Thanks, noticed that afterwards. > This wasn't ment as a slight against Quadrics, only to point out that > the specific wire protcols used by IB and iwarp are what cause this > limitation, it would be easy to imagine that Quadrics has some > additional twist that can make this easier.. The wire protocols are similar, nothing fancy. The specificity of Quadrics (and many others) is that they can change the behavior of the NIC in firmware, so they adapt to what the OS offers. They had the VM notifier support in Tru64 back in the days, they just ported the functionality to Linux. > I ment that HPC users are unlikely to want to swap active RDMA pages > if this causes a performance cost on normal operations. None of my Swapping to disk is not a normal operations in HPC, it's going to be slow anyway. The main problem for HPC users is not swapping, it's that they do not know when a registered page is released to the OS through free(), sbrk() or munmap(). Like swapping, they don't expect that it will happen often, but they have to handle it gracefully. Patrick -- Patrick Geoffray Myricom, Inc. http://www.myri.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