[mangled CC list trimmed] On Tue, Feb 12, 2008 at 10:56:26PM -0500, Patrick Geoffray wrote:
> Jason Gunthorpe wrote: >> I don't know much about Quadrics, but I would be hesitant to lump it >> in too much with these RDMA semantics. Christian's comments sound like >> they operate closer to what you described and that is why the have an >> existing patch set. I don't know :) > > The Quadrics folks have been doing RDMA for 10 years, there is a reason why > they maintained a patch. 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.. >> What it boils down to is that to implement true removal of pages in a >> general way the kernel and HCA must either drop packets or stall >> incoming packets, both are big performance problems - and I can't see >> many users wanting this. Enterprise style people using SCSI, NFS, etc >> already have short pin periods and HPC MPI users probably won't care >> about the VM issues enough to warrent the performance overhead. > > This is not true, HPC people do care about the VM issues a lot. Memory > registration (pinning and translating) is usually too expensive to 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 comments are ment to imply that lazy de-registration or page migration are not good things. Regards, Jason -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/