Jeff: This brings up an interesting issue with the RDMA transport and RDMA_READ. RDMA_READ is submitted as part of fetching an RPC from the client (e.g. NFS_WRITE). The xpo_recvfrom function doesn't block waiting for the RDMA_READ to complete, but rather queues the RPC for subsequent processing when the I/O completes and returns 0. I can use these new services to allocate CPU local pages for this I/O. So far, so good. However, when the I/O completes, and the transport is rescheduled for subsequent RPC completion processing, the pool/CPU that is elected doesn't have any affinity for the CPU on which the I/O was initially submitted. I think this means that the svc_process/reply steps may occur on a CPU far away from the memory in which the data resides. Am I making sense here? If so, any thoughts on what could/should be done? Thanks, Tom On Tue, 2008-06-03 at 07:16 -0400, Jeff Layton wrote: > The sunrpc code has had some support for spreading pooled services over > different NUMA nodes and CPUs for some time. So far though, this support > has been for CPU masks only. Memory allocated for these services is > generally done by whatever CPU happens to be running the init script > that starts the services and so most of it ends up on the same NUMA node. > This means that nfsd's end up wasting a lot of time updating remote > memory on a different memory node. > > This patchset attempts to remedy that by having pooled services make > per-thread allocations that are on their local memory node. I have no > hard performance numbers for this particular patchset, but Greg Banks > sent me a different patch that has a similar effect and claims that > there is a significant performance gain. > > Comments and suggestions appreciated... > > Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx> > -- > To unsubscribe from this list: send the line "unsubscribe linux-nfs" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
