On Sun, Apr 28, 2013 at 7:42 AM, J. Bruce Fields <bfields@xxxxxxxxxxxx> wrote: >> On Wed, Apr 17, 2013 at 7:36 AM, Yan Burman >> When running ib_send_bw, I get 4.3-4.5 GB/sec for block sizes 4-512K. >> When I run fio over rdma mounted nfs, I get 260-2200MB/sec for the > > same block sizes (4-512K). running over IPoIB-CM, I get 200-980MB/sec. > ... [snip] >> 36.18% nfsd [kernel.kallsyms] [k] mutex_spin_on_owner > > That's the inode i_mutex. > >> 14.70%-- svc_send > > That's the xpt_mutex (ensuring rpc replies aren't interleaved). > >> >> 9.63% nfsd [kernel.kallsyms] [k] _raw_spin_lock_irqsave >> > > And that (and __free_iova below) looks like iova_rbtree_lock. > > Let's revisit your command: "FIO arguments: --rw=randread --bs=4k --numjobs=2 --iodepth=128 --ioengine=libaio --size=100000k --prioclass=1 --prio=0 --cpumask=255 --loops=25 --direct=1 --invalidate=1 --fsync_on_close=1 --randrepeat=1 --norandommap --group_reporting --exitall --buffered=0" * inode's i_mutex: If increasing process/file count didn't help, maybe increase "iodepth" (say 512 ?) could offset the i_mutex overhead a little bit ? * xpt_mutex: (no idea) * iova_rbtree_lock DMA mapping fragmentation ? I have not studied whether NFS-RDMA routines such as "svc_rdma_sendto()" could do better but maybe sequential IO (instead of "randread") could help ? Bigger block size (instead of 4K) can help ? -- Wendy -- 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
