On Thu, 2019-01-03 at 17:49 -0500, Chuck Lever wrote: > > On Jan 3, 2019, at 4:35 PM, Chuck Lever <chuck.lever@xxxxxxxxxx> > > wrote: > > > > > On Jan 3, 2019, at 4:28 PM, Trond Myklebust < > > > trondmy@xxxxxxxxxxxxxxx> wrote: > > > > > > On Thu, 2019-01-03 at 16:07 -0500, Chuck Lever wrote: > > > > > On Jan 3, 2019, at 3:53 PM, Chuck Lever < > > > > > chuck.lever@xxxxxxxxxx> > > > > > wrote: > > > > > > > > > > > On Jan 3, 2019, at 1:47 PM, Trond Myklebust < > > > > > > trondmy@xxxxxxxxxxxxxxx> wrote: > > > > > > > > > > > > On Thu, 2019-01-03 at 13:29 -0500, Chuck Lever wrote: > > > > > > > + reclen = req->rq_snd_buf.len; > > > > > > > + marker = cpu_to_be32(RPC_LAST_STREAM_FRAGMENT | > > > > > > > reclen); > > > > > > > + return kernel_sendmsg(transport->sock, &msg, &iov, 1, > > > > > > > iov.iov_len); > > > > > > > > > > > > So what does this do for performance? I'd expect that > > > > > > adding > > > > > > another > > > > > > dive into the socket layer will come with penalties. > > > > > > > > > > NFSv3 on TCP, sec=sys, 56Gbs IBoIP, v4.20 + my v4.21 patches > > > > > fio, 8KB random, 70% read, 30% write, 16 threads, iodepth=16 > > > > > > > > > > Without this patch: > > > > > > > > > > read: IOPS=28.7k, BW=224MiB/s (235MB/s)(11.2GiB/51092msec) > > > > > write: IOPS=12.3k, BW=96.3MiB/s (101MB/s)(4918MiB/51092msec) > > > > > > > > > > With this patch: > > > > > > > > > > read: IOPS=28.6k, BW=224MiB/s (235MB/s)(11.2GiB/51276msec) > > > > > write: IOPS=12.3k, BW=95.8MiB/s (100MB/s)(4914MiB/51276msec) > > > > > > > > > > Seems like that's in the noise. > > > > > > > > Sigh. That's because it was the same kernel. Again, with > > > > feeling: > > > > > > > > 4.20.0-rc7-00048-g9274254: > > > > read: IOPS=28.6k, BW=224MiB/s (235MB/s)(11.2GiB/51276msec) > > > > write: IOPS=12.3k, BW=95.8MiB/s (100MB/s)(4914MiB/51276msec) > > > > > > > > 4.20.0-rc7-00049-ga4dea15: > > > > read: IOPS=27.2k, BW=212MiB/s (223MB/s)(11.2GiB/53979msec) > > > > write: IOPS=11.7k, BW=91.1MiB/s (95.5MB/s)(4917MiB/53979msec) > > > > > > > > > > So about a 5% reduction in performance? > > > > On this workload, yes. > > > > Could send the record marker in xs_send_kvec with the head[0] > > iovec. > > I'm going to try that next. > > That helps: > > Linux 4.20.0-rc7-00049-g664f679 #651 SMP Thu Jan 3 17:35:26 EST 2019 > > read: IOPS=28.7k, BW=224MiB/s (235MB/s)(11.2GiB/51185msec) > write: IOPS=12.3k, BW=96.1MiB/s (101MB/s)(4919MiB/51185msec) > Interesting... Perhaps we might be able to eke out a few more percent performance on file writes by also converting xs_send_pagedata() to use a single sock_sendmsg() w/ iov_iter rather than looping through several calls to sendpage()? -- Trond Myklebust Linux NFS client maintainer, Hammerspace trond.myklebust@xxxxxxxxxxxxxxx
