> 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) -- Chuck Lever
