On Tue, Mar 31, 2015 at 07:21:16AM -0700, lyndat3@xxxxxxxxxxxxx wrote: > Narrowing doen the issue, NFSv4 file xfer with 'sync' appears, here, to be ~ 300X slower than with 'async'. > > (1) for NFSv4 mount with 'sync' > > grep NAS1 /etc/auto.nfs4 > NAS1 -fstype=nfs4,_netdev,rw,proto=tcp,sync,... xen01.loc:/ > > a 100MB file xfer takes ~8 minutes > > rm -f /mnt/NFS4/NAS1/file.out && \ > time dd if=/dev/zero of=/mnt/NFS4/NAS1/file.out bs=32K count=3K > 3072+0 records in > 3072+0 records out > 100663296 bytes (101 MB) copied, 485.721 s, 207 kB/s > > real 8m5.861s > user 0m0.012s > sys 0m0.250s > > (2) Change mount 'sync' -> 'async', > > vi /etc/auto.nfs4 > - NAS1 -fstype=nfs4,_netdev,rw,proto=tcp,sync,... xen01.loc:/ > + NAS1 -fstype=nfs4,_netdev,rw,proto=tcp,async,... xen01.loc:/ > systemctl restart autofs > > the same 100MB file xfer takes ~ 2 seconds > > rm -f /mnt/NFS4/NAS1/file.out && \ > time dd if=/dev/zero of=/mnt/NFS4/NAS1/file.out bs=32K count=3K > 3072+0 records in > 3072+0 records out > 100663296 bytes (101 MB) copied, 1.65577 s, 60.8 MB/s > > real 0m1.658s > user 0m0.000s > sys 0m0.089s > > > I'd expect 'sync' to be slower than 'async', but 300X ? There's no maximum sync/async ratio. You could make that ratio lower or higher by varying dd's block size, for example. The way I'd look at it, your dd of a 100MB file above is doing 3072 writes, and taking about 8*60/3072 =~ .16 seconds per write. That does sound high. Things to look at to understand why might include the round-trip ping time to the server, and the time for the server's disk to do a synchronous write. --b. > > Is there additional config that cures, or at least drastically improves, this slow down? > > Some very old (10+ years) posts suggested kernel bugs, but those were fixed ages ago. Maybe reemerged? > > LT > -- > 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
