Consistently interrupted playback

[DBMandrake]

@THEM

@popcornmix

I’m pretty sure the default nfs buffer sizes are just what the linux kernel/debian has chosen.No one at RPi set the defaults to 1K.

Interesting - thanks very much for the clarification.

So I wonder why @DBMandrake was seeing that? The Debian defaults are, IIRC, 256K for both (E.g., that’s what you’ll see with a Debian NFS share mounted on a Debian NFS box, with no rsize or wsize specifications or anything else affecting the choice).

I think you’re both getting TCP and UDP confused - the default rsize and wsize are different for TCP and UDP.

[THEM]

@DBMandrake

Don’t confuse hardware accelerated checksum and other functions that modern networks cards do in hardware with the actual TCP stack itself. Put a standard network card in any Linux box and it is still the kernel that is generating TCP acks, and that takes CPU power to do so.

Heh!

Yes, a “standard” network card in any “Linux” box

As I said, slightly different backgrounds . Last system software Unix work I did was some porting to a Fujitsu box running UXP/M - liquid nitrogen cooled everything, 256bit wide data bus, … NIC hardware acceleration was not limited to calculating a few checksums .

[THEM]

@DBMandrake

I think you’re both getting TCP and UDP confused - the default rsize and wsize are different for TCP and UDP.

No, not getting them confused …

Yes, the sizes are different. TCP, the Debian default is 1M (NFSv4); UDP, it’s 32K (maximum allowed under NFSv3; this doesn’t apply to NFSv4 as that only supports TCP). I thought it was something like 256K for NFSv4, but it’s not; confirming by an actual test - E.g.:

root@Tip:~# mkdir /var/tmp/foo
root@Tip:~# touch /var/tmp/foo/bar
root@Tip:~#
root@Tip:~#
root@Tip:~# echo '/var/tmp/foo (rw)’ >> /etc/exports
root@Tip:~# exportfs -av
exportfs: /etc/exports [1]: Neither ‘subtree_check’ or ‘no_subtree_check’ specified for export ":/var/tmp/foo".
Assuming default behaviour (‘no_subtree_check’).
NOTE: this default has changed since nfs-utils version 1.0.x

exporting *:/var/tmp/foo
root@Tip:~# mount -t nfs -o ro,proto=udp,nfsvers=3 tip:/var/tmp/foo /mnt
root@Tip:~# nfsstat -m
/mnt from tip:/var/tmp/foo
Flags: ro,relatime,vers=3,rsize=32768,wsize=32768,namlen=255,hard,proto=udp,timeo=11,retrans=3,sec=sys,mountaddr=127.0.1.1,mountvers=3,mountport=34173,mountproto=udp,local_lock=none,addr=127.0.1.1

root@Tip:~#
root@Tip:~#
root@Tip:~#
root@Tip:~# uname -a
Linux Tip 3.16.0-4-amd64 #1 SMP Debian 3.16.7-ckt20-1+deb8u3 (2016-01-17) x86_64 GNU/Linux
root@Tip:~#

(see earlier in the thread for defaults using NFSv4).

That’s exactly what I’d expect to see and is in line with (up to date ) NFS documentation.

@popcornmix has said no-one at “rPi” would have changed it to 1K (and as I mentioned earlier, I wouldn’t hold it against anyone had they have done anyway - general purpose port, general purpose hardware, …).

I’m not disputing your having seen 1K as a default - I’m sure you’re perfectly capable of establishing these things. I’m just curious as to why you were seeing a 1K default when that isn’t the Debian default (for TCP or UDP based NFS of any sensible version) and it wasn’t changed by the porting team.

Just curiosity, that’s all.