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NFS mounting rsize & wsize options ignored. Why?

openpli4 vu+duo2

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#1 macnuts

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Posted 11 January 2014 - 17:02

Hi,

 

Openpli4 on vu+duo2 (I do not think it matters really).

 

When I do a command like this:

mount -t nfs -o rw,nolock,tcp,rsize=32768,wsize=32768 '10.0.0.XXX:/volume1/NAME/' '/media/net/MOUNT_POINT'

I get this:

mount | grep MOUNT_POINT
10.0.0.XXX:/volume1/NAME/ on /media/net/MOUNT_POINT type nfs (rw,relatime,vers=3,rsize=8192,wsize=8192,namlen=255,hard,nolock,proto=tcp,port=65535,timeo=70,retrans=3,sec=sys,local_lock=all,addr=10.0.0.XXX)

Network drive is configured to allow such r/w sizes (it works from other clients like regular Ubuntu). 

 

Bigger values would help speed up of recording transfer. Please look into it.

 

Regards.



Re: NFS mounting rsize & wsize options ignored. Why? #2 Sjaaky

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Posted 11 January 2014 - 17:16

It might probably helps a tiny bit.

But the reason we limitted rsize and wsize is more important.

The network driver doesn't support scatter-gather, so it must allocate contiguous blocks of memory. Allocating 32k blocks proves to be problem on some boxes after they've been running for a while. We've seen OOM's while using nfs, which were solved by decreasing the rsize and wsize.



Re: NFS mounting rsize & wsize options ignored. Why? #3 MiLo

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Posted 11 January 2014 - 17:17

Bigger values lead to memory fragmentation and your box crashing. Hence, there's a patch to limit this to 8k in the kernel.
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Re: NFS mounting rsize & wsize options ignored. Why? #4 macnuts

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Posted 11 January 2014 - 17:24

Isn't vu+duo2 1GB RAM enough for bigger values? (I know box has 2 GB but only 1GB is available at the moment).


Edited by macnuts, 11 January 2014 - 17:26.


Re: NFS mounting rsize & wsize options ignored. Why? #5 theparasol

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Posted 11 January 2014 - 17:34

Isnt this workaround introduced for the dreambox 8000 specifically ? If so, why not enable it just for those boxes and leave all others run "cripple" free ?


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Re: NFS mounting rsize & wsize options ignored. Why? #6 WanWizard

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Posted 11 January 2014 - 17:47

None of the boxes have NIC drivers with scatter/gatter support.

 

The problem isn't that there isn't enough memory available, the problem is that there isn't enough continuous memory available, which the drivers need. They can't deal with fragmented memory, which is not a problem with these drivers on a linux desktop.

 

The less memory the box has, the sooner this becomes a problem. But eventually, it will become a problem for all...


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Re: NFS mounting rsize & wsize options ignored. Why? #7 macnuts

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Posted 11 January 2014 - 18:04

Ok. Thank you for comprehensive information.

 

Regards.



Re: NFS mounting rsize & wsize options ignored. Why? #8 Erik Slagter

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Posted 12 January 2014 - 10:08

And I must confirm Sjaaky's remark, enlarging the r/w size won't give you any extra speed (yes, I've tested it). A STB is whole other thing than a PC.


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Re: NFS mounting rsize & wsize options ignored. Why? #9 macnuts

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Posted 14 January 2014 - 17:10

Any idea how to speed up nfs connection? I never get higher transfer speeds than 12-14MB/s while at the same time with CIFS (I think, it is while copying in Windows Explorer) I get 30-40MB/s which is due to STB's HDD write speed limit.

 

I would like higher transfer speeds with nfs as I backup recordings on my NAS and the connection is of nfs type.

 

Regards.


Edited by macnuts, 14 January 2014 - 17:11.


Re: NFS mounting rsize & wsize options ignored. Why? #10 Erik Slagter

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Posted 14 January 2014 - 18:11

Some time ago we had a report from someone that also used a NAS and also didn't get maximum throughput using NFS with lower buffer sizes. When he updated the firmware of the NAS, the problem was gone. It's not something inherent to either NFS or linux, because I've never had this problem (using linux server as NAS).


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