DSD 128 from NAS stuttering

[Tim Curtis]

Where is this param [size=262144] input?

[TheOldPresbyope]

@Tim Curtis

Hi, Tim.

It's the rsize= parameter in the Advanced section of the Configure>Library>Music Source panel for SMB shares.

I'm not sure what a max number ought to be. I haven't gathered enough data [1] from my own system and the InterWeb™ is full of (mis)information depending on the NAS, the OS, etc.

Here's what the man page for current Rasbian's mount.cifs says:

Code:

rsize=bytes
             Maximum  amount  of  data that the kernel will request in a read
             request in bytes. Prior to kernel 3.2.0, the  default  was  16k,
             and  the  maximum  size was limited by the CIFSMaxBufSize module
             parameter. As of kernel 3.2.0, the behavior varies according  to
             whether POSIX extensions are enabled on the mount and the server
             supports large POSIX reads. If they are, then the default is 1M,
             and the maximum is 16M. If they are not supported by the server,
             then the default is 60k and the maximum is around 127k. The rea‐
             son  for the 60k is because it's the maximum size read that win‐
             dows servers can fill. Note that this value is  a  maximum,  and
             the  client may settle on a smaller size to accommodate what the
             server supports. In kernels prior to 3.2.0,  no  negotiation  is
             performed.

I arbitrarily chose 262144 because it had cropped up in a discussion elsewhere of a problem someone was having with (I think) Red Hat Linux. Since the actual size is negotiated during a mount it would seem important only to make sure it's big enough to not limit what Raspbian and Synology (or whatever NAS is in play) can negotiate.

There's no such thing as a free lunch, of course; I'm sure there's a downsize to having the negotiated number be too big. I don't know what it is.

Regards,
Kent

[1] e.g., keep bumping the number and see what size is actually negotiated during the mount.

[TheOldPresbyope]

PS - it should be apparent that the smaller the size, the greater the number of SMB READ requests will be issued while playing a given file. These request and response messages contribute to these protocols being "chatty", hence consuming bandwidth.

[jordanhuai]

Finally, I found the problem. A broken lan port 2 (or may be the ethernet cable)cause pi running 10Mbps link all the time. Change to port 3 and a new ethernet cable, It is running at 1000Mbps as it should. DSD128 & DSD 256 are running smooth. I still don't understand why cat5e cable and gigabit ports give me 10Mbps link. LOL. Thanks a lot of for helping me out!

[Tim Curtis]

Nice :-)