NFS Performance

[Till Straumann]

Here's something (regarding default block size used by newlib/stdio) I 
found out:

If newlib was compiled with HAVE_BLKSIZE defined then it would use
the st_blksize information [newlib makebuf.c does a 'stat' anyways] when
configuring the default buffer for stdio.

Some filesystems (msdos, nfs) do set st_blksize, others (imfs) do not
but since libcsupport/src/stat.c does zero-out the stat buf argument
[and newlib uses BUFSIZ for st_bufsz <= 0] I believe defining
HAVE_BLKSIZE should be OK.

We could use this trick to let rtems NFS transparently increase the 
buffer size for
stdio to 8k (nfs v2 limit).

-- Till

Steven Johnson wrote:
> Till Straumann wrote:
>
>   
>> Joel Sherrill wrote:
>>
>>     
>>> Steven Johnson wrote:
>>>
>>>       
>>>> Joel, Thanks for the pointer. setvbuf worked like a treat.  So, we
>>>> don't
>>>> have to hack stdio.h, thanks for the suggestion.
>>>>
>>>>   
>>>>         
>>> I'm glad setvbuf worked.  It is always nice to not hack at a standard
>>> include file.
>>>
>>>       
>>>> Following are some benchmarks we got with different block sizes. 
>>>> MPC862
>>>> Processor (PowerPC) at 100Mhz, with 50Mhz SDRAM main memory and using
>>>> the FEC (Fast Ethernet Controller @ 100Mbit/s, full duplex), its a
>>>> custom design and doesn't use a standard BSP, but isn't dissimilar to
>>>> the standard MPC862 BSP:
>>>>
>>>> Times to transfer the 7.4M test file timed using ticks_since_boot, (1
>>>> tick is 10ms on our target):
>>>> Buffer Size @ Ticks to transfer = ~Mbit/s
>>>>
>>>> 256 @ 4265  = ~1.4Mbit/s
>>>> 512 @ 2221  = ~2.7Mbit/s
>>>> 1024 @ 1239 = ~4.8Mbit/s
>>>> 2048 @ 712 = ~8.4Mbit/s
>>>> 4096 @ 439 = ~13.7Mbit/s
>>>> 8192 @ 298 = ~20.2Mbit/s
>>>> 16384 @ 299 =~20.2Mbit/s
>>>> 32768 @ 298 =~20.2Mbit/s
>>>>   
>>>>         
>>>
>>> You don't mention what the NFS server is and how it does from
>>> a similar host.
>>>       
> The NFS Server is a Linux Box (Linux version 2.4.21-0.13mdk, Mandrake
> Linux 9.1)
>
> It is a 2.7Ghz P4 with 1GB of ram.
>
> Ethernet controller: Broadcom Corporation BCM4401 100Base-T.
>
> From a similarly spec'd Linux box, between the machines, we can sustain
> about 88Mbit/s NFS transfer rate, with a single file transfer.  Not
> unsurprisingly, given the sophisticated caching, etc in linux setvbuf
> has no effect on the speed of NFS on the linux box.  I don't know if the
> 20Mbit/s from our rtems box is a limit on our MPC862's processing
> performance or the performance of the FEC, or deficiencies in the NFS
> stack.  Probably all of the above.  Yet given the relative level's of
> complexity, 20Mbit/s is very respectable in my opinion.  It is certainly
> fast enough for our application's needs.
>
>   
>> done - I incorporated the comments I posted yesterday into the README.
>> Also, I added a test code.
>>
>> -- T. 
>>     
>
> That's great.  I'll throw up a Wiki topic on it soon.
>
> Steven J
>