Terrible NFS performance under 9.2-RELEASE?

[Rick Macklem]

J David wrote:
> On Fri, Jan 31, 2014 at 6:16 PM, Rick Macklem <rmacklem at uoguelph.ca>
> wrote:
> > You can certainly try "-o rsize=61440,wsize=61440" (assuming a 4K
> > page size)
> > for the mount, if you'd like.
> 
> This has previously been tested with all 4k steps between 16k and
> 32k.
>  All of them perform worse than
> 
> With 61440, NFS fails outright on the random read test:
> 
> $ iozone -e -I -s 1g -r 4k -i 0 -i 2
> 
> Iozone: Performance Test of File I/O
> 
>         Version $Revision: 3.420 $
> 
> Compiled for 64 bit mode.
> 
> Build: freebsd
> 
> [...]
> 
> Include fsync in write timing
> 
> O_DIRECT feature enabled
> 
> File size set to 1048576 KB
> 
> Record Size 4 KB
> 
> Command line used: iozone -e -I -s 1g -r 4k -i 0 -i 2
> 
> Output is in Kbytes/sec
> 
> Time Resolution = 0.000005 seconds.
> 
> Processor cache size set to 1024 Kbytes.
> 
> Processor cache line size set to 32 bytes.
> 
> File stride size set to 17 * record size.
> 
>                                                             random
> random    bkwd   record   stride
> 
>               KB  reclen   write rewrite    read    reread    read
> write    read  rewrite     read   fwrite frewrite   fread  freread
> 
>          1048576       4   24688   23891
> 
> Error reading block at 1073729536
> 
> read: Bad file descriptor
> 
> 
> Upon using the -w option, which leaves the file intact on exit, it's
> possible to see that it's not even 1gig in length:
> 
> $ ls -aln iozone.tmp
> 
> -rw-r-----  1 1000  0  1073709056 Feb  1 01:18 iozone.tmp
> 
> 
> It's 32k short, which is a pretty surprising result.
> 
Ok, I knew that non-powers of 2 could result in problems. I thought
they only occurred when the size wasn't an exact multiple of page
size, but it seems there are non-power of 2 problems.

rick

> Thanks!
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