Hi Benny,
> According to dd's man page, the f{,date}sync options tell it to
> "physically write output file data before finishing"
> If you kill it before that you end up with dirty data in the cache.
> What exactly are you trying to measure, what is the expected application
> workload?
I changed my test to do what you were doing instead of killing
dd's, etc. The end application is DB2 and it is using multiple
processes and I wanted to simulate that with micro-benchmarks.
The only reliable way to benchmark bandwidth for multiple
processes is to kill the tests after running them for some time
instead of letting them run till conclusion.
> ext3 mount options: noatime
> nfs mount options: rsize=65536,wsize=65536
> dd options: bs=64k count=10k conv=fsync
>
> (write results average of 3 runs)
> write local disk: 47.6 MB/s
> write loopback nfsv3: 30.2 MB/s
> write remote nfsv3: 29.0 MB/s
> write loopback nfsv4: 37.5 MB/s
> write remote nfsv4: 29.1 MB/s
>
> read local disk: 50.8 MB/s
> read loopback nfsv3: 27.2 MB/s
> read remote nfsv3: 21.8 MB/s
> read loopback nfsv4: 25.4 MB/s
> read remote nfsv4: 21.4 MB/s
I used the exact same options you are using, and here is the results
averaged across 3 runs:
Write local disk 58.5 MB/s
Write loopback nfsv3: 29.42 MB/s (50% drop)
Reading (file created from /dev/urandom, somehow I am getting in GB/sec
while your results were comparable to write's):
Read local disk: 2.77 GB/s
Read loopback nfsv3: 2.86 GB/s (higher for some reason)
Thanks,
- KK
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