Others have already answered with good information, but I also wanted to
mention that cp is slow for PVFS on some systems in part due to using
buffer sizes that are too small. You might get better command line
performance using "dd bs=4M ..." instead of "cp" to copy data from /tmp
to /mnt/pvfs2. The dd that you are using for /tmp works fine with a
small transfer size of 1024 because of caching effects combined with low
latency to local storage.
The lack of client-side caching in PVFS works against it on serial
benchmarks, but it comes back around to being a positive on large
parallel benchmarks.
-Phil
On 04/16/2010 09:25 AM, Christian Baun wrote:
Hi,
I created 2 Instances. 1 Instance has an EBS-Volume attached. The EBS-Volume is
the storage for the PVFS2. Both instances (m1.large) are inside EC2 us-east-1a.
The performance looks quite well for large files:
# mount | grep pvfs
/dev/sdc on /pvfs2-storage-space type ext3 (rw)
tcp://domU-12-31-38-00-4A-42:3334/pvfs2-fs on /mnt/pvfs2 type pvfs2 (rw)
# dd if=/dev/zero of=/tmp/testfile bs=1024 count=1000000
1000000+0 records in
1000000+0 records out
1024000000 bytes (1.0 GB) copied, 6.83677 s, 150 MB/s
# pvfs2-cp -t /tmp/testfile /mnt/pvfs2/
Wrote 1024000000 bytes in 24.781117 seconds. 39.407525 MB/seconds
When using the PVFS2 Linux Kernel Interface it need much longer:
# time cp /tmp/testfile /mnt/pvfs2/test
real 2m2.695s
user 0m0.000s
sys 0m0.020s
Any ideas why it needs so much longer when using the Linux Kernel Interface and
how to benchmark the performance in a better way?
:-)
Best Regards,
Christian
Am Donnerstag, 15. April 2010 schrieb Emmanuel Florac:
Le Thu, 15 Apr 2010 22:51:00 +0200 vous écriviez:
Thanks a lot!!!
Now the module is built. :-)
Good luck :) I'm interested in knowing how pvfs performs on EC2...
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