fibreraid@xxxxxxxxx wrote:
Hi Shehjar,
Can you provide the exact dd command you are running both locally and
for the NFS mount?
on the ssd:
# dd if=/dev/zero of=bigfile4 bs=1M count=1000
1000+0 records in
1000+0 records out
1048576000 bytes (1.0 GB) copied, 0.690624 s, 1.5 GB/s
# dd if=/dev/zero of=bigfile4 bs=1M count=1000 oflag=direct
1000+0 records in
1000+0 records out
1048576000 bytes (1.0 GB) copied, 1.72764 s, 607 MB/s
The ssd file system is ext4 mounted as
(rw,noatime,nodiratime,data=writeback)
Here is another strangeness, using oflag=direct gives better performance:
On nfs mount:
# dd if=/dev/zero of=/tmp/testmount/bigfile3 bs=1M count=1000 oflag=direct
1000+0 records in
1000+0 records out
1048576000 bytes (1.0 GB) copied, 3.7063 s, 283 MB/s
# rm /tmp/testmount/bigfile3
# dd if=/dev/zero of=/tmp/testmount/bigfile3 bs=1M count=1000
1000+0 records in
1000+0 records out
1048576000 bytes (1.0 GB) copied, 9.66876 s, 108 MB/s
The kernel on both server and client is 2.6.32-23, so I think this
regression might be in play.
http://thread.gmane.org/gmane.comp.file-systems.ext4/20360
Thanks
-Shehjar
-Tommy
On Wed, Nov 3, 2010 at 11:33 AM, Joe Landman <joe.landman@xxxxxxxxx> wrote:
On 11/03/2010 01:58 PM, Shehjar Tikoo wrote:
Hi All,
I am running into a performance problem with 2.6.32-23 Ubuntu lucid on
both client and server.
The disk is an SSD performing at 1.4 - 1.6Gbps for a dd of a 6gb file in
64k blocks.
If the size of this file is comparable to or smaller than the client or
server ram, this number is meaningless.
The network is performing fine with many Gbps of iperf throughput.
GbE gets you 1 Gbps. 10GbE may get you from 3-10 Gbps, depending upon many
things. What are your numbers?
Yet, the dd write performance over the nfs mount point ranges from 96-105
Mbps for a 6gb file in 64k blocks.
Sounds like you are writing over the gigabit, and not the 10GbE interface.
I've tried changing the tcp_slot_table_entries and the wsize but there is
negligible gain from these.
Does it sound like a client side inefficiency?
Nope.
--
Joseph Landman, Ph.D
Founder and CEO
Scalable Informatics Inc.
email: landman@xxxxxxxxxxxxxxxxxxxxxxx
web : http://scalableinformatics.com
phone: +1 734 786 8423 x121
fax : +1 866 888 3112
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