Cameron Harr wrote:
----
[root@test05 ~]# sgp_dd dio=1 if=/dev/zero of=/dev/fioa bs=512 bpt=2048
count=16777216 time=1
This is only 8 GB of IO. It is possible that (despite dio) you are
caching. Make the IO much larger than RAM. Use a count of 128m or so.
time to transfer data was 5.556115 secs, 1546.03 MB/sec
[root@test05 ~]# sg_dd dio=1 if=/dev/zero of=/dev/fioa bs=512 bpt=2048
count=16777216 time=1
time to transfer data: 5.565360 secs at 1543.46 MB/sec
[root@test05 ~]# dd oflag=direct if=/dev/zero of=/dev/fioa bs=1M count=8192
8589934592 bytes (8.6 GB) copied, 12.7761 seconds, 672 MB/s
We have found dd to be quite trustworthy with [oi]flag=direct.
----
Using iSer, with the small transfer chunks, sgp_dd has numbers that are in line
with what I'd expect for DIO while sg_dd doesn't:
---------
sgp_dd: 200.64 MB/s
sg_dd: 735.42 MB/s
dd: 62.3 MB/s
--------
But for larger transfers (with 1M block transfers), both sgp_dd and sg_dd show
well above what I think I can be getting:
-------
sgp_dd: 882.43
sg_dd: 819.89
dd: 731 MB/s #Which is still high, and which makes me suspect iSer
We had iSER bouncing from low 200s through 1000 MB/s during testing.
Very hard to pin down good stable benchmark times. This was a few
months ago.
--
Joseph Landman, Ph.D
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Scalable Informatics LLC,
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