Hannes Reinecke, on 08/06/2010 06:56 PM wrote:
But I can do bonnie runs in no time.
I have done some preliminary benchmarks by just enable ordered
queueing in sd.c and no other changes.
Bonnie says:
Writing intelligently: 115208 vs. 82739
Reading intelligently: 134133 vs. 129395
putc() performance suffers, though:
I get 52M vs 90M writing and 50M vs. 65M reading.
No idea why; shouldn't be that harmful here.
But in any case there is some speed improvement
to be had from using ordered tags.
Oh, and that was against an EVA 6400.
Here are my numbers. They are taken using:
fio --bs=X --ioengine=aio --buffered=0 --size=128M --rw=read --thread
--numjobs=1 --loops=100 --group_reporting --gtod_reduce=1 --name=AAA
--filename=/dev/sdc --iodepth=Y
/dev/sdc is 1GbE iSCSI device with on the other side iSCSI-SCST with a
single 15K RPM Wide SCSI HDD. All values are in MB/s. The system
(initiator) is pretty old 1.7GHz Xeon.
Y | 1 2 4 8 32
----------------------------------------------------------------------
X |
4K | 16 25 32 34 34 (initiator CPU overloaded)
16K | 25 57 72 85 85 (initiator CPU overloaded)
32K | 44 72 97 106 106 (initiator CPU overloaded)
64K | 65 95 114 115 115 (max of 1GbE)
128K | 80 112 115 115 115 (max of 1GbE)
Are there still any people thinking that tagged queuing doesn't have any
meaningful use?
Or 350% performance increase doesn't matter? (If the system was more
powerful, the difference would be even bigger.)
As you can see on external storage even with 128K commands the queue
should have at least 2 entries queued to go with full performance.
Vlad
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