On 01/11/2008 12:00, Justin Piszcz wrote:
On Sat, 1 Nov 2008, John Robinson wrote:
On 01/11/2008 08:29, Justin Piszcz wrote:
[...]
Why is running 3 jobs con-currently that take care of two parts each
more than
twice as fast than running one job for six parts?
Because you have multiple CPUs?
So 1/4 of a quad core q6600 cannot achieve higher rates of I/O due to the
parity operations being that costly?
Is the only way to increase the single-threaded speed to increase the
maximum
CPU core speed/get a faster CPU, and/or theoretically a multi-threaded
md-raid
could maximize throughput?
Actually I was thinking that your test job - I think you said it used
tar - is single-threaded and CPU-bound on one core, and doesn't saturate
the MD subsystem. Your jobs are 75% user time to 25% system time, and
the user time is not parellelisable until you do it yourself by
splitting the work up.
Cheers,
John.
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