<snip>
> It'is not possible to see the advantage of Tagged Queue with the benchmarks
> like Bonnie, Iozone, Test suite and Hdparm.
> I have done some simulations of multi-threaded hard disk load.
> I often have observed a gain less than 5 %.
> However, I have measured a gain of 25 % elapsed time while copying lots of
> files between 2 partitions of the same HD (Dec 1 giga byte).
> It seems that HD firmware is very important for Tagged Queue.
I've just enabled Taged Queueing on my AHA2940 (aic7xxx), and timed
doing several full kernel compiles with it enabled and disabled.
Enabling Tagged Queues actually seems to lower performance by around
3 or 4%. Are there any benchmarks out there to see how much the speed
is actually increasing/decreasing by?
The disk was a ST410800N, one of two on the internal SCSI bus. The
machine was rebooted before every test, and only had a single user
running on it.
Graham
Ask not what you can do for your country,
but what your government is doing to you