[ltp] Thinkpad T43 cached read Speed(hdparm -T) mystery

[linux-thinkpad@linux-thinkpad.org]

On Wed, Jun 25, 2008 at 02:01:52PM -0300, Henrique de Moraes Holschuh wrote:
> On Wed, 25 Jun 2008, jqian@physics.harvard.edu wrote:
> > When it was running a Ubuntu hoary a few months ago(too lazy to 
> > update), with vanilla 2.6.18 kernel, hdparm -T shows about 1800MB/sec.  
> > However, now I'm in hardy, with ubuntu 2.6.24-18 kernel, the hdparm -T 
> 
> Might be the ZEROPAGE removal stuff that went in in 2.6.24-18.  Try 2.6.25.9
> just released, it is supposed to fix a performance regression in the
> ZEROPAGE issue.
> 
> If the regression in hdparm -T speed is indeed related to ZEROPAGE, that
> means hdparm -T is a completely meaningless test.
I'm sorry to be a bit dense here, but if 2.6.25.9 fix a "performance 
regression", then what hdparm -T detects is a real regression, not a 
meaningless test, right?
> 
> > 	2.What exactly does hdparm -T measure(processor bus speed?)?  
> 
> Probably nothing useful.
> 
> > Is it a good gauge for performance? If it is not a good guage for 
> > performance, what is?
> 
> Your real workload is the only gauge for performance that matters.
It's hard for me to judge performances when I had distro change, is 
there some benchmark that more sensibly reflect the bus speed of my 
computer?
Thanks a lot.
Jiang
> 
> -- 
>   "One disk to rule them all, One disk to find them. One disk to bring
>   them all and in the darkness grind them. In the Land of Redmond
>   where the shadows lie." -- The Silicon Valley Tarot
>   Henrique Holschuh
> -- 
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