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

Henrique de Moraes Holschuh linux-thinkpad@linux-thinkpad.org
Wed, 25 Jun 2008 14:01:52 -0300

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
just released, it is supposed to fix a performance regression in the

If the regression in hdparm -T speed is indeed related to ZEROPAGE, that
means hdparm -T is a completely meaningless test.

> 	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.

  "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