Re: libata sata_via unusual behaviour

[Mark Lord <liml@rtr.ca>]

Alan Cox wrote:
> On Thu, 1 May 2008 20:58:37 +0200
> Paolo <paoletto@gmail.com> wrote:
> 
>> Hello!
>>
>>  It seems that me and many others are experiencing poor sata performances
>>  in the last months, probably with 2.6.20+ kernels.
>>
>>  an example of these problems is here:
>>
>>  http://ubuntuforums.org/showthread.php?p=4845777
>>
>>  unfortunately it seems that sata subsystem on linux is little to none
>>  tweakable
> 
> It doesn't normally need tweaking, and the hdparm numbers show that it is
> working correctly in the example you give. There may be problems higher
> up the stack but the ATA layer appears to be doing just fine.
..

Yup.  The drive seems to be doing fine, according to the info you've provided.

But the "-T" (big T) number looks *very* slow:  220.02 MB/sec
That number has nothing to do with the drive.  Rather, it's an indication
of how fast the CPU and memory are together, and that's about 1/20 to 1/10
of a modern system.

Note that it's not a useful number in any absolute sense, but only when
compared with a "-T" value from some other system or Linux distro.

Strange.