Re: hdparm and DMA
On Tue, 19 Nov 2002, mdevin wrote:
> # hdparm -tT /dev/hda
> /dev/hda:
> Timing buffer-cache reads: 128 MB in 0.46 seconds =278.26 MB/sec
> Timing buffered disk reads: 64 MB in 16.12 seconds = 3.97 MB/sec
>
> Thus all the same as before whether turned on or off. I also tried
> setting MultiSect to max of 16 (which hdparm -i told me it could do),
> but this didn't change things either.
>
> So are the read times as expected for an IDE ATA133, 7200RPM, 40GB drive?
> This is one of the faster IDE drives now isn't it?
P4 2.4ghz, Quantum AS 40 gig, using the onboard PDC 20726 controller
# hdparm -Tt /dev/hdg
/dev/hdg:
Timing buffer-cache reads: 128 MB in 0.34 seconds =376.47 MB/sec
Timing buffered disk reads: 64 MB in 1.93 seconds = 33.16 MB/sec
Out of curiosity, one of the backup servers here, P120 with an 80 gig
Maxtor D740X drive, connected to a PIIX3 controller.
# hdparm -Tt /dev/hdc
/dev/hdc:
Timing buffer-cache reads: 128 MB in 4.26 seconds = 30.05 MB/sec
Timing buffered disk reads: 64 MB in 7.52 seconds = 8.51 MB/sec
As you can see, cpu and memory bandwidth make a tremendous difference on
speeds. :)
I wonder if this drive of yours is in the blacklist on DMA usage?
Mike
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