On Mon, Apr 15 2002, Jens Axboe wrote:
> On Mon, Apr 15 2002, Jens Axboe wrote:
> > On Mon, Apr 15 2002, Aaron Tiensivu wrote:
> > > Simple question but hopefully it has a simple answer.. is there a command
> > > you can issue or flag you can look for from the output of hdparm to tell if
> > > your hard drive is capable of TCQ before installing the patch? I have a few
> > > IBM drives that I'm sure have TCQ abilities but I don't trust them as far as
> > > I can throw them (being Hungarian and cursed) but I'd like to give TCQ a
> > > whirl on my WD 120GB drives that should work OK, if they support TCQ..
> > >
> > > Sorry if it's already been asked.. :)
> >
> > It has not been asked :-)
> >
> > You can run a IDENTIFY_DEVICE from user space with the task ioctls and
> > look at word 83 -- bit 1 and 14 must be set for TCQ to be supported. If
> > you give me the model identifier from the IBM drive, I can tell you if
> > it has tcq or not...
> >
> > I'll write a small util to detect this tomorrow and send it to you + the
> > list.
>
> Duh, you can of course just look at /proc/ide/ideX/hdY/identify and
> parse that. The info above is still valid for that, of course :-)
Recent versions of hdparm ( 4.x like shipped with recent redhat linux )
give a nice report about this :
hdparm -I /dev/hda ( or maybe it is the -i option )
Interestingly , on my system it also says that both my ATAPI CD-ROMs
( one is a CD-RW : Acer 1208A , the other is a CD-ROM : Teac CDR-532E-B
)
support ATA command overlap ( maybe queuing too, I don't recall right
now ).
Is overlapping supported in current TCQ code ? If not, will it be ?
It would be cool to access one drive in the seconds while the other
tries to
read a sector ( time from sending the read command, disc spinning up,
reading and delivering the sector can be up to 2 seconds ! )
Best regards,
david balazic