Jens Axboe wrote:
On Sat, Sep 30 2006, Alan Cox wrote:
Ar Sad, 2006-09-30 am 20:04 +0200, ysgrifennodd Jens Axboe:
On Sat, Sep 30 2006, Tejun Heo wrote:
Turn off NCQ if queue depth is adjusted to 1.
I had thought of that too but discarded it - it would be nicer to have
an independent way of turning off NCQ. Say you are debugging a weird FIS
issue, NCQ depth 1 is still a different beast to non-NCQ. I see Jeff
already applied the patches, but just thought I'd voice my opinion.
I've got a blacklist for NCQ in my work tree but really we need the
vendors to help fill it. So far it has some raptors in it but I am sure
there are more, and I am sure there are cases we should be advising
newer firmware or just tweaking our queue sizes etc.
Lots of the older Maxtors are pretty crappy for NCQ, so those too. Queue
size tweaks fixed them for me (as low as 4, and I can't say for sure if
it fixes all crashes).
We have to be careful with the blacklisting - specifically, drive model
is often less critical than the version of the firmware (which gets
updated as people work drives through qualification, etc).
Updating drive firmware for end users is pretty rare (and almost all
tools are still DOS based ;-)).
Certain drives should default to non-NCQ (based on model), but we should
be able to enable it if the firmware supports it.
Most of the newest drives are fine, but we will still need something
like Tejun's fix to be able to turn it off for the odd cases that show
up in certain odd applications, etc.
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