Jeff Garzik wrote:
It looks like we will need to implement an "impatient probe".
I have an SiI PATA<->SATA bridge that requires DMADIR to enable ATAPI.
When ATAPI_ENABLE_DMADIR is -not- enabled, it makes a good test case for
the EH :)
See the attached dmesg output, which illustrates that the boot is slowed
by several minutes. It would be ideal if we could execute EH in the
background during probe, and simply stop waiting if it takes too long.
bootplug should handle any devices that appear after the bus probe gets
"too impatient", and stops waiting.
I've encountered similar problems w/ my broken harddisks. I am thinking
of the followings.
* implement parallel probing as SCSI does.
* Make EH parametrized by timeouts. We currently use single worst-case
timeout for all tries. I think we need to use shorter timeouts for
early tries. This is also true for normal (non-probing) EHs. When
device or controller goes dumb, the current EH is way too generous about
timeouts.
* A related problem is spinup waiting after hotplug for controllers
which misses the first D2H FIS. libata currently waits 8 secs
unconditionally. If the drive is ready after that, everything is good.
If not, it ends up timing out after 30secs and then retries. I think
this can be done much better by trying at 5, 10, 15 and 30 secs from
hotplug event.
Even if we decide to implement the aboves, I guess both are 2.6.19
materials.
--
tejun
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