Re: scsi-idle

Manuel J. Galan (manolow@step.es)
Sat, 01 Aug 1998 15:34:14 +0100 (WEST)


On 01-Aug-98 Pavel Machek wrote:
> Hi!
>
>
> Few more quick questions: why do you have special ioctl to get idle
> time and why do you measure idle time in kernel? In ide case
> (bdflush-1.6.2), we do this in userland using /proc/stat. I would like
> to do it similar in scsi case.

1- Your implementation seems to be only for one device..(what about several
disks, some md groups, swap only disks, etc...)

2- To spin up/down ide disks on a specific idle time using hdparm, I think that
you do not need all that rc.spin[up/down] thing, as using
'hdparm -qS timeout /dev/hdx' seems to be enough. (It works like a charm in
my ThinkPad 760XD)

>
> Also, we should not need any code in kernel for spindown, scsi generic
> device should be enough for this one.
>
> Only remaining issue is spinup, which needs to be in kernel; but I
> believe it already is there, anyway (JAZ support).
>

Yes, indeed, please see scsi-idle.c (the userland daemon...).

The rest of the kernel patch is to handle gracefuly the spin
up of _nonremovable_ scsi media (jaz spins down by itself
and spins up on kernel request but it _is_ removable media)

The patch is not mine at all, I've only put it together for 2.1.112,
but I think that this (or something alike) is needed before 2.2...

SCSI gurus out there...

~~~
Manuel J. Galan <manolow@step.es>
Sent on 01-Aug-98.
~~~
I live the way I type; fast, with a lot of mistakes.

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