Mark Lord wrote:
Rafael J. Wysocki wrote:
On Tuesday, 4 of November 2008, Linus Torvalds wrote:
On Tue, 4 Nov 2008, Jeff Garzik wrote:
This adds code at a late stage (heading towards -rc4), but does
eliminate a particular spin-up overcycling behavior associated with
hibernation.
What does this have to do with hibernation?
If it's a hibernation-only issue, then there is something wrong.
No, it is not. On some machines it is a power-off issue, on the
others it is
hibernation and power-off issue.
Also, if it is an issue for normal power-off as well, then I wonder
why this isn't an issue on Windows. Does windows not spin down disks
at all?
In fact, AFAICS, it is an issue on Windows as well, at least if
other-than-HP-preloaded version of Windows is used.
IOW, I really don't think this is correct.
I _do_ think that correct might be:
- maybe we just do something odd and different, triggering some BIOS
behavior that isn't there under Windows.
So we should power down thigns differently so that the BIOS.
- quite possibly: we just should not spin down disks at all, and
just flush them and do the "park" command thing. If we're _really_
powering off, the disks will spin down on their own when power
goes away. Maybe that's what Windows does?
So I really don't want to pull this, because I want to get more of an
explanation for why we need to do this at all. I also don't think
this is even appropriate at this stage in -rc.
Is it a regression? If so, that just strengthens the questions above
- what did _we_ start doing wrong that this is needed at all? Let's
just stop doing that, not add some idiotic black-list for somethign
that _we_ do wrong.
This is a regression, but from something like 2.6.25 or even earlier.
I think what happened is we started to power-off disks at one point
and these
BIOS-es just don't like that.
[Note that the issue only appears in _some_ HP boxes, other vendors don't
seem to be affected at all.]
.
So, what happens if we just don't ever spin them down from the kernel?
Presumably they still spin-down normally (HP or otherwise) when the BIOS
actually cuts the power at the end of all of this?
Just curious..
On many disks (especially laptops) just cutting the power without
spinning the disk down is a bad thing to do, as it causes an emergency
head unload which causes much more disk wear than a normal controlled
unload (which a commanded spindown causes). This is much worse than the
problem here, where the disk is spun down, spun up and down again.
On these systems, not spinning the disk down is fine because the BIOS
does it. However this would cause problems on systems where the BIOS
doesn't do so as it will cause an emergency unload on power-down.
From what I have heard, the problem on the HP laptops is thought to be
something to do with the disk spinning up and back down when it gets an
IDLE IMMEDIATE command (from the BIOS' SMI code, or whatever it is) when
it's already spun down (by the kernel). If that's truly the case it's
pretty retarded behavior on the disk's part..
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