Re: + clocksource-increase-initcall-priority.patch added to -mm tree

On Sun, 2006-10-08 at 21:03 +0200, Thomas Gleixner wrote:
On Sun, 2006-10-08 at 10:17 -0700, Daniel Walker wrote:
There was a special case inside kernel/time/clocksource.c to prevent
clock switching during boot up. If you remove that (which I have) then
you will end up with clock switching happening a few times during bootup
(whenever a new highest rated clock is registered), that's the churn I'm
referring to.

The churn is not optimal. I've used postcore to prevent it, and make the
API usable earlier. So there is a reason for the change.

Yes, a bad one. The disabling had a totally different reason and you are
not listening at all.

I am listening, Thomas ..

You just introduce a problem again, because it does not happen on your
machines and you think, that some not yet available instrumentation code
needs high resolution time stamps.

Ok.

The reason why this was delayed into late boot is simply that the
unstable, unsynchronized TSC's made way too much trouble and the pmtimer
can not be initialized early.

I'm not going to accept that. Your change might work on 5 machines you
have tested on, but we start over with the same breakage we solved
already.

Your going to have to explain the breakage further. I don't recall
seeing any discussion on this.

This early boot instrumentation code can work with low resolution time
information quite well and none of the boot code does need any high res
time information. Boot code is different from a running system and has
different requirements.

This is a solution for a nonexisting problem, which just brings back
already solved ones.

There is at least one existing problem which it does solve. How about we
discuss the early TSC boot breakage, which you mention above, so I can
properly fix this situation.

Daniel

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

Relevant Pages

  • Re: + clocksource-increase-initcall-priority.patch added to -mm tree
    ... you will end up with clock switching happening a few times during bootup ... So there is a reason for the change. ... The reason why this was delayed into late boot is simply that the ... This early boot instrumentation code can work with low resolution time ...
    (Linux-Kernel)
  • Re: Where does GRUB reside ?
    ... boot code from the MBR - but not the partition table. ... I installed Ubuntu on another partition. ... found it now has GRUB boot code in the MBR. ...
    (comp.os.linux)
  • Re: Dual Boot Restore
    ... making a WinXP "boot" floppy before I formatted "C". ... > everything but the partition table and signature bytes is overwritten by ... > bootable partition, loads that partition's boot sector into memory, verifies ... the NT-style boot code required to boot into XP. ...
    (microsoft.public.windowsxp.setup_deployment)
  • Re: 2.6.23-rc4-mm1 and -rc6-mm1: boot failure on HP nx6325, related to clockevents
    ... patch and my collection of suspend patches applied, the box doesn't boot ... (the suspend patches don't even thouch the boot code, ... area is the C1E patch. ...
    (Linux-Kernel)
  • Re: Using a hard drive without partitions
    ... A i386-standard PC BIOS shouldn't, by itself, try to boot anything ... except the boot code in the MBR. ... for reading more boot code from the disk, without any partition table ...
    (freebsd-questions)