Re: [patch] 2.6.5 Improve interrupt handling on contended spinlocks

From: David Mosberger <davidm_at_napali.hpl.hp.com>
Date: 2004-04-10 02:07:54
>>>>> On Fri, 09 Apr 2004 17:42:11 +1000, Keith Owens <kaos@sgi.com> said:

  Keith> On Thu, 8 Apr 2004 17:07:44 -0700, David Mosberger
  Keith> <davidm@napali.hpl.hp.com> wrote:
  >>>>>>> On Thu, 08 Apr 2004 13:19:37 +1000, Keith Owens
  >>>>>>> <kaos@sgi.com> said:
  >>
  Keith> spin_lock_irqsave() on a contended lock leaves interrupts
  Keith> disabled while waiting for the lock.  If the interrupts were
  Keith> enabled before spin_lock_irqsave then this has the nasty side
  Keith> effect of preventing interrupt handling while waiting for the
  Keith> lock.  Change the contention path to enable interrupts if it
  Keith> is safe to do so, allowing the cpu to process interrupts
  Keith> while waiting for the lock.
  >>  Seems like a reasonable thing to me.  I'm fine with the
  >> ia64-specific bits, so I guess the only question is whether the
  >> linux/spinlock.h bits will be accepted.

  Keith> Catch 22.  The ia64 code cannot be changed without the change
  Keith> to linux/spinlock.h, that change cannot be justified without
  Keith> at least one architecture using it.  David, could you send
  Keith> the change to Linus as an ia64 patch, other architectures can
  Keith> define _raw_spin_lock_flags if they want it.

No, it's not a catch 22.  Just send the patch upstream and tell them
the ia64-portion has my approval.  I just don't have time at the
moment to push this patch on.

	--david
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Received on Fri Apr 9 12:08:18 2004

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