From: george anzinger <george@mvista.com>
To: Arjan van de Ven <arjanv@redhat.com>
Cc: Linus Torvalds <torvalds@transmeta.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 1/3] High-res-timers part 1 (core) take 20
Date: Mon, 09 Dec 2002 22:55:45 -0800 [thread overview]
Message-ID: <3DF58FF1.9C3A5BF3@mvista.com> (raw)
In-Reply-To: <20021209073434.A24382@devserv.devel.redhat.com>
Arjan van de Ven wrote:
>
> On Mon, Dec 09, 2002 at 04:27:56AM -0800, george anzinger wrote:
> > >
> > > that's why spinlocks are effectively nops on UP.
> > > What you say is true of just about every spinlock user, and no
> > > they shouldn't all do some IF_SMP() thing; the spinlock itself should be
> > > (and is) zero on UP
> >
> > But with preemption, they really are not nops on UP...
>
> that doesn't justify fuglyfying the kernel code. If you can't live
> with the overhead of preemption, disable preemption. Simple.
> We DON'T want
> spin_lock_nop_on_preempt()
> ...
>
> spin_unlock_nop_on_preempt()
>
> really, I don't, and I can't see anyone else wanting that either
Well, I just thought it was an optimization. I will leave
it the way it is.
--
George Anzinger george@mvista.com
High-res-timers:
http://sourceforge.net/projects/high-res-timers/
Preemption patch:
http://www.kernel.org/pub/linux/kernel/people/rml
prev parent reply other threads:[~2002-12-10 6:48 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-12-08 7:46 george anzinger
2002-12-08 9:50 ` Arjan van de Ven
2002-12-09 7:03 ` george anzinger
2002-12-09 8:21 ` Robert Love
2002-12-09 8:53 ` Arjan van de Ven
2002-12-09 12:27 ` george anzinger
2002-12-09 12:34 ` Arjan van de Ven
2002-12-10 6:55 ` george anzinger [this message]
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