From: Ingo Molnar <mingo@elte.hu>
To: Linus Torvalds <torvalds@osdl.org>
Cc: Arjan van de Ven <arjan@infradead.org>,
Andrew Morton <akpm@osdl.org>, Eric Dumazet <dada1@cosmosbay.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] i386 spinlocks should use the full 32 bits, not only 8 bits
Date: Fri, 21 Oct 2005 00:02:28 +0200 [thread overview]
Message-ID: <20051020220228.GA26247@elte.hu> (raw)
In-Reply-To: <Pine.LNX.4.64.0510201455030.10477@g5.osdl.org>
* Linus Torvalds <torvalds@osdl.org> wrote:
> On Thu, 20 Oct 2005, Ingo Molnar wrote:
> >
> > +/*
> > + * We inline the unlock functions in the nondebug case:
> > + */
> > +#ifdef CONFIG_DEBUG_SPINLOCK
>
> That can't be right. What about preemption etc?
>
> There's a lot more to spin_unlock() than just the debugging stuff.
the unlock is simple even in the preemption case - it's the _lock that
gets complicated there. Once there's some attachment to the unlock
operation (irq restore, or bh enabling) it again makes sense to keep
things uninlined, but for the specific case of the simple-unlocks, it's
a 0.2% space win to not inline - mostly from reduced clobbering of %eax,
%ecx, %edx. Should be less of a win on 64-bit CPUs with enough
registers.
Ingo
next prev parent reply other threads:[~2005-10-20 22:02 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-10-11 4:04 i386 spinlock fairness: bizarre test results Chuck Ebbert
2005-10-11 9:42 ` Eric Dumazet
2005-10-11 13:00 ` Alan Cox
2005-10-11 14:44 ` Linus Torvalds
2005-10-11 15:32 ` [PATCH] i386 spinlocks should use the full 32 bits, not only 8 bits Eric Dumazet
2005-10-11 16:03 ` Linus Torvalds
2005-10-11 16:36 ` Eric Dumazet
2005-10-11 16:54 ` Linus Torvalds
2005-10-11 16:55 ` Linus Torvalds
2005-10-17 7:03 ` Andrew Morton
2005-10-17 7:20 ` Arjan van de Ven
2005-10-20 21:50 ` Ingo Molnar
2005-10-20 21:57 ` Linus Torvalds
2005-10-20 22:02 ` Ingo Molnar [this message]
2005-10-20 22:15 ` Linus Torvalds
2005-10-20 22:27 ` Ingo Molnar
2005-10-20 22:44 ` Andrew Morton
2005-10-20 22:53 ` Ingo Molnar
2005-10-20 23:01 ` Andrew Morton
2005-10-20 23:26 ` Ingo Molnar
2005-10-27 16:54 ` Paul Jackson
2005-10-11 17:59 ` Andi Kleen
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