From: "Jan Beulich" <JBeulich@novell.com>
To: "Avi Kivity" <avi@redhat.com>
Cc: <a.p.zijlstra@chello.nl>, "Ingo Molnar" <mingo@elte.hu>,
<tglx@linutronix.de>, <torvalds@linux-foundation.org>,
<mingo@redhat.com>, <npiggin@suse.de>,
<linux-kernel@vger.kernel.org>,
<linux-tip-commits@vger.kernel.org>, <hpa@zytor.com>
Subject: Re: [tip:core/locking] locking, x86: Slightly shorten __ticket_spin_trylock()
Date: Wed, 02 Dec 2009 14:59:42 +0000 [thread overview]
Message-ID: <4B168EEE02000078000230D5@vpn.id2.novell.com> (raw)
In-Reply-To: <4B167B77.8030502@redhat.com>
>>> Avi Kivity <avi@redhat.com> 02.12.09 15:36 >>>
>On 12/02/2009 04:25 PM, Jan Beulich wrote:
>>>>> Avi Kivity<avi@redhat.com> 02.12.09 15:12>>>
>>>>>
>>> Wouldn't 'u8 ret', as an additional argument be sufficient? gcc still
>>> ought to be able to use the same register for new and ret if we remove
>>> the early clobber.
>>>
>> We can't (validly) remove the early-clobber, otherwise the compiler
>> would be permitted to use a register also used for addressing the lock
>> structure for "new".
>>
>
>I meant for 'ret'.
But unless you drop the early-clobber on new, the compiler will have
to allocate another register, which I think is not desirable here.
Jan
next prev parent reply other threads:[~2009-12-02 14:59 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-11-27 15:09 [PATCH] x86: slightly " Jan Beulich
2009-12-02 10:45 ` [tip:core/locking] locking, x86: Slightly " tip-bot for Jan Beulich
2009-12-02 13:29 ` Ingo Molnar
2009-12-02 14:06 ` Jan Beulich
2009-12-02 14:12 ` Avi Kivity
2009-12-02 14:25 ` Jan Beulich
2009-12-02 14:36 ` Avi Kivity
2009-12-02 14:59 ` Jan Beulich [this message]
2009-12-02 14:21 ` Ingo Molnar
2009-12-02 14:57 ` Jan Beulich
2009-12-02 15:33 ` Linus Torvalds
2009-12-02 15:26 ` Linus Torvalds
2009-12-02 16:24 ` Jan Beulich
2009-12-02 16:56 ` Linus Torvalds
2009-12-02 17:05 ` Linus Torvalds
2009-12-02 17:23 ` H. Peter Anvin
2009-12-02 17:48 ` Linus Torvalds
2009-12-02 17:58 ` H. Peter Anvin
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