From: Peter Zijlstra <a.p.zijlstra@chello.nl>
To: mingo@kernel.org, hpa@zytor.com, linux-kernel@vger.kernel.org,
torvalds@linux-foundation.org, shai@scalemp.com,
akpm@linux-foundation.org, tglx@linutronix.de, ido@wizery.com
Cc: linux-tip-commits@vger.kernel.org
Subject: Re: [tip:x86/mm] x86/pat: Avoid contention on cpa_lock if possible
Date: Wed, 06 Jun 2012 19:24:03 +0200 [thread overview]
Message-ID: <1339003443.23343.6.camel@twins> (raw)
In-Reply-To: <tip-d2956406fb61e15ad2b47eda823288db4996acf1@git.kernel.org>
On Wed, 2012-06-06 at 09:18 -0700, tip-bot for Shai Fultheim wrote:
> [ I absolutely hate these locking patterns ... yet I have no better idea. Maybe the gents on Cc: ... ]
> Signed-off-by: Ingo Molnar <mingo@kernel.org>
Oh yuck, this is vile..
static struct static_key scale_mp_trainwreck = STATIC_KEY_INIT_FALSE;
static DEFINE_SPINLOCK(_cpa_lock);
static inline void cpa_lock(void)
{
if (static_key_false(&scale_mp_trainwreck))
return;
spin_lock(&_cpa_lock);
}
static inline void cpa_unlock(void)
{
if (static_key_false(&scale_mp_trainwreck))
return;
spin_lock(&_cpa_lock);
}
And then use cpa_{,un}lock(), and the scale-mp guys can
static_key_slow_inc(&scale_mp_trainwreck).
[ and yes I hate those jump_label names ... but I'm not wanting
to go through another round of bike-shed painting. ]
next prev parent reply other threads:[~2012-06-06 17:24 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-04-06 12:40 [PATCH] x86: Avoid contention on cpa_lock if possible Ido Yariv
2012-04-19 22:11 ` [PATCH RESEND] " Ido Yariv
2012-05-05 23:49 ` Ido Yariv
2012-06-02 18:56 ` Ido Yariv
2012-06-06 16:18 ` [tip:x86/mm] x86/pat: " tip-bot for Shai Fultheim
2012-06-06 17:24 ` Peter Zijlstra [this message]
2012-06-06 17:41 ` Ingo Molnar
2012-06-06 18:58 ` H. Peter Anvin
2012-06-06 22:18 ` Shai Fultheim (Shai@ScaleMP.com)
2012-06-06 23:05 ` Ido Yariv
2012-06-06 23:07 ` Shai Fultheim (Shai@ScaleMP.com)
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