From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Tejun Heo <tj@kernel.org>, Christoph Lameter <cl@linux.com>,
Pekka Enberg <penberg@kernel.org>, Ingo Molnar <mingo@elte.hu>,
Andrew Morton <akpm@linux-foundation.org>,
linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org,
Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [GIT PULL] slab fixes for 3.2-rc4
Date: Wed, 28 Dec 2011 21:25:10 +1100 [thread overview]
Message-ID: <1325067910.6632.42.camel@pasglop> (raw)
In-Reply-To: <CA+55aFyr69__vsorCXKZ7UezvXkCkZaot3=5b5xSHaYBEJ2ZKQ@mail.gmail.com>
On Wed, 2011-12-21 at 18:19 -0800, Linus Torvalds wrote:
> On Wed, Dec 21, 2011 at 9:05 AM, Tejun Heo <tj@kernel.org> wrote:
> >
> > machines. (cc'ing arch) Does anyone have better insight here? How
> > much more expensive are local irq save/restore compared to inc/dec'ing
> > preempt count on various archs?
>
> I think powerpc does sw irq disable, so it's pretty much the same.
On 64-bit only, but it's probably still better than going for an atomic
op, our atomics tend to be handled at the l2 level and so are sloooow.
.../...
> So I really suspect that we could just say: "make the irq-safe version
> be the *only* version", and no architecture will really care. Sure, it
> can be more expensive, but it usually isn't. Only when done badly and
> stupidly is it nasty.
Agreed, keep it simple, or we'll just grow more bugs like this one.
Cheers,
Ben.
next prev parent reply other threads:[~2011-12-28 10:25 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-11-29 18:02 [GIT PULL] slab fixes for 3.2-rc4 Pekka Enberg
2011-11-29 19:29 ` Linus Torvalds
2011-11-29 19:38 ` Linus Torvalds
2011-12-20 9:47 ` Pekka Enberg
2011-12-20 16:23 ` Tejun Heo
2011-12-20 16:31 ` Christoph Lameter
2011-12-20 19:28 ` Linus Torvalds
2011-12-20 20:28 ` Tejun Heo
2011-12-21 8:08 ` Pekka Enberg
2011-12-21 17:09 ` Tejun Heo
2011-12-21 15:16 ` Christoph Lameter
2011-12-21 17:05 ` Tejun Heo
2011-12-22 2:19 ` Linus Torvalds
2011-12-22 16:05 ` Tejun Heo
2011-12-28 10:25 ` Benjamin Herrenschmidt [this message]
2011-12-22 14:58 ` Christoph Lameter
2011-12-22 16:08 ` Tejun Heo
2011-12-22 17:58 ` Christoph Lameter
2011-12-22 18:03 ` Ingo Molnar
2011-12-22 18:31 ` Linus Torvalds
2011-12-23 16:55 ` Christoph Lameter
2011-12-23 20:54 ` Linus Torvalds
2012-01-04 15:30 ` Christoph Lameter
2012-01-04 16:07 ` Linus Torvalds
2012-01-04 17:00 ` Christoph Lameter
2012-01-04 23:10 ` Linus Torvalds
2012-01-05 19:15 ` Christoph Lameter
2012-01-05 19:27 ` Linus Torvalds
2011-12-22 18:47 ` Tejun Heo
2011-12-20 16:26 ` Christoph Lameter
2011-12-21 8:06 ` Pekka Enberg
2011-12-21 15:20 ` Christoph Lameter
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