From: Ingo Molnar <mingo@elte.hu>
To: Christoph Lameter <cl@linux.com>
Cc: Tejun Heo <tj@kernel.org>, Thomas Gleixner <tglx@linutronix.de>,
Linus Torvalds <torvalds@linux-foundation.org>,
Pekka Enberg <penberg@kernel.org>, Jens Axboe <axboe@kernel.dk>,
Andrew Morton <akpm@linux-foundation.org>,
werner <w.landgraf@ru.ru>, "H. Peter Anvin" <hpa@zytor.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [block IO crash] Re: 2.6.39-rc5-git2 boot crashs
Date: Thu, 5 May 2011 21:13:53 +0200 [thread overview]
Message-ID: <20110505191353.GB23311@elte.hu> (raw)
In-Reply-To: <alpine.DEB.2.00.1105051319230.6821@router.home>
* Christoph Lameter <cl@linux.com> wrote:
> On Thu, 5 May 2011, Tejun Heo wrote:
>
> > Anyways, that's what I've been thinking. I'll get to it in the next
> > devel cycle or the one after that. What do you guys think about soft
> > irq masking idea?
>
> Great idea. Would make the whole irq on/off business much cheaper.
The tradeoffs are *not at all* clear and the result (on x86) is not
'much cheaper', at all ...
In particular the irq-enable path gets complicated by the need to check the
flag and call a hardirq handling function in that case - a far cry from the
single-byte POPF instruction. It will be somewhat cheaper cycle-wise - but the
code gets bloated, so the instruction cache impact has to be measured
carefully. (See my other mail for details.)
There's also the fact that PUSHF+CLI+POPF sequence has been getting cheaper all
the time with newer hardware generations. CLI+STI is even cheaper, 10 cycles
both on Intel and AMD CPUs. So it's an optimization that might get narrower and
narrower with every CPU generation.
Thanks,
Ingo
next prev parent reply other threads:[~2011-05-05 19:14 UTC|newest]
Thread overview: 83+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-05-02 22:28 werner
2011-05-02 23:24 ` Linus Torvalds
[not found] ` <web-516990066@zbackend1.aha.ru>
2011-05-03 15:22 ` Linus Torvalds
2011-05-03 19:08 ` Ingo Molnar
2011-05-03 20:17 ` Linus Torvalds
2011-05-03 20:20 ` H. Peter Anvin
2011-05-03 20:50 ` Ingo Molnar
2011-05-03 21:45 ` Linus Torvalds
2011-05-03 22:01 ` H. Peter Anvin
2011-05-04 7:19 ` Borislav Petkov
2011-05-04 7:38 ` Ingo Molnar
2011-05-04 7:55 ` Borislav Petkov
2011-05-04 8:35 ` [block IO crash] " Ingo Molnar
2011-05-04 9:52 ` Thomas Gleixner
2011-05-04 10:19 ` Ingo Molnar
2011-05-04 10:25 ` Ingo Molnar
2011-05-04 10:33 ` Ingo Molnar
2011-05-04 12:37 ` Ingo Molnar
2011-05-04 12:36 ` Ingo Molnar
2011-05-04 11:11 ` Thomas Gleixner
2011-05-04 11:16 ` Pekka Enberg
2011-05-04 11:27 ` Tejun Heo
2011-05-04 12:51 ` Pekka Enberg
2011-05-04 12:57 ` Ingo Molnar
2011-05-04 13:02 ` Thomas Gleixner
2011-05-04 13:00 ` Thomas Gleixner
2011-05-04 13:20 ` Tejun Heo
2011-05-04 14:10 ` Thomas Gleixner
2011-05-04 14:14 ` Ingo Molnar
2011-05-04 14:36 ` [PATCH] slub: Fix the lockless code on 32-bit platforms with no 64-bit cmpxchg Ingo Molnar
2011-05-04 14:42 ` Christoph Lameter
2011-05-04 16:30 ` Ingo Molnar
2011-05-04 21:52 ` Ben Greear
2011-05-04 22:00 ` Linus Torvalds
2011-05-04 22:22 ` Ben Greear
2011-05-04 14:19 ` [block IO crash] Re: 2.6.39-rc5-git2 boot crashs Christoph Lameter
2011-05-04 14:25 ` Tejun Heo
2011-05-04 14:35 ` Christoph Lameter
2011-05-04 15:20 ` Ingo Molnar
2011-05-04 14:46 ` Thomas Gleixner
2011-05-04 15:00 ` Christoph Lameter
2011-05-04 15:13 ` Linus Torvalds
2011-05-04 15:28 ` Christoph Lameter
2011-05-04 15:37 ` Pekka Enberg
2011-05-04 15:53 ` Linus Torvalds
2011-05-04 18:20 ` Linus Torvalds
2011-05-04 18:49 ` Christoph Lameter
2011-05-04 19:07 ` Linus Torvalds
2011-05-04 19:30 ` Christoph Lameter
2011-05-04 19:38 ` Linus Torvalds
2011-05-04 20:04 ` Christoph Lameter
2011-05-04 20:21 ` Valdis.Kletnieks
2011-05-04 20:32 ` Christoph Lameter
2011-05-04 20:49 ` Ingo Molnar
2011-05-04 21:06 ` Linus Torvalds
2011-05-04 21:19 ` Linus Torvalds
2011-05-04 21:40 ` Thomas Gleixner
2011-05-05 9:54 ` Tejun Heo
2011-05-05 10:18 ` Ingo Molnar
2011-05-05 10:45 ` Thomas Gleixner
2011-05-05 18:20 ` Christoph Lameter
2011-05-05 19:13 ` Ingo Molnar [this message]
2011-05-05 19:53 ` werner
2011-05-05 20:09 ` Christoph Lameter
2011-05-05 21:12 ` werner
2011-05-05 22:27 ` Thomas Gleixner
[not found] ` <web-518008166@zbackend1.aha.ru>
[not found] ` <web-518059420@zbackend1.aha.ru>
[not found] ` <20110505060204.GA28015@elte.hu>
2011-05-05 6:46 ` werner
2011-05-04 15:37 ` [block IO crash] " Linus Torvalds
2011-05-04 16:08 ` Christoph Lameter
2011-05-04 16:50 ` Ingo Molnar
2011-05-04 17:12 ` Thomas Gleixner
2011-05-04 15:41 ` Pekka Enberg
2011-05-04 13:22 ` Ingo Molnar
2011-05-04 14:21 ` Christoph Lameter
2011-05-04 14:04 ` Christoph Lameter
2011-05-04 14:07 ` Tejun Heo
2011-05-04 14:21 ` Thomas Gleixner
2011-05-04 10:13 ` Ingo Molnar
2011-05-04 10:41 ` Ingo Molnar
2011-05-04 10:45 ` Ingo Molnar
2011-05-04 11:06 ` Ingo Molnar
2011-05-04 12:37 ` Ingo Molnar
2011-05-04 12:47 ` Ingo Molnar
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