From: Thomas Gleixner <tglx@linutronix.de>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Sabrina Dubroca <sd@queasysnail.net>,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
jeffrey.t.kirsher@intel.com
Subject: Re: e1000_netpoll(): disable_irq() triggers might_sleep() on linux-next
Date: Wed, 29 Oct 2014 22:03:20 +0100 (CET) [thread overview]
Message-ID: <alpine.DEB.2.11.1410292201530.5308@nanos> (raw)
In-Reply-To: <20141029205131.GI10501@worktop.programming.kicks-ass.net>
On Wed, 29 Oct 2014, Peter Zijlstra wrote:
> On Wed, Oct 29, 2014 at 09:23:42PM +0100, Thomas Gleixner wrote:
> > But at least it allows to mitigate the impact by making it conditional
> > at a central point.
> >
> > static inline void netpoll_lock(struct net_device *nd)
> > {
> > if (netpoll_active(nd))
> > spin_lock(&nd->netpoll_lock);
> > }
>
> branch fail vs lock might be a toss on most machines, but if we're
> hitting cold cachelines we loose big.
Well, if the net_device is not cache hot on irq entry you have lost
already. The extra branch/lock is not going to add much to that.
Thanks,
tglx
next prev parent reply other threads:[~2014-10-29 21:03 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-10-29 15:56 e1000_netpoll(): disable_irq() triggers might_sleep() on linux-next Sabrina Dubroca
2014-10-29 18:07 ` Peter Zijlstra
2014-10-29 18:33 ` Thomas Gleixner
2014-10-29 19:36 ` Peter Zijlstra
2014-10-29 19:40 ` Jeff Kirsher
2014-10-29 19:53 ` Thomas Gleixner
2014-10-29 19:49 ` Thomas Gleixner
2014-10-29 19:50 ` Peter Zijlstra
2014-10-29 20:07 ` Thomas Gleixner
2014-10-29 20:23 ` Thomas Gleixner
2014-10-29 20:51 ` Peter Zijlstra
2014-10-29 21:03 ` Thomas Gleixner [this message]
2014-12-02 16:35 ` Sabrina Dubroca
2014-12-22 15:28 ` Bart Van Assche
2015-01-05 10:06 ` Bart Van Assche
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=alpine.DEB.2.11.1410292201530.5308@nanos \
--to=tglx@linutronix.de \
--cc=jeffrey.t.kirsher@intel.com \
--cc=linux-kernel@vger.kernel.org \
--cc=netdev@vger.kernel.org \
--cc=peterz@infradead.org \
--cc=sd@queasysnail.net \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox