lists.openwall.net   lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  linux-cve-announce  PHC 
Open Source and information security mailing list archives
 
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <20150612123835.GA29736@lerouge>
Date:	Fri, 12 Jun 2015 14:38:36 +0200
From:	Frederic Weisbecker <fweisbec@...il.com>
To:	Peter Zijlstra <peterz@...radead.org>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Preeti U Murthy <preeti@...ux.vnet.ibm.com>,
	Christoph Lameter <cl@...ux.com>,
	Ingo Molnar <mingo@...nel.org>,
	Viresh Kumar <viresh.kumar@...aro.org>,
	Rik van Riel <riel@...hat.com>
Subject: Re: [PATCH 5/8] nohz: Restart the tick from irq exit

On Fri, Jun 12, 2015 at 09:32:45AM +0200, Peter Zijlstra wrote:
> On Thu, Jun 11, 2015 at 07:36:05PM +0200, Frederic Weisbecker wrote:
> > Restart the tick when necessary from the irq exit path. It makes nohz
> > full more flexible and allow it to piggyback the tick restart on the
> > scheduler IPI in the future instead of sending a dedicated IPI that
> > often doubles the scheduler IPI on task wakeup. This will require
> > careful review of resched_curr() callers.
> 
> This seems to assume schedule_ipi() callers use irq_exit(), this is
> false.

Indeed there will be that too. Note the current patch doesn't yet rely on
schedule_ipi(), we are still using the nohz ipis. But introducing the
tick restart on irq exit prepares for later piggybacking on scheduler_ipi().

I think this will involve changes on got_nohz_idle_kick(), renamed to
got_nohz_kick() and include nohz full related checks to trigger the
irq_enter()/exit() pair.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

Powered by blists - more mailing lists

Powered by Openwall GNU/*/Linux Powered by OpenVZ