linux-kernel - Re: [PATCH] rcu: Only pin GP kthread when full dynticks is actually used

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: <20140613162130.GP6635@localhost.localdomain>
Date:	Fri, 13 Jun 2014 18:21:32 +0200
From:	Frederic Weisbecker <fweisbec@...il.com>
To:	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	Josh Triplett <josh@...htriplett.org>,
	Steven Rostedt <rostedt@...dmis.org>,
	Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
Subject: Re: [PATCH] rcu: Only pin GP kthread when full dynticks is actually
 used

On Fri, Jun 13, 2014 at 09:16:30AM -0700, Paul E. McKenney wrote:
> > Is it because we have dynticks CPUs staying too long in the kernel without
> > taking any quiescent states? Are we perhaps missing some rcu_user_enter() or
> > things?
> 
> Sort of the former, but combined with the fact that in-kernel CPUs still
> need scheduling-clock interrupts for RCU to make progress.  I could
> move this to RCU's context-switch hook, but that could be very bad for
> workloads that do lots of context switching.

Or I can restart the tick if the CPU stays in the kernel for too long without
a tick. I think that's what we were doing before but we removed that because
we never implemented it correctly (we sent scheduler IPI that did nothing...)
--
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/