linux-kernel - Re: [PATCH v2 1/2] workqueue: add quiescent state between work items

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: <20141008032411.GG4880@linux.vnet.ibm.com>
Date:	Tue, 7 Oct 2014 20:24:11 -0700
From:	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
To:	Joe Lawrence <joe.lawrence@...atus.com>
Cc:	Jiri Pirko <jiri@...nulli.us>, Tejun Heo <tj@...nel.org>,
	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Subject: Re: [PATCH v2 1/2] workqueue: add quiescent state between work items

On Tue, Oct 07, 2014 at 01:45:28PM -0400, Joe Lawrence wrote:
> On Tue, 7 Oct 2014 06:43:29 -0700
> "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com> wrote:
> 
> > On Tue, Oct 07, 2014 at 09:29:42AM +0200, Jiri Pirko wrote:
> [ ... snip ... ]
> > > 
> > > Paul, Tehun, how do you propose to fix this on older kernels which do
> > > not have rcu_note_voluntary_context_switch? I'm particullary interested
> > > in 3.10.
> > 
> > Hello, Jiri,
> > 
> > Older kernels can instead use rcu_note_context_switch().
> 
> Hi Paul,
> 
> Does 4a81e8328d37 ("rcu: Reduce overhead of cond_resched() checks for
> RCU") affect a backport to 3.10?
> 
> I noticed that rcu_note_context_switch added a call to
> rcu_momentary_dyntick_idle in that change, which is only present in
> v3.16+.
> 
> Would rcu_note_context_switch be effective by itself on a 3.10 kernel?

Should be fine.  There is more overhead than current mainline, but that
should not be in the noise compared to executing a work-queue item.

							Thanx, Paul

--
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/