linux-kernel - Re: [bisected] pre-3.16 regression on open() scalability

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: <alpine.DEB.2.11.1406191612000.5484@gentwo.org>
Date:	Thu, 19 Jun 2014 16:13:12 -0500 (CDT)
From:	Christoph Lameter <cl@...two.org>
To:	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
cc:	Andi Kleen <ak@...ux.intel.com>,
	Dave Hansen <dave.hansen@...el.com>,
	LKML <linux-kernel@...r.kernel.org>,
	Josh Triplett <josh@...htriplett.org>,
	"Chen, Tim C" <tim.c.chen@...el.com>
Subject: Re: [bisected] pre-3.16 regression on open() scalability

On Thu, 19 Jun 2014, Paul E. McKenney wrote:

> On Thu, Jun 19, 2014 at 03:31:56PM -0500, Christoph Lameter wrote:
> > On Thu, 19 Jun 2014, Paul E. McKenney wrote:
> >
> > > That is a separate issue, but unnecessary calls to cond_resched()
> > > should of course be removed -- no argument there.
> >
> > It looks like we are fighting higher latencies by adding calls in most of
> > the critical sections which will in turn increase the latencies that we
> > are trying to reduce.
>
> That is on battle in a larger war.  Another battle is to keep big systems
> from choking and dying.  We need to win both battles, though I understand
> that you are focused primarily on latency reduction.  I don't get that
> luxury because RCU is used across the board.

At least reduce the increased latencies to a processor or put it somewhere
outside of the regular execution paths. Sprinkling this throughout the
kernel via a inline function that did not generate code in the non debug
situation before is not that nice.

--
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/