linux-kernel - Re: [PATCH tip/core/rcu] Reduce overhead of cond

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: <20140624003934.GR4603@linux.vnet.ibm.com>
Date:	Mon, 23 Jun 2014 17:39:34 -0700
From:	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
To:	Dave Hansen <dave.hansen@...el.com>
Cc:	linux-kernel@...r.kernel.org, mingo@...nel.org,
	laijs@...fujitsu.com, dipankar@...ibm.com,
	akpm@...ux-foundation.org, mathieu.desnoyers@...icios.com,
	josh@...htriplett.org, tglx@...utronix.de, peterz@...radead.org,
	rostedt@...dmis.org, dhowells@...hat.com, edumazet@...gle.com,
	dvhart@...ux.intel.com, fweisbec@...il.com, oleg@...hat.com,
	ak@...ux.intel.com, cl@...two.org, umgwanakikbuti@...il.com
Subject: Re: [PATCH tip/core/rcu] Reduce overhead of cond_resched() checks
 for RCU

On Mon, Jun 23, 2014 at 05:20:30PM -0700, Dave Hansen wrote:
> On 06/23/2014 05:15 PM, Paul E. McKenney wrote:
> > Just out of curiosity, how many CPUs does your system have?  80?
> > If 160, looks like something bad is happening at 80.
> 
> 80 cores, 160 threads.  >80 processes/threads is where we start using
> the second thread on the cores.  The tasks are also pinned to
> hyperthread pairs, so they disturb each other, and the scheduler moves
> them between threads on occasion which causes extra noise.

OK, that could explain the near flattening of throughput near 80
processes.  Is 3.16.0-rc1-pf2 with the two RCU patches?  If so, is the
new sysfs parameter at its default value?

							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/