[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date: Thu, 4 Apr 2013 18:10:14 +0000
From: Christoph Lameter <cl@...ux.com>
To: Frederic Weisbecker <fweisbec@...il.com>
cc: Ingo Molnar <mingo@...nel.org>,
LKML <linux-kernel@...r.kernel.org>,
Andrew Morton <akpm@...ux-foundation.org>,
Chris Metcalf <cmetcalf@...era.com>,
Geoff Levand <geoff@...radead.org>,
Gilad Ben Yossef <gilad@...yossef.com>,
Hakan Akkan <hakanakkan@...il.com>,
Kevin Hilman <khilman@...aro.org>,
Li Zhong <zhong@...ux.vnet.ibm.com>,
Namhyung Kim <namhyung.kim@....com>,
"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
Paul Gortmaker <paul.gortmaker@...driver.com>,
Peter Zijlstra <peterz@...radead.org>,
Steven Rostedt <rostedt@...dmis.org>,
Thomas Gleixner <tglx@...utronix.de>,
Michal Marek <mmarek@...e.cz>
Subject: Re: [RFC GIT PULL] nohz: Kconfig layout improvements
It seems that nohz still has no effect.
3.9-rc5 + patches. Affinity of init set to 0,1 so no
tasks are running on 9. The "latencytest" used here is part of my
lldiag-0.15 toolkit.
First test without any special kernel parameters. nohz off right?
$ nice -5 taskset -c 9 latencytest
CPUs: Freq=2.90Ghz Processors=32 Cores=8 cacheline_size=64 Intel(R)
Xeon(R) CPU E5-2690 0 @ 2.90GHz
16775106 samples below 1000 nsec
13 involuntary context switches
1019 (0.00607411%) variances in 10.00 seconds: minimum 1.07us maximum 12.32us average 3.30us stddev 0.63us
HZ=100 so the 1019 variances are likely timer interrupts.
After nohz setup
/proc/cmdline:
BOOT_IMAGE=/vmlinuz-3.9.0-rc5+ root=/dev/mapper/vg01-root ro console=tty0 console=ttyS0,115200 idle=mwait rcu_nocb_poll rcu_nocbs=2-31 nohz_extended=2-31
$ nice -5 taskset -c 9 latencytest
CPUs: Freq=2.90Ghz Processors=32 Cores=8 cacheline_size=64 Intel(R)
Xeon(R) CPU E5-2690 0 @ 2.90GHz
16779362 samples below 1000 nsec
13 involuntary context switches
1037 (0.00617983%) variances in 10.00 seconds: minimum 1.00us maximum 10.61us average 3.30us stddev 0.98us
If I move the RCU threads off the cpu then I get a slightly better result:
$ nice -5 taskset -c 9 latencytest
CPUs: Freq=2.90Ghz Processors=32 Cores=8 cacheline_size=64 Intel(R)
Xeon(R) CPU E5-2690 0 @ 2.90GHz
16796039 samples below 1000 nsec
12 involuntary context switches
1020 (0.00607249%) variances in 10.00 seconds: minimum 1.00us maximum 11.58us average 2.77us stddev 0.55us
Why is the tick not stopping? How do I diagnose this? (I can start
patching the kernel again like last time but isnt there a better way?)
--
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