linux-kernel - Re: 20% performance drop on PostgreSQL 9.2 from kernel 3.5.3 to 3.6-rc5 on AMD chipsets

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: <20120927192426.GF8527@x1.osrc.amd.com>
Date:	Thu, 27 Sep 2012 21:24:27 +0200
From:	Borislav Petkov <bp@...en8.de>
To:	Peter Zijlstra <a.p.zijlstra@...llo.nl>
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Ingo Molnar <mingo@...nel.org>, Mike Galbraith <efault@....de>,
	Mel Gorman <mgorman@...e.de>,
	Nikolay Ulyanitsky <lystor@...il.com>,
	linux-kernel@...r.kernel.org,
	Andreas Herrmann <andreas.herrmann3@....com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Suresh Siddha <suresh.b.siddha@...el.com>
Subject: Re: 20% performance drop on PostgreSQL 9.2 from kernel 3.5.3 to
 3.6-rc5 on AMD chipsets - bisected

On Thu, Sep 27, 2012 at 08:29:44PM +0200, Peter Zijlstra wrote:
> > >> Or could we just improve the heuristics. What happens if the
> > >> scheduling granularity is increased, for example? It's set to 1ms
> > >> right now, with a logarithmic scaling by number of cpus.
> > >
> > > /proc/sys/kernel/sched_wakeup_granularity_ns=10000000 (10ms)
> > > ------------------------------------------------------
> > > tps = 4994.730809 (including connections establishing)
> > > tps = 5000.260764 (excluding connections establishing)
> > >
> > > A bit better over the default NO_WAKEUP_PREEMPTION setting.
> > 
> > Ok, so this gives us something possible to actually play with.
> > 
> > For example, maybe SCHED_TUNABLESCALING_LINEAR is more appropriate
> > than SCHED_TUNABLESCALING_LOG. At least for WAKEUP_PREEMPTION. Hmm?
> 
> Don't forget to run the desktop interactivity benchmarks after you're
> done wriggling with this knob... wakeup preemption is important for most
> those.

Setting sched_tunable_scaling to SCHED_TUNABLESCALING_LINEAR made
wakeup_granularity go to 4ms:

sched_autogroup_enabled:1
sched_child_runs_first:0
sched_latency_ns:24000000
sched_migration_cost_ns:500000
sched_min_granularity_ns:3000000
sched_nr_migrate:32
sched_rt_period_us:1000000
sched_rt_runtime_us:950000
sched_shares_window_ns:10000000
sched_time_avg_ms:1000
sched_tunable_scaling:2
sched_wakeup_granularity_ns:4000000

pgbench results look good:

tps = 4997.675331 (including connections establishing)
tps = 5003.256870 (excluding connections establishing)

This is still with Ingo's NO_WAKEUP_PREEMPTION patch.

Thanks.

-- 
Regards/Gruss,
Boris.
--
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/