Re: [patch v3 0/8] sched: use runnable avg in load balance

From: Michael Wang <wangyun@linux.vnet.ibm.com>
To: Alex Shi <alex.shi@intel.com>
Cc: mingo@redhat.com, peterz@infradead.org, tglx@linutronix.de,
	akpm@linux-foundation.org, arjan@linux.intel.com, bp@alien8.de,
	pjt@google.com, namhyung@kernel.org, efault@gmx.de,
	morten.rasmussen@arm.com, vincent.guittot@linaro.org,
	gregkh@linuxfoundation.org, preeti@linux.vnet.ibm.com,
	viresh.kumar@linaro.org, linux-kernel@vger.kernel.org,
	len.brown@intel.com, rafael.j.wysocki@intel.com, jkosina@suse.cz,
	clark.williams@gmail.com, tony.luck@intel.com,
	keescook@chromium.org, mgorman@suse.de, riel@redhat.com
Subject: Re: [patch v3 0/8] sched: use runnable avg in load balance
Date: Tue, 02 Apr 2013 15:23:39 +0800	[thread overview]
Message-ID: <515A877B.3020908@linux.vnet.ibm.com> (raw)
In-Reply-To: <1364873008-3169-1-git-send-email-alex.shi@intel.com>

On 04/02/2013 11:23 AM, Alex Shi wrote:
[snip]
> 
> [patch v3 1/8] Revert "sched: Introduce temporary FAIR_GROUP_SCHED
> [patch v3 2/8] sched: set initial value of runnable avg for new
> [patch v3 3/8] sched: only count runnable avg on cfs_rq's nr_running
> [patch v3 4/8] sched: update cpu load after task_tick.
> [patch v3 5/8] sched: compute runnable load avg in cpu_load and
> [patch v3 6/8] sched: consider runnable load average in move_tasks
> [patch v3 7/8] sched: consider runnable load average in
> [patch v3 8/8] sched: use instant load for burst wake up

I've tested the patch set on 12 cpu X86 box with 3.9.0-rc2, and pgbench
show regression on high-end this time.

| db_size | clients |  tps  |   |  tps  |
+---------+---------+-------+   +-------+
| 22 MB   |       1 | 10662 |   | 10446 |
| 22 MB   |       2 | 21483 |   | 20887 |
| 22 MB   |       4 | 42046 |   | 41266 |
| 22 MB   |       8 | 55807 |   | 51987 |
| 22 MB   |      12 | 50768 |   | 50974 |
| 22 MB   |      16 | 49880 |   | 49510 |
| 22 MB   |      24 | 45904 |   | 42398 |
| 22 MB   |      32 | 43420 |   | 40995 |
| 7484 MB |       1 |  7965 |   |  7376 |
| 7484 MB |       2 | 19354 |   | 19149 |
| 7484 MB |       4 | 37552 |   | 37458 |
| 7484 MB |       8 | 48655 |   | 46618 |
| 7484 MB |      12 | 45778 |   | 45756 |
| 7484 MB |      16 | 45659 |   | 44911 |
| 7484 MB |      24 | 42192 |   | 37185 |	-11.87%
| 7484 MB |      32 | 36385 |   | 34447 |
| 15 GB   |       1 |  7677 |   |  7359 |
| 15 GB   |       2 | 19227 |   | 19049 |
| 15 GB   |       4 | 37335 |   | 36947 |
| 15 GB   |       8 | 48130 |   | 46898 |
| 15 GB   |      12 | 45393 |   | 43986 |
| 15 GB   |      16 | 45110 |   | 45719 |
| 15 GB   |      24 | 41415 |   | 36813 |	-11.11%
| 15 GB   |      32 | 35988 |   | 34025 |

The reason may caused by wake_affine()'s higher overhead, and pgbench is
really sensitive to this stuff...

Regards,
Michael Wang

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