Re: [sched] perf-stat.cpu-migrations changes in dd write test

Fengguang Wu
2013-12-23T05:24:45Z

On Mon, Dec 23, 2013 at 01:19:04PM +0800, Alex Shi wrote:
> On 12/22/2013 08:30 AM, fengguang.wu@intel.com wrote:
> > Alex,
> >
> > We noticed some perf-stat.cpu-migrations changes by your commit
>
> Thanks for your wonder testing, Fengguang!
> How many CPU in your system and how many dd task running?

For the case

kbuildx/micro/dd-write/4HDD-JBOD-cfq-ext4-10dd

It's a KVM with 4 CPUs, 16G memory. There are 4 virtual disks, on top
of each disk there runs 10 dd tasks.

Thanks,
Fengguang

> >
> > 6eb8b571283e64e96ca1a91aad085f9e08f857f0 is the first bad commit
> > commit 6eb8b571283e64e96ca1a91aad085f9e08f857f0
> > Author: Alex Shi <alex.shi@linaro.org>
> > Date: Tue Nov 19 20:29:51 2013 +0800
> >
> > sched: remove rq->cpu_load[load_idx] array
> >
> > Since load_idx effect removed in load balance, we don't need the
> > load_idx decays in scheduler. that will save some process in sched_tick
> > and others places.
> >
> > Signed-off-by: Alex Shi <alex.shi@linaro.org>
> >
> >
> > Here are the changed stats comparing to its parent commit:
> >
> > 1de157d718f6494 6eb8b571283e64e96ca1
> > --------------- -------------------------
> > 37779 ~40% +115.2% 81288 ~50% kbuildx/micro/dd-write/4HDD-JBOD-cfq-ext4-10dd
> > 37779 +115.2% 81288 TOTAL proc-vmstat.pgscan_direct_normal
> >
> > kbuildx/micro/dd-write/4HDD-JBOD-cfq-ext4-10dd: proc-vmstat.pgscan_direct_normal
> >
> > 160000 ++----------------------------------------------------------------+
> > | |
> > 140000 ++ O
> > | |
> > 120000 ++ |
> > | O |
> > 100000 ++ |
> > | |
> > 80000 ++ O |
> > | ..*
> > 60000 ++ .... |
> > | .... |
> > 40000 *+............... O .... |
> > O *............... ........*. |
> > 20000 ++-------------------------------*--------------------------------+
> >
> >
> > 1de157d718f6494 6eb8b571283e64e96ca1
> > --------------- -------------------------
> > 121579 ~ 6% -50.8% 59852 ~13% kbuildx/micro/dd-write/4HDD-JBOD-cfq-ext4-10dd
> > 121579 -50.8% 59852 TOTAL softirqs.SCHED
> >
> > kbuildx/micro/dd-write/4HDD-JBOD-cfq-ext4-10dd: softirqs.SCHED
> >
> > 140000 ++----------------------------------------------------------------+
> > 130000 ++ ....*........... ....*....... |
> > | ........ .... ........ ...... |
> > 120000 *+... *.... ..|
> > 110000 ++ *
> > | |
> > 100000 ++ |
> > 90000 ++ |
> > 80000 ++ |
> > | |
> > 70000 ++ O O |
> > 60000 ++ O |
> > | O
> > 50000 O+ |
> > 40000 ++----------------------------------------------------------------+
> >
> >
> > 1de157d718f6494 6eb8b571283e64e96ca1
> > --------------- -------------------------
> > 5636 ~ 4% -22.1% 4392 ~17% kbuildx/micro/dd-write/4HDD-JBOD-cfq-ext4-10dd
> > 5636 -22.1% 4392 TOTAL proc-vmstat.nr_tlb_remote_flush
> >
> > kbuildx/micro/dd-write/4HDD-JBOD-cfq-ext4-10dd: proc-vmstat.nr_tlb_remote_flush
> >
> > 6500 ++------------------------------------------------------------------+
> > | |
> > 6000 ++ ........*............ |
> > *........ .... |
> > 5500 ++ O *................*................|
> > | *
> > 5000 ++ O |
> > | |
> > 4500 ++ O |
> > | |
> > 4000 ++ |
> > | O
> > 3500 O+ |
> > | |
> > 3000 ++------------------------------------------------------------------+
> >
> >
> > 1de157d718f6494 6eb8b571283e64e96ca1
> > --------------- -------------------------
> > 5679 ~ 4% -21.9% 4437 ~17% kbuildx/micro/dd-write/4HDD-JBOD-cfq-ext4-10dd
> > 5679 -21.9% 4437 TOTAL proc-vmstat.nr_tlb_remote_flush_received
> >
> >
> >
> > 6500 ++------------------------------------------------------------------+
> > | |
> > 6000 ++ ........*........ |
> > *........ ...... |
> > | .. ........*................|
> > 5500 ++ O *........ *
> > | |
> > 5000 ++ O |
> > | |
> > 4500 ++ O |
> > | |
> > | |
> > 4000 ++ |
> > | O
> > 3500 O+------------------------------------------------------------------+
> >
> >
> > 1de157d718f6494 6eb8b571283e64e96ca1
> > --------------- -------------------------
> > 167 ~11% +19.4% 200 ~ 4% kbuildx/micro/dd-write/4HDD-JBOD-cfq-ext4-10dd
> > 167 +19.4% 200 TOTAL uptime.idle
> >
> > kbuildx/micro/dd-write/4HDD-JBOD-cfq-ext4-10dd: uptime.idle
> >
> > 220 ++-------------------------------------------------------------------+
> > | O
> > 210 ++ |
> > 200 O+ O |
> > | ..*..... O |
> > 190 ++ .... O ... |
> > 180 ++ .... .... |
> > | .... .... |
> > 170 *+. . .*
> > 160 ++ *...... .... |
> > | .... ... |
> > 150 ++ .... ... |
> > 140 ++ .. .... |
> > | *. |
> > 130 ++-------------------------------------------------------------------+
> >
> >
> > 1de157d718f6494 6eb8b571283e64e96ca1
> > --------------- -------------------------
> > 154781 ~ 5% -66.8% 51449 ~ 8% kbuildx/micro/dd-write/4HDD-JBOD-cfq-ext4-10dd
> > 154781 -66.8% 51449 TOTAL perf-stat.cpu-migrations
> >
> > kbuildx/micro/dd-write/4HDD-JBOD-cfq-ext4-10dd: perf-stat.cpu-migrations
> >
> > 180000 ++----------------------------------------------------------------+
> > | ....*........... |
> > 160000 ++ ........ .... ........*...............|
> > *.... *........ *
> > 140000 ++ |
> > | |
> > 120000 ++ |
> > | |
> > 100000 ++ |
> > | |
> > 80000 ++ |
> > | |
> > 60000 ++ O |
> > | O O O
> > 40000 O+----------------------------------------------------------------+
> >
> >
> > 1de157d718f6494 6eb8b571283e64e96ca1
> > --------------- -------------------------
> > 1943 ~ 3% -7.8% 1792 ~ 4% kbuildx/micro/dd-write/4HDD-JBOD-cfq-ext4-10dd
> > 1943 -7.8% 1792 TOTAL vmstat.system.cs
> >
> > kbuildx/micro/dd-write/4HDD-JBOD-cfq-ext4-10dd: vmstat.system.cs
> >
> > 2050 ++------------------------------------------------------------------+
> > | ........*................*..... |
> > 2000 ++ .*........ ... |
> > 1950 ++ .... ... |
> > | ... .... |
> > 1900 ++ ... .|
> > 1850 ++.... O O *
> > *. |
> > 1800 ++ O O
> > 1750 ++ |
> > | |
> > 1700 ++ |
> > 1650 O+ |
> > | |
> > 1600 ++------------------------------------------------------------------+
> >
> >
> > 1de157d718f6494 6eb8b571283e64e96ca1
> > --------------- -------------------------
> > 1216177 ~ 3% -9.4% 1101605 ~ 7% kbuildx/micro/dd-write/4HDD-JBOD-cfq-ext4-10dd
> > 1216177 -9.4% 1101605 TOTAL perf-stat.context-switches
> >
> > kbuildx/micro/dd-write/4HDD-JBOD-cfq-ext4-10dd: perf-stat.context-switches
> >
> > 1.3e+06 ++--------------------------------------------------------------+
> > | ..*............... |
> > 1.25e+06 ++ ...... *...............*....... |
> > | ..... ...... |
> > 1.2e+06 *+. O ..|
> > 1.15e+06 ++ O *
> > | O |
> > 1.1e+06 ++ |
> > | O
> > 1.05e+06 ++ |
> > 1e+06 ++ |
> > | |
> > 950000 O+ |
> > | |
> > 900000 ++--------------------------------------------------------------+
> >
> >
>
>
> --
> Thanks
> Alex