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

From: Alex Shi
Date: Tue Dec 24 2013 - 22:30:55 EST

On 12/23/2013 01:24 PM, Fengguang Wu wrote:
> On Mon, Dec 23, 2013 at 01:19:04PM +0800, Alex Shi wrote:
>> On 12/22/2013 08:30 AM, fengguang.wu@xxxxxxxxx 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.

I don't know much of kvm. Where the data get from, VM guest or VM host?
Looks like any guest cpu usage will be counted as user usage in vmstat.
and Does the CS and cpu migration reducing cause dd performance increase?
>
> Thanks,
> Fengguang
>
>>>
>>> 6eb8b571283e64e96ca1a91aad085f9e08f857f0 is the first bad commit
>>> commit 6eb8b571283e64e96ca1a91aad085f9e08f857f0
>>> Author: Alex Shi <alex.shi@xxxxxxxxxx>
>>> 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@xxxxxxxxxx>
>>>
>>>
>>> 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


--
Thanks
Alex
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/