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SubjectRe: [tip:sched/core] sched/balancing: Fix cfs_rq-> task_h_load calculation
On Fri, Sep 20, 2013 at 06:46:59AM -0700, tip-bot for Vladimir Davydov wrote:
> Commit-ID: 7e3115ef5149fc502e3a2e80719dba54a8e7409d
> Gitweb: http://git.kernel.org/tip/7e3115ef5149fc502e3a2e80719dba54a8e7409d
> Author: Vladimir Davydov <vdavydov@parallels.com>
> AuthorDate: Sat, 14 Sep 2013 19:39:46 +0400
> Committer: Ingo Molnar <mingo@kernel.org>
> CommitDate: Fri, 20 Sep 2013 11:59:39 +0200
>
> sched/balancing: Fix cfs_rq->task_h_load calculation
>
> Patch a003a2 (sched: Consider runnable load average in move_tasks())
> sets all top-level cfs_rqs' h_load to rq->avg.load_avg_contrib, which is
> always 0. This mistype leads to all tasks having weight 0 when load
> balancing in a cpu-cgroup enabled setup. There obviously should be sum
> of weights of all runnable tasks there instead. Fix it.

Hi Vladimir,

FYI, Here we found a 17% netperf regression by this patch. Here are some
changed stats between this commit 7e3115ef5149fc502e3a2e80719dba54a8e7409d
and it's parent(3029ede39373c368f402a76896600d85a4f7121b)

NOTE: both commit had been tested 10+ times.

stat 7e3115ef5149fc502e3a2e80719 3029ede39373c368f402a768966
netperf.Throughput_Mbps [ 2515 - 2593 ] -- [ 3010 - 3042 ]

lock_stat.&(&base->lock)->rlock.contentions.run_timer_softirq [ 188 - 261 ] -- [ 1907 - 2018 ]
lock_stat.&rq->lock.contentions [ 16885 - 23944 ] -- [ 2.6544e+05 - 2.8201e+05 ]
lock_stat.slock-AF_INET/1.contentions.release_sock [ 28993 - 34079 ] -- [ 2.6537e+05 - 2.7814e+05 ]
lock_stat.slock-AF_INET/1.contentions.tcp_v4_rcv [ 54906 - 64453 ] -- [ 4.6572e+05 - 4.8895e+05 ]
lock_stat.slock-AF_INET/1.contentions [ 54778 - 64265 ] -- [ 4.6503e+05 - 4.8831e+05 ]
lock_stat.slock-AF_INET/1.contentions.lock_sock_nested [ 25382 - 29998 ] -- [ 1.9822e+05 - 2.0934e+05 ]
lock_stat.slock-AF_INET.contentions.lock_sock_nested [ 1.5861e+05 - 1.8802e+05 ] -- [ 1.2317e+06 - 1.3016e+06 ]
lock_stat.slock-AF_INET.contentions.tcp_v4_rcv [ 1.9181e+05 - 2.2617e+05 ] -- [ 1.5482e+06 - 1.6346e+06 ]
lock_stat.slock-AF_INET.contentions [ 1.9259e+05 - 2.269e+05 ] -- [ 1.5536e+06 - 1.6403e+06 ]
lock_stat.&(&base->lock)->rlock.contentions [ 5658 - 9045 ] -- [ 1.3812e+05 - 1.478e+05 ]
lock_stat.&(&base->lock)->rlock.contentions.lock_timer_base [ 11006 - 17636 ] -- [ 2.7183e+05 - 2.9104e+05 ]
lock_stat.slock-AF_INET.contentions.release_sock [ 33931 - 39607 ] -- [ 3.2735e+05 - 3.4512e+05 ]
lock_stat.&(&base->lock)->rlock.contentions.mod_timer [ 93 - 152 ] -- [ 2347 - 2643 ]
lock_stat.&(&zone->lock)->rlock.contentions.__free_pages_ok [ 6.4647e+07 - 6.6226e+07 ] -- [ 5.3604e+07 - 5.5065e+07 ]
vmstat.system.in [ 8921 - 9414 ] -- [ 27103 - 28369 ]
vmstat.system.cs [ 1.4924e+05 - 1.9988e+05 ] -- [ 6.1384e+05 - 6.4036e+05 ]
lock_stat.&(&zone->lock)->rlock.contentions [ 6.7612e+07 - 6.9817e+07 ] -- [ 5.7419e+07 - 5.8889e+07 ]
lock_stat.rcu_node_1.contentions.rcu_process_callbacks [ 81543 - 87346 ] -- [ 97955 - 1.0295e+05 ]
iostat.cpu.user [ 1.4141 - 1.5051 ] -- [ 2.1044 - 2.1732 ]
lock_stat.&(&zone->lock)->rlock.contentions.get_page_from_freelist [ 7.0564e+07 - 7.3656e+07 ] -- [ 6.1222e+07 - 6.2746e+07 ]
lock_stat.&rq->lock.contentions.__schedule [ 8276 - 11422 ] -- [ 1.1656e+05 - 1.9275e+05 ]
iostat.cpu.system [ 95.387 - 95.516 ] -- [ 94.736 - 94.81 ]
vmstat.cpu.sy [ 96 - 96 ] -- [ 95 - 95 ]



And here are the text plot charts for those changed stats:

* for 7e3115ef5149fc502e3a2e80719dba54a8e7409d(this commit)
O for 3029ede39373c368f402a76896600d85a4f7121b(parent)

netperf.Throughput_Mbps

3100 ++------------------------------------------------------------------+
O O |
3000 ++ O O O O O O O O
| |
| |
2900 ++ |
| |
2800 ++ |
| |
2700 ++ |
| |
| |
2600 ++ ..*......*.......*......*.......*...... ....*
| .... *... |
2500 *+------*------*----------------------------------------------------+


vmstat.system.in

30000 ++-----------------------------------------------------------------+
28000 O+ O O O |
| O O O O O O
26000 ++ |
24000 ++ |
22000 ++ |
20000 ++ |
| |
18000 ++ |
16000 ++ |
14000 ++ |
12000 ++ |
| |
10000 *+.....*.......*......*.......*......*.......*......*.......*......*
8000 ++-----------------------------------------------------------------+


vmstat.system.cs

700000 ++----------------------------------------------------------------+
O O |
600000 ++ O O O O O O O O
| |
| |
500000 ++ |
| |
400000 ++ |
| |
300000 ++ |
| |
| ...*
200000 ++ ...*...... ....*...... ....*... |
*......*.......*... *... *......*... |
100000 ++----------------------------------------------------------------+


vmstat.cpu.sy

96 *+------*------*--------------*-------*------*-------*------*-------*
| : : |
| : : |
95.8 ++ : : |
| : : |
| : : |
95.6 ++ : : |
| : : |
95.4 ++ : : |
| : : |
| : : |
95.2 ++ : : |
| : : |
| : : |
95 O+------O------O-------*------O-------O------O-------O------O-------O


lock_stat.&(&zone->lock)->rlock.contentions

7.2e+07 ++---------------------------------------------------------------+
| |
7e+07 ++ ...*......*.......*......*...... ...*.......*..... |
6.8e+07 *+.. *... . |
| *......*
6.6e+07 ++ |
| |
6.4e+07 ++ |
| |
6.2e+07 ++ |
6e+07 ++ |
| O O
5.8e+07 ++ O O O O |
O O O |
5.6e+07 ++---------------------------O-----------------------------------+


lock_stat.&(&zone->lock)->rlock.contentions.get_page_from_freelist

7.4e+07 ++---------------------------*---------------------*-------------+
| ....*... . ...*... .. |
7.2e+07 *+.....*......*... *... . |
| *......*
7e+07 ++ |
| |
6.8e+07 ++ |
| |
6.6e+07 ++ |
| |
6.4e+07 ++ |
| O O O
6.2e+07 ++ O O O |
O O O |
6e+07 ++---------------------------O-----------------------------------+


lock_stat.&(&zone->lock)->rlock.contentions.__free_pages_ok

6.8e+07 ++---------------------------------------------------------------+
| ....*..... |
6.6e+07 *+.....*......*.......*......*......*......*... . |
6.4e+07 ++ *......*
| |
6.2e+07 ++ |
| |
6e+07 ++ |
| |
5.8e+07 ++ |
5.6e+07 ++ |
| O O O
5.4e+07 O+ O O O O |
| O O |
5.2e+07 ++---------------------------------------------------------------+


lock_stat.slock-AF_INET.contentions

1.8e+06 ++---------------------------------------------------------------+
O O O O |
1.6e+06 ++ O O O O O O
1.4e+06 ++ |
| |
1.2e+06 ++ |
1e+06 ++ |
| |
800000 ++ |
600000 ++ |
| |
400000 ++ |
200000 *+..... ....*......*......*......*....... ...*......*
| *......*... *... |
0 ++---------------------------------------------------------------+


lock_stat.slock-AF_INET.contentions.lock_sock_nested

1.4e+06 ++---------------------------------------------------------------+
O O O O |
1.2e+06 ++ O O O O O O
| |
1e+06 ++ |
| |
800000 ++ |
| |
600000 ++ |
| |
400000 ++ |
| |
200000 *+.....*......*.......*......*......*......*.......*......*......*
| |
0 ++---------------------------------------------------------------+


lock_stat.slock-AF_INET.contentions.release_sock

350000 O+-----O---------------------O--------------O---------------------+
| O O O O O O
300000 ++ |
| |
250000 ++ |
| |
200000 ++ |
| |
150000 ++ |
| |
100000 ++ |
| |
50000 ++ ...*...... ....*......*...... ....*......*
*......*.......*... *... *... |
0 ++----------------------------------------------------------------+


lock_stat.slock-AF_INET.contentions.tcp_v4_rcv

1.8e+06 ++---------------------------------------------------------------+
O O O O |
1.6e+06 ++ O O O O O O
1.4e+06 ++ |
| |
1.2e+06 ++ |
1e+06 ++ |
| |
800000 ++ |
600000 ++ |
| |
400000 ++ |
200000 *+..... ....*......*......*......*....... ...*......*
| *......*... *... |
0 ++---------------------------------------------------------------+


lock_stat.rcu_node_1.contentions.rcu_process_callbacks

110000 ++----------------------------------------------------------------+
| |
105000 ++ O |
| O |
O O O
100000 ++ O O O |
| O O |
95000 ++ |
| |
90000 ++ .*
| .... |
| .*.......*......*..... ..*. |
85000 ++.... . .*...... .... |
*. *....... .... *. |
80000 ++-----------------------------------*----------------------------+


lock_stat.slock-AF_INET/1.contentions

500000 ++---------------------------O--------------O---------------------+
O O O O O O O O
450000 ++ |
400000 ++ |
| |
350000 ++ |
300000 ++ |
| |
250000 ++ |
200000 ++ |
| |
150000 ++ |
100000 ++ |
| ....*...... |
50000 *+-----*-------*------*------*--------------*------*-------*------*


lock_stat.slock-AF_INET/1.contentions.tcp_v4_rcv

500000 ++---------------------------O--------------O---------------------+
O O O O O O O O
450000 ++ |
400000 ++ |
| |
350000 ++ |
300000 ++ |
| |
250000 ++ |
200000 ++ |
| |
150000 ++ |
100000 ++ |
| ....*...... |
50000 *+-----*-------*------*------*--------------*------*-------*------*


lock_stat.slock-AF_INET/1.contentions.release_sock

300000 ++----------------------------------------------------------------+
O O O O O |
250000 ++ O O O O O
| |
| |
200000 ++ |
| |
150000 ++ |
| |
100000 ++ |
| |
| |
50000 ++ ...*...... ....*......*...... ....*......*
*......*.......*... *... *... |
0 ++----------------------------------------------------------------+


lock_stat.slock-AF_INET/1.contentions.lock_sock_nested

220000 ++----------------------------------------------------------------+
200000 O+ O O O O O O O |
| O O
180000 ++ |
160000 ++ |
| |
140000 ++ |
120000 ++ |
100000 ++ |
| |
80000 ++ |
60000 ++ |
| |
40000 ++ ...*...... ....*......*...... ....*......*
20000 *+-----*-------*-------------*---------------------*--------------+


lock_stat.&rq->lock.contentions

300000 O+----------------------------------------------------------------+
| O O O O O |
250000 ++ O O O O
| |
| |
200000 ++ |
| |
150000 ++ |
| |
100000 ++ |
| |
| |
50000 ++ |
*......*.......*......*......*.......*......*......*.......*......*
0 ++----------------------------------------------------------------+


lock_stat.&rq->lock.contentions.__schedule

200000 O+----------------------------------------------------------------+
180000 ++ O O O O O O
| |
160000 ++ |
140000 ++ |
| O |
120000 ++ O O |
100000 ++ |
80000 ++ |
| |
60000 ++ |
40000 ++ |
| |
20000 *+.....*.......*......*......*.......*......*......*.......*......*
0 ++----------------------------------------------------------------+


lock_stat.&(&base->lock)->rlock.contentions

160000 ++----------------------------------------------------------------+
O O O O O
140000 ++ O O O O O |
120000 ++ |
| |
100000 ++ |
| |
80000 ++ |
| |
60000 ++ |
40000 ++ |
| |
20000 ++ |
*...... ...*......*.......*......*......*.......*......*
0 ++-----*-------*--------------------------------------------------+


lock_stat.&(&base->lock)->rlock.contentions.lock_timer_base

300000 O+-----O---------------------O------------------------------------+
| O O O O O O O
250000 ++ |
| |
| |
200000 ++ |
| |
150000 ++ |
| |
100000 ++ |
| |
| |
50000 ++ |
*......*.......*......*......*.......*......*......*.......*......*
0 ++----------------------------------------------------------------+


lock_stat.&(&base->lock)->rlock.contentions.run_timer_softirq

2200 ++------------------------------------------------------------------+
2000 O+ O O O |
| O O O O O O
1800 ++ |
1600 ++ |
1400 ++ |
1200 ++ |
| |
1000 ++ |
800 ++ |
600 ++ |
400 ++ |
| ....*...... ....*......*....... ...*.......|
200 *+......*......*... *... *... *
0 ++------------------------------------------------------------------+


lock_stat.&(&base->lock)->rlock.contentions.mod_timer

3000 ++------------------------------------------------------------------+
| |
2500 O+ O O O O O
| O O O |
| |
2000 ++ |
| |
1500 ++ |
| O |
1000 ++ |
| |
| |
500 ++ |
*....... ....*......*.......*......*.......*......*.......*
0 ++------*------*----------------------------------------------------+


iostat.cpu.user

2.2 O+--------------------------------------------O----------------------+
| O O O O O O O |
2.1 ++ O
2 ++ |
| |
1.9 ++ |
1.8 ++ |
| |
1.7 ++ |
1.6 ++ |
| |
1.5 ++ ....*......*....... ...*.......*
1.4 *+......*...... ....*... *.......*... |
| *... |
1.3 ++-------------------------------------------------------------------+


iostat.cpu.system

95.6 ++------------------------------------------------------------------+
*....... ...*.......*..... ....*..... |
95.5 ++ *... . ...*... . |
95.4 ++ *.......*... *.......*
| |
95.3 ++ |
95.2 ++ |
| |
95.1 ++ |
95 ++ |
| |
94.9 ++ |
94.8 ++ O O O
O O O O O O O |
94.7 ++------------------------------------------------------------------+


And here is the bisect log:
# bad: [e9a5cecac4145ba4a64827ac55728d33f5c8bb79] Merge 'drm/drm-fixes' into devel-hourly-2013092910
# good: [272b98c6455f00884f0350f775c5342358ebb73f] Linux 3.12-rc1
git bisect start 'e9a5cecac4145ba4a64827ac55728d33f5c8bb79' '272b98c6455f00884f0350f775c5342358ebb73f' '--'
# bad: [654fdd041227d7de1594baa61c58f2c87bd0640f] Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
git bisect bad 654fdd041227d7de1594baa61c58f2c87bd0640f
# good: [b75ff5e84bb6c2d43a8ec39b240c80f0543821f0] Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net
git bisect good b75ff5e84bb6c2d43a8ec39b240c80f0543821f0
# good: [d8524ae9d6f492a9c6db9f4d89c5f9b8782fa2d5] Merge branch 'drm-fixes' of git://people.freedesktop.org/~airlied/linux
git bisect good d8524ae9d6f492a9c6db9f4d89c5f9b8782fa2d5
# good: [4a10c2ac2f368583138b774ca41fac4207911983] Linux 3.12-rc2
git bisect good 4a10c2ac2f368583138b774ca41fac4207911983
# good: [a153e67bda3639a46edac6205610ae63c0fdea4c] Merge branch 'akpm' (patches from Andrew Morton)
git bisect good a153e67bda3639a46edac6205610ae63c0fdea4c
# good: [fa7315871046b9a4c48627905691dbde57e51033] perf: Fix capabilities bitfield compatibility in 'struct perf_event_mmap_page'
git bisect good fa7315871046b9a4c48627905691dbde57e51033
# bad: [82dfaa58a79c121be3611ce549dec806f2e6004f] Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
git bisect bad 82dfaa58a79c121be3611ce549dec806f2e6004f
# good: [bdc5663fa14de657f24080ee959670d49c8dd094] Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
git bisect good bdc5663fa14de657f24080ee959670d49c8dd094
# good: [3029ede39373c368f402a76896600d85a4f7121b] sched/balancing: Fix 'local->avg_load > busiest->avg_load' case in fix_small_imbalance()
git bisect good 3029ede39373c368f402a76896600d85a4f7121b
# bad: [7e3115ef5149fc502e3a2e80719dba54a8e7409d] sched/balancing: Fix cfs_rq->task_h_load calculation
git bisect bad 7e3115ef5149fc502e3a2e80719dba54a8e7409d
# first bad commit: [7e3115ef5149fc502e3a2e80719dba54a8e7409d] sched/balancing: Fix cfs_rq->task_h_load calculation

Please feel free to ask more data.

Thanks.

--yliu
>
> Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
> Reviewed-by: Paul Turner <pjt@google.com>
> Signed-off-by: Peter Zijlstra <peterz@infradead.org>
> Link: http://lkml.kernel.org/r/1379173186-11944-1-git-send-email-vdavydov@parallels.com
> Signed-off-by: Ingo Molnar <mingo@kernel.org>
> ---
> kernel/sched/fair.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index 2aedacc..7c70201 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -4242,7 +4242,7 @@ static void update_cfs_rq_h_load(struct cfs_rq *cfs_rq)
> }
>
> if (!se) {
> - cfs_rq->h_load = rq->avg.load_avg_contrib;
> + cfs_rq->h_load = cfs_rq->runnable_load_avg;
> cfs_rq->last_h_load_update = now;
> }
>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
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