* High latency when running cyclictest
@ 2020-05-07 8:56 chen song
2020-05-12 10:56 ` chen song
0 siblings, 1 reply; 4+ messages in thread
From: chen song @ 2020-05-07 8:56 UTC (permalink / raw)
To: linux-rt-users
Dear experts,
I had a 4.14.4 kernel with its rtpatch running on a dual-core arm64
device, the desktop is ubuntu.
In general, the max latency of cyclictest is around 50us in empty load
which is acceptable. However, if i open a firefox duing cyclictest is
running, the max latency becomes higher up to 200us.
I tried to use ftrace to debug this issue,"cyclictest -p 90 -m -c 0 -i
10 -n -h 100 -q -l 10000000 -b 80", "-b 80" means enable ftrace event
and terminate cyclictest when latency is higher than 80us.
Here is a piece of log:
6034916919us+: cpu_idle: state=1 cpu_id=1
6034916981us+: hrtimer_cancel: hrtimer=ffffff8012663dc8
6034916994us+: sched_waking: comm=cyclictest pid=2321 prio=9 target_cpu=001
6034917032us+: cpu_idle: state=4294967295 cpu_id=1
6034917044us+: hrtimer_start: hrtimer=ffffffc07ffd5960
function=tick_sched_timer expires=6034920000000
softexpires=6034920000000 mode=ABS|PINNED
6034917066us+: sys_clock_nanosleep -> 0x0
In this case, I can only see it's stalled in some points but i could'n
find what happens, in other words, the root cause of the latency.
Is there any better way to debug this issue? I guess some of you might
meet the same issue, how did you approach to the root cause? I would
appreciate it so much if you could give me some advice, many thanks.
Best regards,
/Song
============================================================
Here is the log for reference:
<idle>-0 1d..h1.. 6034916878us : irq_handler_entry: irq=3
name=arch_timer -- this is a normal routine
<idle>-0 1d..h2.. 6034916879us : hrtimer_cancel:
hrtimer=ffffff8012663dc8
<idle>-0 1d..h1.. 6034916879us : hrtimer_expire_entry:
hrtimer=ffffff8012663dc8 function=hrtimer_wakeup now=6034916525493
<idle>-0 1d..h2.. 6034916880us : sched_waking: comm=cyclictest
pid=2321 prio=9 target_cpu=001
<idle>-0 1dn.h3.. 6034916882us : sched_wakeup: comm=cyclictest
pid=2321 prio=9 target_cpu=001
<idle>-0 1dn.h1.. 6034916883us : hrtimer_expire_exit:
hrtimer=ffffff8012663dc8
<idle>-0 1dn.h1.. 6034916884us : irq_handler_exit: irq=3
ret=handled
<idle>-0 1.n..1.. 6034916886us : cpu_idle: state=4294967295
cpu_id=1
<idle>-0 1dn..2.. 6034916888us : hrtimer_cancel:
hrtimer=ffffffc07ffd5960
<idle>-0 1dn..2.. 6034916890us : hrtimer_start:
hrtimer=ffffffc07ffd5960 function=tick_sched_timer expires=6034920000000
softexpires=6034920000000 mode=ABS|PINNED
<idle>-0 1dn..1.. 6034916891us : rcu_utilization: Start context
switch
<idle>-0 1dn..1.. 6034916892us : rcu_utilization: End context
switch
<idle>-0 1d...2.. 6034916894us : sched_switch:
prev_comm=swapper/1 prev_pid=0 prev_prio=120 prev_state=R ==>
next_comm=cyclictest next_pid=2321 next_prio=9
cyclicte-2321 1....... 6034916897us : kfree:
call_site=ffffff80081501f0 ptr= (null)
cyclicte-2321 1....... 6034916898us : sys_exit: NR 115 = 0
cyclicte-2321 1....1.. 6034916898us : sys_clock_nanosleep -> 0x0
cyclicte-2321 1....... 6034916902us : sys_enter: NR 115 (1, 1,
7fbd20b448, 0, 0, 7fbd20be00)
cyclicte-2321 1....1.. 6034916903us :
sys_clock_nanosleep(which_clock: 1, flags: 1, rqtp: 7fbd20b448, rmtp: 0)
cyclicte-2321 1....... 6034916904us : hrtimer_init:
hrtimer=ffffff8012663dc8 clockid=CLOCK_MONOTONIC mode=ABS
cyclicte-2321 1d...1.. 6034916906us : hrtimer_start:
hrtimer=ffffff8012663dc8 function=hrtimer_wakeup expires=6034916622448
softexpires=6034916622448 mode=ABS
cyclicte-2321 1d...1.. 6034916907us : rcu_utilization: Start context
switch
cyclicte-2321 1d...1.. 6034916908us : rcu_utilization: End context switch
cyclicte-2321 1d...2.. 6034916911us : sched_switch:
prev_comm=cyclictest prev_pid=2321 prev_prio=9 prev_state=S ==>
next_comm=swapper/1 next_pid=0 next_prio=120
<idle>-0 1d...1.. 6034916915us : tick_stop: success=1
dependency=NONE
<idle>-0 1d...2.. 6034916916us : hrtimer_cancel:
hrtimer=ffffffc07ffd5960
<idle>-0 1d...2.. 6034916917us : hrtimer_start:
hrtimer=ffffffc07ffd5960 function=tick_sched_timer expires=6035010000000
softexpires=6035010000000 mode=ABS|PINNED
<idle>-0 1d...1.. 6034916919us+: cpu_idle: state=1 cpu_id=1
--(1)
<idle>-0 1d..h1.. 6034916977us : irq_handler_entry: irq=3
name=arch_timer
<idle>-0 1d..h2.. 6034916981us+: hrtimer_cancel:
hrtimer=ffffff8012663dc8 --(2)
<idle>-0 1d..h1.. 6034916993us : hrtimer_expire_entry:
hrtimer=ffffff8012663dc8 function=hrtimer_wakeup now=6034916628193
<idle>-0 1d..h2.. 6034916994us+: sched_waking: comm=cyclictest
pid=2321 prio=9 target_cpu=001 --(3)
<idle>-0 1dn.h3.. 6034917016us : sched_wakeup: comm=cyclictest
pid=2321 prio=9 target_cpu=001
<idle>-0 1dn.h1.. 6034917016us : hrtimer_expire_exit:
hrtimer=ffffff8012663dc8
<idle>-0 1dn.h1.. 6034917026us : irq_handler_exit: irq=3
ret=handled
<idle>-0 1.n..1.. 6034917032us+: cpu_idle: state=4294967295
cpu_id=1 --(4)
<idle>-0 1dn..2.. 6034917043us : hrtimer_cancel:
hrtimer=ffffffc07ffd5960
<idle>-0 1dn..2.. 6034917044us+: hrtimer_start:
hrtimer=ffffffc07ffd5960 function=tick_sched_timer expires=6034920000000
softexpires=6034920000000 mode=ABS|PINNED --(5)
<idle>-0 1dn..1.. 6034917056us : rcu_utilization: Start context
switch
<idle>-0 1dn..1.. 6034917057us : rcu_utilization: End context
switch
<idle>-0 1d...2.. 6034917062us : sched_switch:
prev_comm=swapper/1 prev_pid=0 prev_prio=120 prev_state=R ==>
next_comm=cyclictest next_pid=2321 next_prio=9
cyclicte-2321 1....... 6034917065us : kfree:
call_site=ffffff80081501f0 ptr= (null)
cyclicte-2321 1....... 6034917066us : sys_exit: NR 115 = 0
cyclicte-2321 1....1.. 6034917066us+: sys_clock_nanosleep -> 0x0
--(5)
cyclicte-2321 1....... 6034917142us : sys_enter: NR 64 (5,
7fbd20c500, 1f, 7fbd20bf08, 2, 7fbd20be00)
cyclicte-2321 1....1.. 6034917143us : sys_write(fd: 5, buf:
7fbd20c500, count: 1f)
cyclicte-2321 1....... 6034917151us : tracing_mark_write: hit latency
threshold (91 > 80)
cyclicte-2321 1....... 6034917155us : kfree:
call_site=ffffff80081501f0 ptr= (null)
cyclicte-2321 1....... 6034917156us : sys_exit: NR 64 = 31
cyclicte-2321 1....1.. 6034917157us : sys_write -> 0x1f
cyclicte-2321 1....... 6034917159us : sys_enter: NR 64 (4, 408650, 1,
7fbd20bf08, 2, 7fbd20be00)
cyclicte-2321 1....1.. 6034917160us : sys_write(fd: 4, buf: 408650,
count: 1)
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: High latency when running cyclictest
2020-05-07 8:56 High latency when running cyclictest chen song
@ 2020-05-12 10:56 ` chen song
2020-05-12 13:14 ` Steven Rostedt
0 siblings, 1 reply; 4+ messages in thread
From: chen song @ 2020-05-12 10:56 UTC (permalink / raw)
To: linux-rt-users, rostedt
Dear Rostedt,
This is chensong who was asking question in #linux-rt channel. I
upgrated my rt-tests to the lastest version (cyclictest V 1.80) and
trace-cmd as well(trace-cmd version 2.9.dev).
I ran commands like these:
trace-cmd start -e irq -e sched -e timer -p function -l '*spin*';
cyclictest -p 90 -m -c 0 -i 100 -h 100 -q -l 1000000 -b 80 --tracemark
trace-cmd extract
trace-cmd report
The log of last cycle before cyclictest reached the threshold and quit
is like that:
<idle>-0 [000] 130.330659: irq_handler_entry: irq=4 name=arch_timer
<idle>-0 [000] 130.330665: function:
_raw_spin_lock_irqsave
<idle>-0 [000] 130.330666: hrtimer_cancel:
hrtimer=0xffffff801234bdc8
<idle>-0 [000] 130.330667: function:
_raw_spin_unlock_irqrestore
<idle>-0 [000] 130.330668: hrtimer_expire_entry:
hrtimer=0xffffff801234bdc8 now=130207149982 function=hrtimer_wakeup/0x0
<idle>-0 [000] 130.330669: function:
_raw_spin_lock_irqsave
<idle>-0 [000] 130.330682: sched_waking: comm=cyclictest
pid=1720 prio=9 target_cpu=000
<idle>-0 [000] 130.330695: function: _raw_spin_lock
<idle>-0 [000] 130.330697: function: _raw_spin_lock
<idle>-0 [000] 130.330699: sched_wakeup: cyclictest:1720
[9] success=1 CPU:000
<idle>-0 [000] 130.330699: function:
_raw_spin_unlock_irqrestore
<idle>-0 [000] 130.330700: hrtimer_expire_exit:
hrtimer=0xffffff801234bdc8
<idle>-0 [000] 130.330701: function: _raw_spin_lock_irq
<idle>-0 [000] 130.330702: function:
_raw_spin_unlock_irqrestore
<idle>-0 [000] 130.330703: irq_handler_exit: irq=4 ret=handled
It took 44us from irq_handler_entry to irq_handler_exit, compare to
normal case which generally took only around 15us, it produced around
30us extra latency. I also found something wrong like
"_raw_spin_lock_irqsave from 130.330669 to 130.330682" and "sched_waking
from 130.330682 to 130.330695".
PS: cyclictest was running on CPU0 and a firefox was running on CPU1
meanwhile.
I tried to dig deeper, is there any way to find more information, please
let me know, many thanks.
Here is more log for reference:
<idle>-0 [000] 130.330659: irq_handler_entry: irq=4 name=arch_timer
<idle>-0 [000] 130.330665: function:
_raw_spin_lock_irqsave
<idle>-0 [000] 130.330666: hrtimer_cancel:
hrtimer=0xffffff801234bdc8
<idle>-0 [000] 130.330667: function:
_raw_spin_unlock_irqrestore
<idle>-0 [000] 130.330668: hrtimer_expire_entry:
hrtimer=0xffffff801234bdc8 now=130207149982 function=hrtimer_wakeup/0x0
<idle>-0 [000] 130.330669: function:
_raw_spin_lock_irqsave
<idle>-0 [000] 130.330682: sched_waking:
comm=cyclictest pid=1720 prio=9 target_cpu=000
<idle>-0 [000] 130.330695: function:
_raw_spin_lock
<idle>-0 [000] 130.330697: function:
_raw_spin_lock
<idle>-0 [000] 130.330699: sched_wakeup:
cyclictest:1720 [9] success=1 CPU:000
<idle>-0 [000] 130.330699: function:
_raw_spin_unlock_irqrestore
<idle>-0 [000] 130.330700: hrtimer_expire_exit:
hrtimer=0xffffff801234bdc8
<idle>-0 [000] 130.330701: function:
_raw_spin_lock_irq
<idle>-0 [000] 130.330702: function:
_raw_spin_unlock_irqrestore
<idle>-0 [000] 130.330703: irq_handler_exit: irq=4
ret=handled
firefox-1722 [001] 130.330705: function:
_raw_spin_lock_irqsave
<idle>-0 [000] 130.330706: function:
_raw_spin_lock_irqsave
<idle>-0 [000] 130.330706: hrtimer_cancel:
hrtimer=0xffffffc07ffbe960
firefox-1722 [001] 130.330706: function:
_raw_spin_lock
firefox-1722 [001] 130.330707: function:
_raw_spin_unlock_irqrestore
<idle>-0 [000] 130.330708: function:
_raw_spin_unlock_irqrestore
firefox-1722 [001] 130.330708: function:
rt_spin_lock
<idle>-0 [000] 130.330709: function:
_raw_spin_lock_irqsave
<idle>-0 [000] 130.330709: hrtimer_start:
hrtimer=0xffffffc07ffbe960 function=tick_sched_timer/0x0
expires=130210000000 softexpires=130210000000
<idle>-0 [000] 130.330711: function:
_raw_spin_unlock_irqrestore
firefox-1722 [001] 130.330711: function:
rt_spin_unlock
firefox-1722 [001] 130.330712: function:
_raw_spin_lock_irqsave
<idle>-0 [000] 130.330712: function:
_raw_spin_lock
firefox-1722 [001] 130.330712: function:
_raw_spin_lock
firefox-1722 [001] 130.330713: function:
_raw_spin_unlock_irqrestore
<idle>-0 [000] 130.330713: sched_switch:
swapper/0:0 [120] R ==> cyclictest:1720 [9]
firefox-1722 [001] 130.330714: function:
_raw_spin_lock_irqsave
cyclictest-1720 [000] 130.330715: function:
_raw_spin_unlock_irq
firefox-1722 [001] 130.330715: function:
_raw_spin_lock
firefox-1722 [001] 130.330716: function:
_raw_spin_unlock_irqrestore
firefox-1722 [001] 130.330718: function:
_raw_spin_lock_irqsave
firefox-1722 [001] 130.330719: function:
_raw_spin_lock
firefox-1722 [001] 130.330719: function:
_raw_spin_unlock_irqrestore
firefox-1722 [001] 130.330722: function:
rt_spin_lock
firefox-1722 [001] 130.330722: function:
_raw_spin_lock_irqsave
firefox-1722 [001] 130.330723: function:
_raw_spin_lock
firefox-1722 [001] 130.330724: function:
_raw_spin_unlock_irqrestore
firefox-1722 [001] 130.330726: function:
rt_spin_lock
firefox-1722 [001] 130.330727: function:
rt_spin_unlock
firefox-1722 [001] 130.330728: function:
rt_spin_lock
firefox-1722 [001] 130.330729: function:
rt_spin_unlock
firefox-1722 [001] 130.330730: function:
rt_spin_unlock
firefox-1722 [001] 130.330731: function:
_raw_spin_lock_irqsave
firefox-1722 [001] 130.330732: function:
_raw_spin_lock
firefox-1722 [001] 130.330733: function:
_raw_spin_unlock_irqrestore
cyclictest-1720 [000] 130.330749: print:
tracing_mark_write: hit latency threshold (84 > 80)
BR
/Song
On Thu, May 7, 2020 at 4:56 PM chen song <lhcs2008@gmail.com> wrote:
>
> Dear experts,
>
> I had a 4.14.4 kernel with its rtpatch running on a dual-core arm64
> device, the desktop is ubuntu.
>
> In general, the max latency of cyclictest is around 50us in empty load
> which is acceptable. However, if i open a firefox duing cyclictest is
> running, the max latency becomes higher up to 200us.
>
> I tried to use ftrace to debug this issue,"cyclictest -p 90 -m -c 0 -i
> 10 -n -h 100 -q -l 10000000 -b 80", "-b 80" means enable ftrace event
> and terminate cyclictest when latency is higher than 80us.
>
> Here is a piece of log:
>
> 6034916919us+: cpu_idle: state=1 cpu_id=1
> 6034916981us+: hrtimer_cancel: hrtimer=ffffff8012663dc8
> 6034916994us+: sched_waking: comm=cyclictest pid=2321 prio=9 target_cpu=001
> 6034917032us+: cpu_idle: state=4294967295 cpu_id=1
> 6034917044us+: hrtimer_start: hrtimer=ffffffc07ffd5960
> function=tick_sched_timer expires=6034920000000
> softexpires=6034920000000 mode=ABS|PINNED
> 6034917066us+: sys_clock_nanosleep -> 0x0
>
> In this case, I can only see it's stalled in some points but i could'n
> find what happens, in other words, the root cause of the latency.
>
> Is there any better way to debug this issue? I guess some of you might
> meet the same issue, how did you approach to the root cause? I would
> appreciate it so much if you could give me some advice, many thanks.
>
> Best regards,
>
> /Song
>
>
> ============================================================
> Here is the log for reference:
> <idle>-0 1d..h1.. 6034916878us : irq_handler_entry: irq=3
> name=arch_timer -- this is a normal routine
> <idle>-0 1d..h2.. 6034916879us : hrtimer_cancel:
> hrtimer=ffffff8012663dc8
> <idle>-0 1d..h1.. 6034916879us : hrtimer_expire_entry:
> hrtimer=ffffff8012663dc8 function=hrtimer_wakeup now=6034916525493
> <idle>-0 1d..h2.. 6034916880us : sched_waking: comm=cyclictest
> pid=2321 prio=9 target_cpu=001
> <idle>-0 1dn.h3.. 6034916882us : sched_wakeup: comm=cyclictest
> pid=2321 prio=9 target_cpu=001
> <idle>-0 1dn.h1.. 6034916883us : hrtimer_expire_exit:
> hrtimer=ffffff8012663dc8
> <idle>-0 1dn.h1.. 6034916884us : irq_handler_exit: irq=3
> ret=handled
> <idle>-0 1.n..1.. 6034916886us : cpu_idle: state=4294967295
> cpu_id=1
> <idle>-0 1dn..2.. 6034916888us : hrtimer_cancel:
> hrtimer=ffffffc07ffd5960
> <idle>-0 1dn..2.. 6034916890us : hrtimer_start:
> hrtimer=ffffffc07ffd5960 function=tick_sched_timer expires=6034920000000
> softexpires=6034920000000 mode=ABS|PINNED
> <idle>-0 1dn..1.. 6034916891us : rcu_utilization: Start context
> switch
> <idle>-0 1dn..1.. 6034916892us : rcu_utilization: End context
> switch
> <idle>-0 1d...2.. 6034916894us : sched_switch:
> prev_comm=swapper/1 prev_pid=0 prev_prio=120 prev_state=R ==>
> next_comm=cyclictest next_pid=2321 next_prio=9
> cyclicte-2321 1....... 6034916897us : kfree:
> call_site=ffffff80081501f0 ptr= (null)
> cyclicte-2321 1....... 6034916898us : sys_exit: NR 115 = 0
> cyclicte-2321 1....1.. 6034916898us : sys_clock_nanosleep -> 0x0
> cyclicte-2321 1....... 6034916902us : sys_enter: NR 115 (1, 1,
> 7fbd20b448, 0, 0, 7fbd20be00)
> cyclicte-2321 1....1.. 6034916903us :
> sys_clock_nanosleep(which_clock: 1, flags: 1, rqtp: 7fbd20b448, rmtp: 0)
> cyclicte-2321 1....... 6034916904us : hrtimer_init:
> hrtimer=ffffff8012663dc8 clockid=CLOCK_MONOTONIC mode=ABS
> cyclicte-2321 1d...1.. 6034916906us : hrtimer_start:
> hrtimer=ffffff8012663dc8 function=hrtimer_wakeup expires=6034916622448
> softexpires=6034916622448 mode=ABS
> cyclicte-2321 1d...1.. 6034916907us : rcu_utilization: Start context
> switch
> cyclicte-2321 1d...1.. 6034916908us : rcu_utilization: End context switch
> cyclicte-2321 1d...2.. 6034916911us : sched_switch:
> prev_comm=cyclictest prev_pid=2321 prev_prio=9 prev_state=S ==>
> next_comm=swapper/1 next_pid=0 next_prio=120
> <idle>-0 1d...1.. 6034916915us : tick_stop: success=1
> dependency=NONE
> <idle>-0 1d...2.. 6034916916us : hrtimer_cancel:
> hrtimer=ffffffc07ffd5960
> <idle>-0 1d...2.. 6034916917us : hrtimer_start:
> hrtimer=ffffffc07ffd5960 function=tick_sched_timer expires=6035010000000
> softexpires=6035010000000 mode=ABS|PINNED
> <idle>-0 1d...1.. 6034916919us+: cpu_idle: state=1 cpu_id=1
> --(1)
> <idle>-0 1d..h1.. 6034916977us : irq_handler_entry: irq=3
> name=arch_timer
> <idle>-0 1d..h2.. 6034916981us+: hrtimer_cancel:
> hrtimer=ffffff8012663dc8 --(2)
> <idle>-0 1d..h1.. 6034916993us : hrtimer_expire_entry:
> hrtimer=ffffff8012663dc8 function=hrtimer_wakeup now=6034916628193
> <idle>-0 1d..h2.. 6034916994us+: sched_waking: comm=cyclictest
> pid=2321 prio=9 target_cpu=001 --(3)
> <idle>-0 1dn.h3.. 6034917016us : sched_wakeup: comm=cyclictest
> pid=2321 prio=9 target_cpu=001
> <idle>-0 1dn.h1.. 6034917016us : hrtimer_expire_exit:
> hrtimer=ffffff8012663dc8
> <idle>-0 1dn.h1.. 6034917026us : irq_handler_exit: irq=3
> ret=handled
> <idle>-0 1.n..1.. 6034917032us+: cpu_idle: state=4294967295
> cpu_id=1 --(4)
> <idle>-0 1dn..2.. 6034917043us : hrtimer_cancel:
> hrtimer=ffffffc07ffd5960
> <idle>-0 1dn..2.. 6034917044us+: hrtimer_start:
> hrtimer=ffffffc07ffd5960 function=tick_sched_timer expires=6034920000000
> softexpires=6034920000000 mode=ABS|PINNED --(5)
> <idle>-0 1dn..1.. 6034917056us : rcu_utilization: Start context
> switch
> <idle>-0 1dn..1.. 6034917057us : rcu_utilization: End context
> switch
> <idle>-0 1d...2.. 6034917062us : sched_switch:
> prev_comm=swapper/1 prev_pid=0 prev_prio=120 prev_state=R ==>
> next_comm=cyclictest next_pid=2321 next_prio=9
> cyclicte-2321 1....... 6034917065us : kfree:
> call_site=ffffff80081501f0 ptr= (null)
> cyclicte-2321 1....... 6034917066us : sys_exit: NR 115 = 0
> cyclicte-2321 1....1.. 6034917066us+: sys_clock_nanosleep -> 0x0
> --(5)
> cyclicte-2321 1....... 6034917142us : sys_enter: NR 64 (5,
> 7fbd20c500, 1f, 7fbd20bf08, 2, 7fbd20be00)
> cyclicte-2321 1....1.. 6034917143us : sys_write(fd: 5, buf:
> 7fbd20c500, count: 1f)
> cyclicte-2321 1....... 6034917151us : tracing_mark_write: hit latency
> threshold (91 > 80)
> cyclicte-2321 1....... 6034917155us : kfree:
> call_site=ffffff80081501f0 ptr= (null)
> cyclicte-2321 1....... 6034917156us : sys_exit: NR 64 = 31
> cyclicte-2321 1....1.. 6034917157us : sys_write -> 0x1f
> cyclicte-2321 1....... 6034917159us : sys_enter: NR 64 (4, 408650, 1,
> 7fbd20bf08, 2, 7fbd20be00)
> cyclicte-2321 1....1.. 6034917160us : sys_write(fd: 4, buf: 408650,
> count: 1)
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: High latency when running cyclictest
2020-05-12 10:56 ` chen song
@ 2020-05-12 13:14 ` Steven Rostedt
[not found] ` <CANAMpFSy14e0WCd5Kz_FQkJv-XGYYx8Zp3WRv1TrUNSMBd=NSQ@mail.gmail.com>
0 siblings, 1 reply; 4+ messages in thread
From: Steven Rostedt @ 2020-05-12 13:14 UTC (permalink / raw)
To: chen song; +Cc: linux-rt-users
On Tue, 12 May 2020 18:56:10 +0800
chen song <lhcs2008@gmail.com> wrote:
> Dear Rostedt,
>
> This is chensong who was asking question in #linux-rt channel. I
> upgrated my rt-tests to the lastest version (cyclictest V 1.80) and
> trace-cmd as well(trace-cmd version 2.9.dev).
>
> I ran commands like these:
> trace-cmd start -e irq -e sched -e timer -p function -l '*spin*';
> cyclictest -p 90 -m -c 0 -i 100 -h 100 -q -l 1000000 -b 80 --tracemark
> trace-cmd extract
> trace-cmd report
>
BTW, trace-cmd report -l, will show the preemption numbers.
> The log of last cycle before cyclictest reached the threshold and quit
> is like that:
Your email client line wrapped everything, and it's unreadable.
Can you send my the trace.dat file. Compress it first.
Thanks,
-- Steve
>
>
> <idle>-0 [000] 130.330659: irq_handler_entry: irq=4 name=arch_timer
> <idle>-0 [000] 130.330665: function:
> _raw_spin_lock_irqsave
> <idle>-0 [000] 130.330666: hrtimer_cancel:
> hrtimer=0xffffff801234bdc8
> <idle>-0 [000] 130.330667: function:
> _raw_spin_unlock_irqrestore
> <idle>-0 [000] 130.330668: hrtimer_expire_entry:
> hrtimer=0xffffff801234bdc8 now=130207149982 function=hrtimer_wakeup/0x0
> <idle>-0 [000] 130.330669: function:
> _raw_spin_lock_irqsave
> <idle>-0 [000] 130.330682: sched_waking: comm=cyclictest
> pid=1720 prio=9 target_cpu=000
> <idle>-0 [000] 130.330695: function: _raw_spin_lock
> <idle>-0 [000] 130.330697: function: _raw_spin_lock
> <idle>-0 [000] 130.330699: sched_wakeup: cyclictest:1720
> [9] success=1 CPU:000
> <idle>-0 [000] 130.330699: function:
> _raw_spin_unlock_irqrestore
> <idle>-0 [000] 130.330700: hrtimer_expire_exit:
> hrtimer=0xffffff801234bdc8
> <idle>-0 [000] 130.330701: function: _raw_spin_lock_irq
> <idle>-0 [000] 130.330702: function:
> _raw_spin_unlock_irqrestore
> <idle>-0 [000] 130.330703: irq_handler_exit: irq=4 ret=handled
>
> It took 44us from irq_handler_entry to irq_handler_exit, compare to
> normal case which generally took only around 15us, it produced around
> 30us extra latency. I also found something wrong like
> "_raw_spin_lock_irqsave from 130.330669 to 130.330682" and "sched_waking
> from 130.330682 to 130.330695".
>
> PS: cyclictest was running on CPU0 and a firefox was running on CPU1
> meanwhile.
>
> I tried to dig deeper, is there any way to find more information, please
> let me know, many thanks.
>
> Here is more log for reference:
>
> <idle>-0 [000] 130.330659: irq_handler_entry: irq=4 name=arch_timer
> <idle>-0 [000] 130.330665: function:
> _raw_spin_lock_irqsave
> <idle>-0 [000] 130.330666: hrtimer_cancel:
> hrtimer=0xffffff801234bdc8
> <idle>-0 [000] 130.330667: function:
> _raw_spin_unlock_irqrestore
> <idle>-0 [000] 130.330668: hrtimer_expire_entry:
> hrtimer=0xffffff801234bdc8 now=130207149982 function=hrtimer_wakeup/0x0
> <idle>-0 [000] 130.330669: function:
> _raw_spin_lock_irqsave
> <idle>-0 [000] 130.330682: sched_waking:
> comm=cyclictest pid=1720 prio=9 target_cpu=000
> <idle>-0 [000] 130.330695: function:
> _raw_spin_lock
> <idle>-0 [000] 130.330697: function:
> _raw_spin_lock
> <idle>-0 [000] 130.330699: sched_wakeup:
> cyclictest:1720 [9] success=1 CPU:000
>
>
> <idle>-0 [000] 130.330699: function:
> _raw_spin_unlock_irqrestore
> <idle>-0 [000] 130.330700: hrtimer_expire_exit:
> hrtimer=0xffffff801234bdc8
> <idle>-0 [000] 130.330701: function:
> _raw_spin_lock_irq
> <idle>-0 [000] 130.330702: function:
> _raw_spin_unlock_irqrestore
> <idle>-0 [000] 130.330703: irq_handler_exit: irq=4
> ret=handled
>
> firefox-1722 [001] 130.330705: function:
> _raw_spin_lock_irqsave
> <idle>-0 [000] 130.330706: function:
> _raw_spin_lock_irqsave
> <idle>-0 [000] 130.330706: hrtimer_cancel:
> hrtimer=0xffffffc07ffbe960
> firefox-1722 [001] 130.330706: function:
> _raw_spin_lock
> firefox-1722 [001] 130.330707: function:
> _raw_spin_unlock_irqrestore
> <idle>-0 [000] 130.330708: function:
> _raw_spin_unlock_irqrestore
> firefox-1722 [001] 130.330708: function:
> rt_spin_lock
> <idle>-0 [000] 130.330709: function:
> _raw_spin_lock_irqsave
> <idle>-0 [000] 130.330709: hrtimer_start:
> hrtimer=0xffffffc07ffbe960 function=tick_sched_timer/0x0
> expires=130210000000 softexpires=130210000000
> <idle>-0 [000] 130.330711: function:
> _raw_spin_unlock_irqrestore
> firefox-1722 [001] 130.330711: function:
> rt_spin_unlock
> firefox-1722 [001] 130.330712: function:
> _raw_spin_lock_irqsave
> <idle>-0 [000] 130.330712: function:
> _raw_spin_lock
> firefox-1722 [001] 130.330712: function:
> _raw_spin_lock
> firefox-1722 [001] 130.330713: function:
> _raw_spin_unlock_irqrestore
> <idle>-0 [000] 130.330713: sched_switch:
> swapper/0:0 [120] R ==> cyclictest:1720 [9]
> firefox-1722 [001] 130.330714: function:
> _raw_spin_lock_irqsave
>
> cyclictest-1720 [000] 130.330715: function:
> _raw_spin_unlock_irq
> firefox-1722 [001] 130.330715: function:
> _raw_spin_lock
> firefox-1722 [001] 130.330716: function:
> _raw_spin_unlock_irqrestore
> firefox-1722 [001] 130.330718: function:
> _raw_spin_lock_irqsave
> firefox-1722 [001] 130.330719: function:
> _raw_spin_lock
> firefox-1722 [001] 130.330719: function:
> _raw_spin_unlock_irqrestore
> firefox-1722 [001] 130.330722: function:
> rt_spin_lock
> firefox-1722 [001] 130.330722: function:
> _raw_spin_lock_irqsave
> firefox-1722 [001] 130.330723: function:
> _raw_spin_lock
> firefox-1722 [001] 130.330724: function:
> _raw_spin_unlock_irqrestore
> firefox-1722 [001] 130.330726: function:
> rt_spin_lock
> firefox-1722 [001] 130.330727: function:
> rt_spin_unlock
> firefox-1722 [001] 130.330728: function:
> rt_spin_lock
> firefox-1722 [001] 130.330729: function:
> rt_spin_unlock
> firefox-1722 [001] 130.330730: function:
> rt_spin_unlock
> firefox-1722 [001] 130.330731: function:
> _raw_spin_lock_irqsave
> firefox-1722 [001] 130.330732: function:
> _raw_spin_lock
> firefox-1722 [001] 130.330733: function:
> _raw_spin_unlock_irqrestore
> cyclictest-1720 [000] 130.330749: print:
> tracing_mark_write: hit latency threshold (84 > 80)
>
> BR
>
> /Song
>
> On Thu, May 7, 2020 at 4:56 PM chen song <lhcs2008@gmail.com> wrote:
> >
> > Dear experts,
> >
> > I had a 4.14.4 kernel with its rtpatch running on a dual-core arm64
> > device, the desktop is ubuntu.
> >
> > In general, the max latency of cyclictest is around 50us in empty load
> > which is acceptable. However, if i open a firefox duing cyclictest is
> > running, the max latency becomes higher up to 200us.
> >
> > I tried to use ftrace to debug this issue,"cyclictest -p 90 -m -c 0 -i
> > 10 -n -h 100 -q -l 10000000 -b 80", "-b 80" means enable ftrace event
> > and terminate cyclictest when latency is higher than 80us.
> >
> > Here is a piece of log:
> >
> > 6034916919us+: cpu_idle: state=1 cpu_id=1
> > 6034916981us+: hrtimer_cancel: hrtimer=ffffff8012663dc8
> > 6034916994us+: sched_waking: comm=cyclictest pid=2321 prio=9 target_cpu=001
> > 6034917032us+: cpu_idle: state=4294967295 cpu_id=1
> > 6034917044us+: hrtimer_start: hrtimer=ffffffc07ffd5960
> > function=tick_sched_timer expires=6034920000000
> > softexpires=6034920000000 mode=ABS|PINNED
> > 6034917066us+: sys_clock_nanosleep -> 0x0
> >
> > In this case, I can only see it's stalled in some points but i could'n
> > find what happens, in other words, the root cause of the latency.
> >
> > Is there any better way to debug this issue? I guess some of you might
> > meet the same issue, how did you approach to the root cause? I would
> > appreciate it so much if you could give me some advice, many thanks.
> >
> > Best regards,
> >
> > /Song
> >
> >
> > ============================================================
> > Here is the log for reference:
> > <idle>-0 1d..h1.. 6034916878us : irq_handler_entry: irq=3
> > name=arch_timer -- this is a normal routine
> > <idle>-0 1d..h2.. 6034916879us : hrtimer_cancel:
> > hrtimer=ffffff8012663dc8
> > <idle>-0 1d..h1.. 6034916879us : hrtimer_expire_entry:
> > hrtimer=ffffff8012663dc8 function=hrtimer_wakeup now=6034916525493
> > <idle>-0 1d..h2.. 6034916880us : sched_waking: comm=cyclictest
> > pid=2321 prio=9 target_cpu=001
> > <idle>-0 1dn.h3.. 6034916882us : sched_wakeup: comm=cyclictest
> > pid=2321 prio=9 target_cpu=001
> > <idle>-0 1dn.h1.. 6034916883us : hrtimer_expire_exit:
> > hrtimer=ffffff8012663dc8
> > <idle>-0 1dn.h1.. 6034916884us : irq_handler_exit: irq=3
> > ret=handled
> > <idle>-0 1.n..1.. 6034916886us : cpu_idle: state=4294967295
> > cpu_id=1
> > <idle>-0 1dn..2.. 6034916888us : hrtimer_cancel:
> > hrtimer=ffffffc07ffd5960
> > <idle>-0 1dn..2.. 6034916890us : hrtimer_start:
> > hrtimer=ffffffc07ffd5960 function=tick_sched_timer expires=6034920000000
> > softexpires=6034920000000 mode=ABS|PINNED
> > <idle>-0 1dn..1.. 6034916891us : rcu_utilization: Start context
> > switch
> > <idle>-0 1dn..1.. 6034916892us : rcu_utilization: End context
> > switch
> > <idle>-0 1d...2.. 6034916894us : sched_switch:
> > prev_comm=swapper/1 prev_pid=0 prev_prio=120 prev_state=R ==>
> > next_comm=cyclictest next_pid=2321 next_prio=9
> > cyclicte-2321 1....... 6034916897us : kfree:
> > call_site=ffffff80081501f0 ptr= (null)
> > cyclicte-2321 1....... 6034916898us : sys_exit: NR 115 = 0
> > cyclicte-2321 1....1.. 6034916898us : sys_clock_nanosleep -> 0x0
> > cyclicte-2321 1....... 6034916902us : sys_enter: NR 115 (1, 1,
> > 7fbd20b448, 0, 0, 7fbd20be00)
> > cyclicte-2321 1....1.. 6034916903us :
> > sys_clock_nanosleep(which_clock: 1, flags: 1, rqtp: 7fbd20b448, rmtp: 0)
> > cyclicte-2321 1....... 6034916904us : hrtimer_init:
> > hrtimer=ffffff8012663dc8 clockid=CLOCK_MONOTONIC mode=ABS
> > cyclicte-2321 1d...1.. 6034916906us : hrtimer_start:
> > hrtimer=ffffff8012663dc8 function=hrtimer_wakeup expires=6034916622448
> > softexpires=6034916622448 mode=ABS
> > cyclicte-2321 1d...1.. 6034916907us : rcu_utilization: Start context
> > switch
> > cyclicte-2321 1d...1.. 6034916908us : rcu_utilization: End context switch
> > cyclicte-2321 1d...2.. 6034916911us : sched_switch:
> > prev_comm=cyclictest prev_pid=2321 prev_prio=9 prev_state=S ==>
> > next_comm=swapper/1 next_pid=0 next_prio=120
> > <idle>-0 1d...1.. 6034916915us : tick_stop: success=1
> > dependency=NONE
> > <idle>-0 1d...2.. 6034916916us : hrtimer_cancel:
> > hrtimer=ffffffc07ffd5960
> > <idle>-0 1d...2.. 6034916917us : hrtimer_start:
> > hrtimer=ffffffc07ffd5960 function=tick_sched_timer expires=6035010000000
> > softexpires=6035010000000 mode=ABS|PINNED
> > <idle>-0 1d...1.. 6034916919us+: cpu_idle: state=1 cpu_id=1
> > --(1)
> > <idle>-0 1d..h1.. 6034916977us : irq_handler_entry: irq=3
> > name=arch_timer
> > <idle>-0 1d..h2.. 6034916981us+: hrtimer_cancel:
> > hrtimer=ffffff8012663dc8 --(2)
> > <idle>-0 1d..h1.. 6034916993us : hrtimer_expire_entry:
> > hrtimer=ffffff8012663dc8 function=hrtimer_wakeup now=6034916628193
> > <idle>-0 1d..h2.. 6034916994us+: sched_waking: comm=cyclictest
> > pid=2321 prio=9 target_cpu=001 --(3)
> > <idle>-0 1dn.h3.. 6034917016us : sched_wakeup: comm=cyclictest
> > pid=2321 prio=9 target_cpu=001
> > <idle>-0 1dn.h1.. 6034917016us : hrtimer_expire_exit:
> > hrtimer=ffffff8012663dc8
> > <idle>-0 1dn.h1.. 6034917026us : irq_handler_exit: irq=3
> > ret=handled
> > <idle>-0 1.n..1.. 6034917032us+: cpu_idle: state=4294967295
> > cpu_id=1 --(4)
> > <idle>-0 1dn..2.. 6034917043us : hrtimer_cancel:
> > hrtimer=ffffffc07ffd5960
> > <idle>-0 1dn..2.. 6034917044us+: hrtimer_start:
> > hrtimer=ffffffc07ffd5960 function=tick_sched_timer expires=6034920000000
> > softexpires=6034920000000 mode=ABS|PINNED --(5)
> > <idle>-0 1dn..1.. 6034917056us : rcu_utilization: Start context
> > switch
> > <idle>-0 1dn..1.. 6034917057us : rcu_utilization: End context
> > switch
> > <idle>-0 1d...2.. 6034917062us : sched_switch:
> > prev_comm=swapper/1 prev_pid=0 prev_prio=120 prev_state=R ==>
> > next_comm=cyclictest next_pid=2321 next_prio=9
> > cyclicte-2321 1....... 6034917065us : kfree:
> > call_site=ffffff80081501f0 ptr= (null)
> > cyclicte-2321 1....... 6034917066us : sys_exit: NR 115 = 0
> > cyclicte-2321 1....1.. 6034917066us+: sys_clock_nanosleep -> 0x0
> > --(5)
> > cyclicte-2321 1....... 6034917142us : sys_enter: NR 64 (5,
> > 7fbd20c500, 1f, 7fbd20bf08, 2, 7fbd20be00)
> > cyclicte-2321 1....1.. 6034917143us : sys_write(fd: 5, buf:
> > 7fbd20c500, count: 1f)
> > cyclicte-2321 1....... 6034917151us : tracing_mark_write: hit latency
> > threshold (91 > 80)
> > cyclicte-2321 1....... 6034917155us : kfree:
> > call_site=ffffff80081501f0 ptr= (null)
> > cyclicte-2321 1....... 6034917156us : sys_exit: NR 64 = 31
> > cyclicte-2321 1....1.. 6034917157us : sys_write -> 0x1f
> > cyclicte-2321 1....... 6034917159us : sys_enter: NR 64 (4, 408650, 1,
> > 7fbd20bf08, 2, 7fbd20be00)
> > cyclicte-2321 1....1.. 6034917160us : sys_write(fd: 4, buf: 408650,
> > count: 1)
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: High latency when running cyclictest
[not found] ` <CANAMpFSy14e0WCd5Kz_FQkJv-XGYYx8Zp3WRv1TrUNSMBd=NSQ@mail.gmail.com>
@ 2020-05-18 2:46 ` chen song
0 siblings, 0 replies; 4+ messages in thread
From: chen song @ 2020-05-18 2:46 UTC (permalink / raw)
To: Steven Rostedt; +Cc: linux-rt-users
Mr. Rostedt,
I sent you trace.data last week and i looked into it in kernelshark meanwhile.I
found it took more than 20us in _raw_spin_unlock_irq.
I looked into the code, the call stack is like that:
hrtimer_try_to_cancel -->
unlock_hrtimer_base -->
raw_spin_unlock_irqrestore -->
do_raw_spin_unlock -->
arch_spin_unlock
or
finish_task_switch -->
finish_lock_switch -->
raw_spin_unlock_irq -->
do_raw_spin_unlock -->
arch_spin_unlock
Normally, it's working fine, however it will be reproduced when a app is
being opened like firefox.
Have you ever had the same problem like latency from a spinlock?Could
you please share me some of
your experience in this case? many thanks.
PS:arch_spin_unlock in arch/arm64/include/asm/spinlock.h
#define arch_spin_lock_flags(lock, flags) arch_spin_lock(lock)
static inline void arch_spin_lock(arch_spinlock_t *lock)
{
unsigned int tmp;
arch_spinlock_t lockval, newval;
asm volatile(
/* Atomically increment the next ticket. */
ARM64_LSE_ATOMIC_INSN(
/* LL/SC */
" prfm pstl1strm, %3\n"
"1: ldaxr %w0, %3\n"
" add %w1, %w0, %w5\n"
" stxr %w2, %w1, %3\n"
" cbnz %w2, 1b\n",
/* LSE atomics */
" mov %w2, %w5\n"
" ldadda %w2, %w0, %3\n"
__nops(3)
)
/* Did we get the lock? */
" eor %w1, %w0, %w0, ror #16\n"
" cbz %w1, 3f\n"
/*
* No: spin on the owner. Send a local event to avoid missing an
* unlock before the exclusive load.
*/
" sevl\n"
"2: wfe\n"
" ldaxrh %w2, %4\n"
" eor %w1, %w2, %w0, lsr #16\n"
" cbnz %w1, 2b\n"
/* We got the lock. Critical section starts here. */
"3:"
: "=&r" (lockval), "=&r" (newval), "=&r" (tmp), "+Q" (*lock)
: "Q" (lock->owner), "I" (1 << TICKET_SHIFT)
: "memory");
}
static inline int arch_spin_trylock(arch_spinlock_t *lock)
{
unsigned int tmp;
arch_spinlock_t lockval;
asm volatile(ARM64_LSE_ATOMIC_INSN(
/* LL/SC */
" prfm pstl1strm, %2\n"
"1: ldaxr %w0, %2\n"
" eor %w1, %w0, %w0, ror #16\n"
" cbnz %w1, 2f\n"
" add %w0, %w0, %3\n"
" stxr %w1, %w0, %2\n"
" cbnz %w1, 1b\n"
"2:",
/* LSE atomics */
" ldr %w0, %2\n"
" eor %w1, %w0, %w0, ror #16\n"
" cbnz %w1, 1f\n"
" add %w1, %w0, %3\n"
" casa %w0, %w1, %2\n"
" and %w1, %w1, #0xffff\n"
" eor %w1, %w1, %w0, lsr #16\n"
"1:")
: "=&r" (lockval), "=&r" (tmp), "+Q" (*lock)
: "I" (1 << TICKET_SHIFT)
: "memory");
return !tmp;
}
static inline void arch_spin_unlock(arch_spinlock_t *lock)
{
unsigned long tmp;
asm volatile(ARM64_LSE_ATOMIC_INSN(
/* LL/SC */
" ldrh %w1, %0\n"
" add %w1, %w1, #1\n"
" stlrh %w1, %0",
/* LSE atomics */
" mov %w1, #1\n"
" staddlh %w1, %0\n"
__nops(1))
: "=Q" (lock->owner), "=&r" (tmp)
:
: "memory");
}
BR
chensong
On Wed, May 13, 2020 at 9:27 AM chen song <lhcs2008@gmail.com> wrote:
>
> Mr. Rostedt,
>
> The compressed trace.dat is in the attachment with trace-cmd report
> followed with "-l". Thanks again for helping me with this. Please let
> me know if there is anything i can do for further investigation.
>
> BR
>
> /Song
>
> On Tue, May 12, 2020 at 9:14 PM Steven Rostedt <rostedt@goodmis.org> wrote:
> >
> > On Tue, 12 May 2020 18:56:10 +0800
> > chen song <lhcs2008@gmail.com> wrote:
> >
> > > Dear Rostedt,
> > >
> > > This is chensong who was asking question in #linux-rt channel. I
> > > upgrated my rt-tests to the lastest version (cyclictest V 1.80) and
> > > trace-cmd as well(trace-cmd version 2.9.dev).
> > >
> > > I ran commands like these:
> > > trace-cmd start -e irq -e sched -e timer -p function -l '*spin*';
> > > cyclictest -p 90 -m -c 0 -i 100 -h 100 -q -l 1000000 -b 80 --tracemark
> > > trace-cmd extract
> > > trace-cmd report
> > >
> >
> > BTW, trace-cmd report -l, will show the preemption numbers.
> >
> > > The log of last cycle before cyclictest reached the threshold and quit
> > > is like that:
> >
> > Your email client line wrapped everything, and it's unreadable.
> >
> > Can you send my the trace.dat file. Compress it first.
> >
> > Thanks,
> >
> > -- Steve
> >
> > >
> > >
> > > <idle>-0 [000] 130.330659: irq_handler_entry: irq=4 name=arch_timer
> > > <idle>-0 [000] 130.330665: function:
> > > _raw_spin_lock_irqsave
> > > <idle>-0 [000] 130.330666: hrtimer_cancel:
> > > hrtimer=0xffffff801234bdc8
> > > <idle>-0 [000] 130.330667: function:
> > > _raw_spin_unlock_irqrestore
> > > <idle>-0 [000] 130.330668: hrtimer_expire_entry:
> > > hrtimer=0xffffff801234bdc8 now=130207149982 function=hrtimer_wakeup/0x0
> > > <idle>-0 [000] 130.330669: function:
> > > _raw_spin_lock_irqsave
> > > <idle>-0 [000] 130.330682: sched_waking: comm=cyclictest
> > > pid=1720 prio=9 target_cpu=000
> > > <idle>-0 [000] 130.330695: function: _raw_spin_lock
> > > <idle>-0 [000] 130.330697: function: _raw_spin_lock
> > > <idle>-0 [000] 130.330699: sched_wakeup: cyclictest:1720
> > > [9] success=1 CPU:000
> > > <idle>-0 [000] 130.330699: function:
> > > _raw_spin_unlock_irqrestore
> > > <idle>-0 [000] 130.330700: hrtimer_expire_exit:
> > > hrtimer=0xffffff801234bdc8
> > > <idle>-0 [000] 130.330701: function: _raw_spin_lock_irq
> > > <idle>-0 [000] 130.330702: function:
> > > _raw_spin_unlock_irqrestore
> > > <idle>-0 [000] 130.330703: irq_handler_exit: irq=4 ret=handled
> > >
> > > It took 44us from irq_handler_entry to irq_handler_exit, compare to
> > > normal case which generally took only around 15us, it produced around
> > > 30us extra latency. I also found something wrong like
> > > "_raw_spin_lock_irqsave from 130.330669 to 130.330682" and "sched_waking
> > > from 130.330682 to 130.330695".
> > >
> > > PS: cyclictest was running on CPU0 and a firefox was running on CPU1
> > > meanwhile.
> > >
> > > I tried to dig deeper, is there any way to find more information, please
> > > let me know, many thanks.
> > >
> > > Here is more log for reference:
> > >
> > > <idle>-0 [000] 130.330659: irq_handler_entry: irq=4 name=arch_timer
> > > <idle>-0 [000] 130.330665: function:
> > > _raw_spin_lock_irqsave
> > > <idle>-0 [000] 130.330666: hrtimer_cancel:
> > > hrtimer=0xffffff801234bdc8
> > > <idle>-0 [000] 130.330667: function:
> > > _raw_spin_unlock_irqrestore
> > > <idle>-0 [000] 130.330668: hrtimer_expire_entry:
> > > hrtimer=0xffffff801234bdc8 now=130207149982 function=hrtimer_wakeup/0x0
> > > <idle>-0 [000] 130.330669: function:
> > > _raw_spin_lock_irqsave
> > > <idle>-0 [000] 130.330682: sched_waking:
> > > comm=cyclictest pid=1720 prio=9 target_cpu=000
> > > <idle>-0 [000] 130.330695: function:
> > > _raw_spin_lock
> > > <idle>-0 [000] 130.330697: function:
> > > _raw_spin_lock
> > > <idle>-0 [000] 130.330699: sched_wakeup:
> > > cyclictest:1720 [9] success=1 CPU:000
> > >
> > >
> > > <idle>-0 [000] 130.330699: function:
> > > _raw_spin_unlock_irqrestore
> > > <idle>-0 [000] 130.330700: hrtimer_expire_exit:
> > > hrtimer=0xffffff801234bdc8
> > > <idle>-0 [000] 130.330701: function:
> > > _raw_spin_lock_irq
> > > <idle>-0 [000] 130.330702: function:
> > > _raw_spin_unlock_irqrestore
> > > <idle>-0 [000] 130.330703: irq_handler_exit: irq=4
> > > ret=handled
> > >
> > > firefox-1722 [001] 130.330705: function:
> > > _raw_spin_lock_irqsave
> > > <idle>-0 [000] 130.330706: function:
> > > _raw_spin_lock_irqsave
> > > <idle>-0 [000] 130.330706: hrtimer_cancel:
> > > hrtimer=0xffffffc07ffbe960
> > > firefox-1722 [001] 130.330706: function:
> > > _raw_spin_lock
> > > firefox-1722 [001] 130.330707: function:
> > > _raw_spin_unlock_irqrestore
> > > <idle>-0 [000] 130.330708: function:
> > > _raw_spin_unlock_irqrestore
> > > firefox-1722 [001] 130.330708: function:
> > > rt_spin_lock
> > > <idle>-0 [000] 130.330709: function:
> > > _raw_spin_lock_irqsave
> > > <idle>-0 [000] 130.330709: hrtimer_start:
> > > hrtimer=0xffffffc07ffbe960 function=tick_sched_timer/0x0
> > > expires=130210000000 softexpires=130210000000
> > > <idle>-0 [000] 130.330711: function:
> > > _raw_spin_unlock_irqrestore
> > > firefox-1722 [001] 130.330711: function:
> > > rt_spin_unlock
> > > firefox-1722 [001] 130.330712: function:
> > > _raw_spin_lock_irqsave
> > > <idle>-0 [000] 130.330712: function:
> > > _raw_spin_lock
> > > firefox-1722 [001] 130.330712: function:
> > > _raw_spin_lock
> > > firefox-1722 [001] 130.330713: function:
> > > _raw_spin_unlock_irqrestore
> > > <idle>-0 [000] 130.330713: sched_switch:
> > > swapper/0:0 [120] R ==> cyclictest:1720 [9]
> > > firefox-1722 [001] 130.330714: function:
> > > _raw_spin_lock_irqsave
> > >
> > > cyclictest-1720 [000] 130.330715: function:
> > > _raw_spin_unlock_irq
> > > firefox-1722 [001] 130.330715: function:
> > > _raw_spin_lock
> > > firefox-1722 [001] 130.330716: function:
> > > _raw_spin_unlock_irqrestore
> > > firefox-1722 [001] 130.330718: function:
> > > _raw_spin_lock_irqsave
> > > firefox-1722 [001] 130.330719: function:
> > > _raw_spin_lock
> > > firefox-1722 [001] 130.330719: function:
> > > _raw_spin_unlock_irqrestore
> > > firefox-1722 [001] 130.330722: function:
> > > rt_spin_lock
> > > firefox-1722 [001] 130.330722: function:
> > > _raw_spin_lock_irqsave
> > > firefox-1722 [001] 130.330723: function:
> > > _raw_spin_lock
> > > firefox-1722 [001] 130.330724: function:
> > > _raw_spin_unlock_irqrestore
> > > firefox-1722 [001] 130.330726: function:
> > > rt_spin_lock
> > > firefox-1722 [001] 130.330727: function:
> > > rt_spin_unlock
> > > firefox-1722 [001] 130.330728: function:
> > > rt_spin_lock
> > > firefox-1722 [001] 130.330729: function:
> > > rt_spin_unlock
> > > firefox-1722 [001] 130.330730: function:
> > > rt_spin_unlock
> > > firefox-1722 [001] 130.330731: function:
> > > _raw_spin_lock_irqsave
> > > firefox-1722 [001] 130.330732: function:
> > > _raw_spin_lock
> > > firefox-1722 [001] 130.330733: function:
> > > _raw_spin_unlock_irqrestore
> > > cyclictest-1720 [000] 130.330749: print:
> > > tracing_mark_write: hit latency threshold (84 > 80)
> > >
> > > BR
> > >
> > > /Song
> > >
> > > On Thu, May 7, 2020 at 4:56 PM chen song <lhcs2008@gmail.com> wrote:
> > > >
> > > > Dear experts,
> > > >
> > > > I had a 4.14.4 kernel with its rtpatch running on a dual-core arm64
> > > > device, the desktop is ubuntu.
> > > >
> > > > In general, the max latency of cyclictest is around 50us in empty load
> > > > which is acceptable. However, if i open a firefox duing cyclictest is
> > > > running, the max latency becomes higher up to 200us.
> > > >
> > > > I tried to use ftrace to debug this issue,"cyclictest -p 90 -m -c 0 -i
> > > > 10 -n -h 100 -q -l 10000000 -b 80", "-b 80" means enable ftrace event
> > > > and terminate cyclictest when latency is higher than 80us.
> > > >
> > > > Here is a piece of log:
> > > >
> > > > 6034916919us+: cpu_idle: state=1 cpu_id=1
> > > > 6034916981us+: hrtimer_cancel: hrtimer=ffffff8012663dc8
> > > > 6034916994us+: sched_waking: comm=cyclictest pid=2321 prio=9 target_cpu=001
> > > > 6034917032us+: cpu_idle: state=4294967295 cpu_id=1
> > > > 6034917044us+: hrtimer_start: hrtimer=ffffffc07ffd5960
> > > > function=tick_sched_timer expires=6034920000000
> > > > softexpires=6034920000000 mode=ABS|PINNED
> > > > 6034917066us+: sys_clock_nanosleep -> 0x0
> > > >
> > > > In this case, I can only see it's stalled in some points but i could'n
> > > > find what happens, in other words, the root cause of the latency.
> > > >
> > > > Is there any better way to debug this issue? I guess some of you might
> > > > meet the same issue, how did you approach to the root cause? I would
> > > > appreciate it so much if you could give me some advice, many thanks.
> > > >
> > > > Best regards,
> > > >
> > > > /Song
> > > >
> > > >
> > > > ============================================================
> > > > Here is the log for reference:
> > > > <idle>-0 1d..h1.. 6034916878us : irq_handler_entry: irq=3
> > > > name=arch_timer -- this is a normal routine
> > > > <idle>-0 1d..h2.. 6034916879us : hrtimer_cancel:
> > > > hrtimer=ffffff8012663dc8
> > > > <idle>-0 1d..h1.. 6034916879us : hrtimer_expire_entry:
> > > > hrtimer=ffffff8012663dc8 function=hrtimer_wakeup now=6034916525493
> > > > <idle>-0 1d..h2.. 6034916880us : sched_waking: comm=cyclictest
> > > > pid=2321 prio=9 target_cpu=001
> > > > <idle>-0 1dn.h3.. 6034916882us : sched_wakeup: comm=cyclictest
> > > > pid=2321 prio=9 target_cpu=001
> > > > <idle>-0 1dn.h1.. 6034916883us : hrtimer_expire_exit:
> > > > hrtimer=ffffff8012663dc8
> > > > <idle>-0 1dn.h1.. 6034916884us : irq_handler_exit: irq=3
> > > > ret=handled
> > > > <idle>-0 1.n..1.. 6034916886us : cpu_idle: state=4294967295
> > > > cpu_id=1
> > > > <idle>-0 1dn..2.. 6034916888us : hrtimer_cancel:
> > > > hrtimer=ffffffc07ffd5960
> > > > <idle>-0 1dn..2.. 6034916890us : hrtimer_start:
> > > > hrtimer=ffffffc07ffd5960 function=tick_sched_timer expires=6034920000000
> > > > softexpires=6034920000000 mode=ABS|PINNED
> > > > <idle>-0 1dn..1.. 6034916891us : rcu_utilization: Start context
> > > > switch
> > > > <idle>-0 1dn..1.. 6034916892us : rcu_utilization: End context
> > > > switch
> > > > <idle>-0 1d...2.. 6034916894us : sched_switch:
> > > > prev_comm=swapper/1 prev_pid=0 prev_prio=120 prev_state=R ==>
> > > > next_comm=cyclictest next_pid=2321 next_prio=9
> > > > cyclicte-2321 1....... 6034916897us : kfree:
> > > > call_site=ffffff80081501f0 ptr= (null)
> > > > cyclicte-2321 1....... 6034916898us : sys_exit: NR 115 = 0
> > > > cyclicte-2321 1....1.. 6034916898us : sys_clock_nanosleep -> 0x0
> > > > cyclicte-2321 1....... 6034916902us : sys_enter: NR 115 (1, 1,
> > > > 7fbd20b448, 0, 0, 7fbd20be00)
> > > > cyclicte-2321 1....1.. 6034916903us :
> > > > sys_clock_nanosleep(which_clock: 1, flags: 1, rqtp: 7fbd20b448, rmtp: 0)
> > > > cyclicte-2321 1....... 6034916904us : hrtimer_init:
> > > > hrtimer=ffffff8012663dc8 clockid=CLOCK_MONOTONIC mode=ABS
> > > > cyclicte-2321 1d...1.. 6034916906us : hrtimer_start:
> > > > hrtimer=ffffff8012663dc8 function=hrtimer_wakeup expires=6034916622448
> > > > softexpires=6034916622448 mode=ABS
> > > > cyclicte-2321 1d...1.. 6034916907us : rcu_utilization: Start context
> > > > switch
> > > > cyclicte-2321 1d...1.. 6034916908us : rcu_utilization: End context switch
> > > > cyclicte-2321 1d...2.. 6034916911us : sched_switch:
> > > > prev_comm=cyclictest prev_pid=2321 prev_prio=9 prev_state=S ==>
> > > > next_comm=swapper/1 next_pid=0 next_prio=120
> > > > <idle>-0 1d...1.. 6034916915us : tick_stop: success=1
> > > > dependency=NONE
> > > > <idle>-0 1d...2.. 6034916916us : hrtimer_cancel:
> > > > hrtimer=ffffffc07ffd5960
> > > > <idle>-0 1d...2.. 6034916917us : hrtimer_start:
> > > > hrtimer=ffffffc07ffd5960 function=tick_sched_timer expires=6035010000000
> > > > softexpires=6035010000000 mode=ABS|PINNED
> > > > <idle>-0 1d...1.. 6034916919us+: cpu_idle: state=1 cpu_id=1
> > > > --(1)
> > > > <idle>-0 1d..h1.. 6034916977us : irq_handler_entry: irq=3
> > > > name=arch_timer
> > > > <idle>-0 1d..h2.. 6034916981us+: hrtimer_cancel:
> > > > hrtimer=ffffff8012663dc8 --(2)
> > > > <idle>-0 1d..h1.. 6034916993us : hrtimer_expire_entry:
> > > > hrtimer=ffffff8012663dc8 function=hrtimer_wakeup now=6034916628193
> > > > <idle>-0 1d..h2.. 6034916994us+: sched_waking: comm=cyclictest
> > > > pid=2321 prio=9 target_cpu=001 --(3)
> > > > <idle>-0 1dn.h3.. 6034917016us : sched_wakeup: comm=cyclictest
> > > > pid=2321 prio=9 target_cpu=001
> > > > <idle>-0 1dn.h1.. 6034917016us : hrtimer_expire_exit:
> > > > hrtimer=ffffff8012663dc8
> > > > <idle>-0 1dn.h1.. 6034917026us : irq_handler_exit: irq=3
> > > > ret=handled
> > > > <idle>-0 1.n..1.. 6034917032us+: cpu_idle: state=4294967295
> > > > cpu_id=1 --(4)
> > > > <idle>-0 1dn..2.. 6034917043us : hrtimer_cancel:
> > > > hrtimer=ffffffc07ffd5960
> > > > <idle>-0 1dn..2.. 6034917044us+: hrtimer_start:
> > > > hrtimer=ffffffc07ffd5960 function=tick_sched_timer expires=6034920000000
> > > > softexpires=6034920000000 mode=ABS|PINNED --(5)
> > > > <idle>-0 1dn..1.. 6034917056us : rcu_utilization: Start context
> > > > switch
> > > > <idle>-0 1dn..1.. 6034917057us : rcu_utilization: End context
> > > > switch
> > > > <idle>-0 1d...2.. 6034917062us : sched_switch:
> > > > prev_comm=swapper/1 prev_pid=0 prev_prio=120 prev_state=R ==>
> > > > next_comm=cyclictest next_pid=2321 next_prio=9
> > > > cyclicte-2321 1....... 6034917065us : kfree:
> > > > call_site=ffffff80081501f0 ptr= (null)
> > > > cyclicte-2321 1....... 6034917066us : sys_exit: NR 115 = 0
> > > > cyclicte-2321 1....1.. 6034917066us+: sys_clock_nanosleep -> 0x0
> > > > --(5)
> > > > cyclicte-2321 1....... 6034917142us : sys_enter: NR 64 (5,
> > > > 7fbd20c500, 1f, 7fbd20bf08, 2, 7fbd20be00)
> > > > cyclicte-2321 1....1.. 6034917143us : sys_write(fd: 5, buf:
> > > > 7fbd20c500, count: 1f)
> > > > cyclicte-2321 1....... 6034917151us : tracing_mark_write: hit latency
> > > > threshold (91 > 80)
> > > > cyclicte-2321 1....... 6034917155us : kfree:
> > > > call_site=ffffff80081501f0 ptr= (null)
> > > > cyclicte-2321 1....... 6034917156us : sys_exit: NR 64 = 31
> > > > cyclicte-2321 1....1.. 6034917157us : sys_write -> 0x1f
> > > > cyclicte-2321 1....... 6034917159us : sys_enter: NR 64 (4, 408650, 1,
> > > > 7fbd20bf08, 2, 7fbd20be00)
> > > > cyclicte-2321 1....1.. 6034917160us : sys_write(fd: 4, buf: 408650,
> > > > count: 1)
> >
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2020-05-18 2:46 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-05-07 8:56 High latency when running cyclictest chen song
2020-05-12 10:56 ` chen song
2020-05-12 13:14 ` Steven Rostedt
[not found] ` <CANAMpFSy14e0WCd5Kz_FQkJv-XGYYx8Zp3WRv1TrUNSMBd=NSQ@mail.gmail.com>
2020-05-18 2:46 ` chen song
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