On Tue, 12 May 2020 18:56:10 +0800 chen song <lhcs2008@xxxxxxxxx> 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@xxxxxxxxx> 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)
