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SubjectRe: [PATCH v4 4/4] rcu: Add RCU stall diagnosis information
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On 2022/11/8 4:38, Elliott, Robert (Servers) wrote:
>
>
>>> Maybe this shouldn't be a table? Make it grep-friendly:
>>> [ 1816.719922] rcu: half-timeout counts: hardirq =5 softirq=10 csw=0
>>> [ 1816.725643] rcu: half_timeout cputimes (ms): time=1500 hardirq=3
>> softirq=0 system=1492
>>
>> I prefer the table. Table look clearer and easier to compare.
>
> Here's an example where it also triggers expedited stalls. The
> self-detected stall prints including the new table can end up
> interleaved with the expedited stall prints.

But even if use your format, it won't solve the printing
interleaving problem. We should use lock.

>
> (the table is expanded a bit here to experiment with adding more info,
> and I included the \t prefixes)
>
> [ 933.728032] tcrypt: rcu testing - kernel_fpu_disable for rude 6 s
> [ 938.038278] rcu: INFO: rcu_preempt detected expedited stalls on CPUs/tasks: { 46-.... } 4 jiffies s: 521 root: 0x8/.
> [ 938.049151] rcu: blocking rcu_node structures (internal RCU debug): l=1:42-55:0x10/.
> [ 938.057236] Sending NMI from CPU 35 to CPUs 46:
> [ 938.062048] NMI backtrace for cpu 46
> [ 938.062050] CPU: 46 PID: 44184 Comm: modprobe Not tainted 6.0.0+ #11
> [ 938.062052] Hardware name: HPE ProLiant DL360 Gen10/ProLiant DL360 Gen10, BIOS U32 03/08/2022
> [ 938.062053] RIP: 0010:rude_sleep_cycles+0x13/0x27 [tcrypt]
> ...
> [ 938.062151] </TASK>
> [ 938.073277] rcu: INFO: rcu_preempt detected expedited stalls on CPUs/tasks: { 46-.... } 289 jiffies s: 521 root: 0x8/.
> [ 938.334292] rcu: blocking rcu_node structures (internal RCU debug): l=1:42-55:0x10/.
> [ 938.342289] Sending NMI from CPU 35 to CPUs 46:
> [ 938.347049] NMI backtrace for cpu 46
> [ 938.347050] CPU: 46 PID: 44184 Comm: modprobe Not tainted 6.0.0+ #11
> [ 938.347051] Hardware name: HPE ProLiant DL360 Gen10/ProLiant DL360 Gen10, BIOS U32 03/08/2022
> [ 938.347052] RIP: 0010:rude_sleep_cycles+0x13/0x27 [tcrypt]
> ...
> [ 938.347121] </TASK>
> [ 938.358275] rcu: INFO: rcu_preempt detected expedited stalls on CPUs/tasks: { 46-.... } 573 jiffies s: 521 root: 0x8/.
> [ 938.619182] rcu: blocking rcu_node structures (internal RCU debug): l=1:42-55:0x10/.
> [ 938.627179] Sending NMI from CPU 35 to CPUs 46:
> [ 938.631939] NMI backtrace for cpu 46
> [ 938.631939] CPU: 46 PID: 44184 Comm: modprobe Not tainted 6.0.0+ #11
> [ 938.631941] Hardware name: HPE ProLiant DL360 Gen10/ProLiant DL360 Gen10, BIOS U32 03/08/2022
> [ 938.631942] RIP: 0010:rude_sleep_cycles+0x13/0x27 [tcrypt]
> ...
> [ 938.631997] </TASK>
> [ 938.643272] rcu: INFO: rcu_preempt detected expedited stalls on CPUs/tasks: {
> [ 938.734267] rcu: INFO: rcu_preempt self-detected stall on CPU
> [ 938.740111] 46-....
> [ 938.747282] rcu: 46-....: (4948 ticks this GP) idle=a9cc/1/0x4000000000000000 softirq=7598/7598 fqs=1253
> [ 938.747285] rcu: hardirqs softirqs csw system cond_resched
> [ 938.747286] rcu: number: 0 0 0 0
> [ 938.754461] } 720 jiffies s: 521 root: 0x8/.
> [ 938.757178] rcu: cputime: 62 0 2436 ==> 2500 (ms)
> [ 938.757179] rcu: current: in_kernel_fpu_begin=1 this_cpu_preemptible=0
> [ 938.757181] (t=5023 jiffies g=61053 q=704 ncpus=56)
> [ 938.759640] rcu: blocking rcu_node structures (internal RCU debug):
>
> The first "46-" line is from the expedited stall.
> The second "46-" line is from the self-detected stall.
> The table lines are from the self-detected stall.
> The "} 720" line is from the expedited stall.
> The "(t=5023" line is from the self-detected stall.
> The "blocking" line is from the expedited stall.
>
> [ 938.761745] CPU: 46 PID: 44184 Comm: modprobe Not tainted 6.0.0+ #11
> [ 938.761747] Hardware name: HPE ProLiant DL360 Gen10/ProLiant DL360 Gen10, BIOS U32 03/08/2022
> [ 938.982118] RIP: 0010:rude_sleep_cycles+0x13/0x27 [tcrypt]
> ...
> [ 939.221833] </TASK>
> [ 939.224239] l=1:42-55:0x10/.
> [ 939.227440] Sending NMI from CPU 35 to CPUs 46:
> [ 939.232204] NMI backtrace for cpu 46
> [ 939.232205] CPU: 46 PID: 44184 Comm: modprobe Not tainted 6.0.0+ #11
> [ 939.232206] Hardware name: HPE ProLiant DL360 Gen10/ProLiant DL360 Gen10, BIOS U32 03/08/2022
> [ 939.232207] RIP: 0010:rude_sleep_cycles+0x13/0x27 [tcrypt]
> ...
> [ 939.232262] </TASK>
> [ 939.243264] rcu: INFO: rcu_preempt detected expedited stalls on CPUs/tasks: { 46-.... } 1458 jiffies s: 521 root: 0x8/.
> [ 939.503926] rcu: blocking rcu_node structures (internal RCU debug): l=1:42-55:0x10/.
> [ 939.511920] Sending NMI from CPU 35 to CPUs 46:
> [ 939.516678] NMI backtrace for cpu 46
> [ 939.516679] CPU: 46 PID: 44184 Comm: modprobe Not tainted 6.0.0+ #11
> [ 939.516680] Hardware name: HPE ProLiant DL360 Gen10/ProLiant DL360 Gen10, BIOS U32 03/08/2022
> [ 939.516680] RIP: 0010:rude_sleep_cycles+0x13/0x27 [tcrypt]
> ...
> [ 939.516732] </TASK>
> [ 939.528263] rcu: INFO: rcu_preempt detected expedited stalls on CPUs/tasks: {
> [ 939.748586] initcall tcrypt_mod_init+0x0/0x1000 [tcrypt] returned -11 after 6020623 usecs
> [ 939.753200] 46-.... } 1718 jiffies s: 521 root: 0x8/.
> [ 939.791580] rcu: blocking rcu_node structures (internal RCU debug):
>
>

--
Regards,
Zhen Lei

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