rcu: Update RCU's trace.txt documentation for new format
The trace.txt file had obsolete output for the debugfs rcu/rcudata file, so update it. Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>hifive-unleashed-5.1
Paul E. McKenney
Paul E. McKenney
parent
0ea1f2ebeb
commit
2fa218d8bb
|
|
@ -21,23 +21,23 @@ rcu_pending() function decided that there was core RCU work to do).
|
|||
The output of "cat rcu/rcudata" looks as follows:
|
||||
|
||||
rcu_sched:
|
||||
0 c=17829 g=17829 pq=1 pqc=17829 qp=0 dt=10951/1/0 df=1101 of=0 ri=36 ql=0 b=10
|
||||
1 c=17829 g=17829 pq=1 pqc=17829 qp=0 dt=16117/1/0 df=1015 of=0 ri=0 ql=0 b=10
|
||||
2 c=17829 g=17829 pq=1 pqc=17829 qp=0 dt=1445/1/0 df=1839 of=0 ri=0 ql=0 b=10
|
||||
3 c=17829 g=17829 pq=1 pqc=17829 qp=0 dt=6681/1/0 df=1545 of=0 ri=0 ql=0 b=10
|
||||
4 c=17829 g=17829 pq=1 pqc=17829 qp=0 dt=1003/1/0 df=1992 of=0 ri=0 ql=0 b=10
|
||||
5 c=17829 g=17830 pq=1 pqc=17829 qp=1 dt=3887/1/0 df=3331 of=0 ri=4 ql=2 b=10
|
||||
6 c=17829 g=17829 pq=1 pqc=17829 qp=0 dt=859/1/0 df=3224 of=0 ri=0 ql=0 b=10
|
||||
7 c=17829 g=17830 pq=0 pqc=17829 qp=1 dt=3761/1/0 df=1818 of=0 ri=0 ql=2 b=10
|
||||
0!c=423090 g=423091 pq=1 pqc=423090 qp=1 dt=86475/1/0 df=16319 of=163 ri=1519 ql=0 b=10 ci=1460693 co=1648 ca=6448
|
||||
1!c=423329 g=423330 pq=1 pqc=423329 qp=1 dt=90875/1/0 df=16231 of=157 ri=1249 ql=0 b=10 ci=1459002 co=1614 ca=3310
|
||||
2!c=423370 g=423371 pq=1 pqc=423370 qp=1 dt=69661/1/0 df=16125 of=163 ri=1469 ql=0 b=10 ci=1610701 co=2015 ca=2378
|
||||
3!c=422967 g=422968 pq=1 pqc=422967 qp=1 dt=70349/1/0 df=12528 of=163 ri=1450 ql=0 b=10 ci=1427543 co=1430 ca=897
|
||||
4!c=423196 g=423197 pq=1 pqc=423196 qp=0 dt=38935/1/0 df=10959 of=177 ri=1657 ql=0 b=10 ci=1562249 co=1896 ca=533
|
||||
5!c=422950 g=422951 pq=1 pqc=422950 qp=0 dt=25127/1/0 df=5895 of=167 ri=1549 ql=0 b=10 ci=1777260 co=2137 ca=274
|
||||
6!c=423396 g=423397 pq=1 pqc=423396 qp=1 dt=22639/1/0 df=4590 of=149 ri=1572 ql=0 b=10 ci=1471186 co=1530 ca=243
|
||||
7 c=460203 g=460203 pq=1 pqc=460202 qp=0 dt=937087/1/0 df=3298 of=149 ri=1584 ql=6 b=10 ci=4026154 co=1948 ca=135
|
||||
rcu_bh:
|
||||
0 c=-275 g=-275 pq=1 pqc=-275 qp=0 dt=10951/1/0 df=0 of=0 ri=0 ql=0 b=10
|
||||
1 c=-275 g=-275 pq=1 pqc=-275 qp=0 dt=16117/1/0 df=13 of=0 ri=0 ql=0 b=10
|
||||
2 c=-275 g=-275 pq=1 pqc=-275 qp=0 dt=1445/1/0 df=15 of=0 ri=0 ql=0 b=10
|
||||
3 c=-275 g=-275 pq=1 pqc=-275 qp=0 dt=6681/1/0 df=9 of=0 ri=0 ql=0 b=10
|
||||
4 c=-275 g=-275 pq=1 pqc=-275 qp=0 dt=1003/1/0 df=15 of=0 ri=0 ql=0 b=10
|
||||
5 c=-275 g=-275 pq=1 pqc=-275 qp=0 dt=3887/1/0 df=15 of=0 ri=0 ql=0 b=10
|
||||
6 c=-275 g=-275 pq=1 pqc=-275 qp=0 dt=859/1/0 df=15 of=0 ri=0 ql=0 b=10
|
||||
7 c=-275 g=-275 pq=1 pqc=-275 qp=0 dt=3761/1/0 df=15 of=0 ri=0 ql=0 b=10
|
||||
0!c=18446744073709551494 g=18446744073709551494 pq=0 pqc=18446744073709551493 qp=1 dt=86475/1/0 df=11 of=0 ri=0 ql=0 b=10 ci=112 co=0 ca=0
|
||||
1!c=18446744073709551496 g=18446744073709551496 pq=1 pqc=18446744073709551495 qp=0 dt=90875/1/0 df=15 of=0 ri=0 ql=0 b=10 ci=143 co=0 ca=0
|
||||
2!c=18446744073709551496 g=18446744073709551496 pq=1 pqc=18446744073709551495 qp=0 dt=69661/1/0 df=21 of=0 ri=1 ql=0 b=10 ci=88 co=0 ca=0
|
||||
3!c=18446744073709551494 g=18446744073709551494 pq=1 pqc=18446744073709551493 qp=0 dt=70349/1/0 df=13 of=0 ri=0 ql=0 b=10 ci=100 co=0 ca=0
|
||||
4!c=18446744073709551494 g=18446744073709551494 pq=0 pqc=18446744073709551493 qp=1 dt=38935/1/0 df=17 of=0 ri=0 ql=0 b=10 ci=36 co=0 ca=0
|
||||
5!c=18446744073709551494 g=18446744073709551494 pq=0 pqc=18446744073709551493 qp=1 dt=25127/1/0 df=7 of=0 ri=0 ql=0 b=10 ci=32 co=0 ca=0
|
||||
6!c=18446744073709551496 g=18446744073709551496 pq=1 pqc=18446744073709551495 qp=0 dt=22639/1/0 df=9 of=0 ri=0 ql=0 b=10 ci=44 co=0 ca=0
|
||||
7 c=182 g=182 pq=1 pqc=181 qp=0 dt=937087/1/0 df=14 of=0 ri=1 ql=0 b=10 ci=627 co=0 ca=0
|
||||
|
||||
The first section lists the rcu_data structures for rcu_sched, the second
|
||||
for rcu_bh. Note that CONFIG_TREE_PREEMPT_RCU kernels will have an
|
||||
|
|
@ -52,17 +52,18 @@ o The number at the beginning of each line is the CPU number.
|
|||
substantially larger than the number of actual CPUs.
|
||||
|
||||
o "c" is the count of grace periods that this CPU believes have
|
||||
completed. CPUs in dynticks idle mode may lag quite a ways
|
||||
behind, for example, CPU 4 under "rcu_sched" above, which has
|
||||
slept through the past 25 RCU grace periods. It is not unusual
|
||||
to see CPUs lagging by thousands of grace periods.
|
||||
completed. Offlined CPUs and CPUs in dynticks idle mode may
|
||||
lag quite a ways behind, for example, CPU 6 under "rcu_sched"
|
||||
above, which has been offline through not quite 40,000 RCU grace
|
||||
periods. It is not unusual to see CPUs lagging by thousands of
|
||||
grace periods.
|
||||
|
||||
o "g" is the count of grace periods that this CPU believes have
|
||||
started. Again, CPUs in dynticks idle mode may lag behind.
|
||||
If the "c" and "g" values are equal, this CPU has already
|
||||
reported a quiescent state for the last RCU grace period that
|
||||
it is aware of, otherwise, the CPU believes that it owes RCU a
|
||||
quiescent state.
|
||||
started. Again, offlined CPUs and CPUs in dynticks idle mode
|
||||
may lag behind. If the "c" and "g" values are equal, this CPU
|
||||
has already reported a quiescent state for the last RCU grace
|
||||
period that it is aware of, otherwise, the CPU believes that it
|
||||
owes RCU a quiescent state.
|
||||
|
||||
o "pq" indicates that this CPU has passed through a quiescent state
|
||||
for the current grace period. It is possible for "pq" to be
|
||||
|
|
@ -81,14 +82,16 @@ o "pqc" indicates which grace period the last-observed quiescent
|
|||
the next grace period!
|
||||
|
||||
o "qp" indicates that RCU still expects a quiescent state from
|
||||
this CPU.
|
||||
this CPU. Offlined CPUs and CPUs in dyntick idle mode might
|
||||
well have qp=1, which is OK: RCU is still ignoring them.
|
||||
|
||||
o "dt" is the current value of the dyntick counter that is incremented
|
||||
when entering or leaving dynticks idle state, either by the
|
||||
scheduler or by irq. The number after the first "/" is the
|
||||
interrupt nesting depth when in dyntick-idle state, or one
|
||||
greater than the interrupt-nesting depth otherwise. The number
|
||||
after the second "/" is the NMI nesting depth.
|
||||
scheduler or by irq. This number is even if the CPU is in
|
||||
dyntick idle mode and odd otherwise. The number after the first
|
||||
"/" is the interrupt nesting depth when in dyntick-idle state,
|
||||
or one greater than the interrupt-nesting depth otherwise.
|
||||
The number after the second "/" is the NMI nesting depth.
|
||||
|
||||
This field is displayed only for CONFIG_NO_HZ kernels.
|
||||
|
||||
|
|
@ -100,7 +103,7 @@ o "df" is the number of times that some other CPU has forced a
|
|||
|
||||
o "of" is the number of times that some other CPU has forced a
|
||||
quiescent state on behalf of this CPU due to this CPU being
|
||||
offline. In a perfect world, this might neve happen, but it
|
||||
offline. In a perfect world, this might never happen, but it
|
||||
turns out that offlining and onlining a CPU can take several grace
|
||||
periods, and so there is likely to be an extended period of time
|
||||
when RCU believes that the CPU is online when it really is not.
|
||||
|
|
|
|||
Loading…
Reference in New Issue