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Date: Sun, 1 May 2011 06:20:59 -0700 From: "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com> To: linux-kernel@...r.kernel.org Cc: mingo@...e.hu, laijs@...fujitsu.com, dipankar@...ibm.com, akpm@...ux-foundation.org, mathieu.desnoyers@...ymtl.ca, josh@...htriplett.org, niv@...ibm.com, tglx@...utronix.de, peterz@...radead.org, rostedt@...dmis.org, Valdis.Kletnieks@...edu, dhowells@...hat.com, eric.dumazet@...il.com, darren@...art.com, patches@...aro.org, "Paul E. McKenney" <paul.mckenney@...aro.org>, "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com> Subject: [PATCH tip/core/rcu 19/86] rcu: Add forward-progress diagnostic for per-CPU kthreads From: Paul E. McKenney <paul.mckenney@...aro.org> Increment a per-CPU counter on each pass through rcu_cpu_kthread()'s service loop, and add it to the rcudata trace output. Signed-off-by: Paul E. McKenney <paulmck@...ux.vnet.ibm.com> --- Documentation/RCU/trace.txt | 39 ++++++++++++++++++++++----------------- kernel/rcutree.c | 2 ++ kernel/rcutree_trace.c | 4 +++- 3 files changed, 27 insertions(+), 18 deletions(-) diff --git a/Documentation/RCU/trace.txt b/Documentation/RCU/trace.txt index 77f5bda..26d9ee3 100644 --- a/Documentation/RCU/trace.txt +++ b/Documentation/RCU/trace.txt @@ -24,23 +24,23 @@ boosting statistics). The output of "cat rcu/rcudata" looks as follows: rcu_sched: - 0!c=423090 g=423091 pq=1 pqc=423090 qp=1 dt=86475/1/0 df=16319 of=163 ri=1519 ql=0 qs=.... kt=0/W 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 qs=.... kt=0/W 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 qs=.... kt=0/W 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 qs=.... kt=0/W 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 qs=.... kt=0/W 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 qs=.... kt=0/W 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 qs=.... kt=0/W 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 qs=N.W. kt=0/W b=10 ci=4026154 co=1948 ca=135 + 0 c=20972 g=20973 pq=1 pqc=20972 qp=0 dt=545/1/0 df=50 of=0 ri=0 ql=163 qs=NRW. kt=0/W/0 ktl=ebc3 b=10 ci=153737 co=0 ca=0 + 1 c=20972 g=20973 pq=1 pqc=20972 qp=0 dt=967/1/0 df=58 of=0 ri=0 ql=634 qs=NRW. kt=0/W/1 ktl=58c b=10 ci=191037 co=0 ca=0 + 2 c=20972 g=20973 pq=1 pqc=20972 qp=0 dt=1081/1/0 df=175 of=0 ri=0 ql=74 qs=N.W. kt=0/W/2 ktl=da94 b=10 ci=75991 co=0 ca=0 + 3 c=20942 g=20943 pq=1 pqc=20942 qp=1 dt=1846/0/0 df=404 of=0 ri=0 ql=0 qs=.... kt=0/W/3 ktl=d1cd b=10 ci=72261 co=0 ca=0 + 4 c=20972 g=20973 pq=1 pqc=20972 qp=0 dt=369/1/0 df=83 of=0 ri=0 ql=48 qs=N.W. kt=0/W/4 ktl=e0e7 b=10 ci=128365 co=0 ca=0 + 5 c=20972 g=20973 pq=1 pqc=20972 qp=0 dt=381/1/0 df=64 of=0 ri=0 ql=169 qs=NRW. kt=0/W/5 ktl=fb2f b=10 ci=164360 co=0 ca=0 + 6 c=20972 g=20973 pq=1 pqc=20972 qp=0 dt=1037/1/0 df=183 of=0 ri=0 ql=62 qs=N.W. kt=0/W/6 ktl=d2ad b=10 ci=65663 co=0 ca=0 + 7 c=20897 g=20897 pq=1 pqc=20896 qp=0 dt=1572/0/0 df=382 of=0 ri=0 ql=0 qs=.... kt=0/W/7 ktl=cf15 b=10 ci=75006 co=0 ca=0 rcu_bh: - 0!c=18446744073709551494 g=18446744073709551494 pq=0 pqc=18446744073709551493 qp=1 dt=86475/1/0 df=11 of=0 ri=0 ql=0 qs=.... kt=0/W 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 qs=.... kt=0/W 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 qs=.... kt=0/W 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 qs=.... kt=0/W 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 qs=.... kt=0/W 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 qs=.... kt=0/W 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 qs=.... kt=0/W 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 qs=.... kt=0/W b=10 ci=627 co=0 ca=0 + 0 c=1480 g=1480 pq=1 pqc=1479 qp=0 dt=545/1/0 df=6 of=0 ri=1 ql=0 qs=.... kt=0/W/0 ktl=ebc3 b=10 ci=0 co=0 ca=0 + 1 c=1480 g=1480 pq=1 pqc=1479 qp=0 dt=967/1/0 df=3 of=0 ri=1 ql=0 qs=.... kt=0/W/1 ktl=58c b=10 ci=151 co=0 ca=0 + 2 c=1480 g=1480 pq=1 pqc=1479 qp=0 dt=1081/1/0 df=6 of=0 ri=1 ql=0 qs=.... kt=0/W/2 ktl=da94 b=10 ci=0 co=0 ca=0 + 3 c=1480 g=1480 pq=1 pqc=1479 qp=0 dt=1846/0/0 df=8 of=0 ri=1 ql=0 qs=.... kt=0/W/3 ktl=d1cd b=10 ci=0 co=0 ca=0 + 4 c=1480 g=1480 pq=1 pqc=1479 qp=0 dt=369/1/0 df=6 of=0 ri=1 ql=0 qs=.... kt=0/W/4 ktl=e0e7 b=10 ci=0 co=0 ca=0 + 5 c=1480 g=1480 pq=1 pqc=1479 qp=0 dt=381/1/0 df=4 of=0 ri=1 ql=0 qs=.... kt=0/W/5 ktl=fb2f b=10 ci=0 co=0 ca=0 + 6 c=1480 g=1480 pq=1 pqc=1479 qp=0 dt=1037/1/0 df=6 of=0 ri=1 ql=0 qs=.... kt=0/W/6 ktl=d2ad b=10 ci=0 co=0 ca=0 + 7 c=1474 g=1474 pq=1 pqc=1473 qp=0 dt=1572/0/0 df=8 of=0 ri=1 ql=0 qs=.... kt=0/W/7 ktl=cf15 b=10 ci=0 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 @@ -151,7 +151,8 @@ o "qs" gives an indication of the state of the callback queue o "kt" is the per-CPU kernel-thread state. The digit preceding the first slash is zero if there is no work pending and 1 - otherwise. The character between the slashes is as follows: + otherwise. The character between the first pair of slashes is + as follows: "S" The kernel thread is stopped, in other words, all CPUs corresponding to this rcu_node structure are @@ -174,6 +175,10 @@ o "kt" is the per-CPU kernel-thread state. The digit preceding The number after the final slash is the CPU that the kthread is actually running on. +o "ktl" is the low-order 16 bits (in hexadecimal) of the count of + the number of times that this CPU's per-CPU kthread has gone + through its loop servicing invoke_rcu_cpu_kthread() requests. + o "b" is the batch limit for this CPU. If more than this number of RCU callbacks is ready to invoke, then the remainder will be deferred. diff --git a/kernel/rcutree.c b/kernel/rcutree.c index 8cf0307..ee8442d 100644 --- a/kernel/rcutree.c +++ b/kernel/rcutree.c @@ -93,6 +93,7 @@ EXPORT_SYMBOL_GPL(rcu_scheduler_active); static DEFINE_PER_CPU(struct task_struct *, rcu_cpu_kthread_task); DEFINE_PER_CPU(unsigned int, rcu_cpu_kthread_status); DEFINE_PER_CPU(int, rcu_cpu_kthread_cpu); +DEFINE_PER_CPU(unsigned int, rcu_cpu_kthread_loops); static DEFINE_PER_CPU(wait_queue_head_t, rcu_cpu_wq); DEFINE_PER_CPU(char, rcu_cpu_has_work); static char rcu_kthreads_spawnable; @@ -1625,6 +1626,7 @@ static int rcu_cpu_kthread(void *arg) break; } *statusp = RCU_KTHREAD_RUNNING; + per_cpu(rcu_cpu_kthread_loops, cpu)++; local_irq_save(flags); work = *workp; *workp = 0; diff --git a/kernel/rcutree_trace.c b/kernel/rcutree_trace.c index 564b8fe..9678cc3 100644 --- a/kernel/rcutree_trace.c +++ b/kernel/rcutree_trace.c @@ -48,6 +48,7 @@ DECLARE_PER_CPU(unsigned int, rcu_cpu_kthread_status); DECLARE_PER_CPU(unsigned int, rcu_cpu_kthread_cpu); +DECLARE_PER_CPU(unsigned int, rcu_cpu_kthread_loops); DECLARE_PER_CPU(char, rcu_cpu_has_work); static char convert_kthread_status(unsigned int kthread_status) @@ -75,7 +76,7 @@ static void print_one_rcu_data(struct seq_file *m, struct rcu_data *rdp) rdp->dynticks_fqs); #endif /* #ifdef CONFIG_NO_HZ */ seq_printf(m, " of=%lu ri=%lu", rdp->offline_fqs, rdp->resched_ipi); - seq_printf(m, " ql=%ld qs=%c%c%c%c kt=%d/%c/%d b=%ld", + seq_printf(m, " ql=%ld qs=%c%c%c%c kt=%d/%c/%d ktl=%x b=%ld", rdp->qlen, ".N"[rdp->nxttail[RCU_NEXT_READY_TAIL] != rdp->nxttail[RCU_NEXT_TAIL]], @@ -88,6 +89,7 @@ static void print_one_rcu_data(struct seq_file *m, struct rcu_data *rdp) convert_kthread_status(per_cpu(rcu_cpu_kthread_status, rdp->cpu)), per_cpu(rcu_cpu_kthread_cpu, rdp->cpu), + per_cpu(rcu_cpu_kthread_loops, rdp->cpu) & 0xffff, rdp->blimit); seq_printf(m, " ci=%lu co=%lu ca=%lu\n", rdp->n_cbs_invoked, rdp->n_cbs_orphaned, rdp->n_cbs_adopted); -- 1.7.3.2 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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