From 3afe7fa535491ecd0382c3968dc2349602bff8a2 Mon Sep 17 00:00:00 2001 From: Joel Fernandes (Google) Date: Sat, 14 Nov 2020 14:31:32 -0500 Subject: rcu/trace: Add tracing for how segcb list changes This commit adds tracing to track how the segcb list changes before/after acceleration, during queuing and during dequeuing. This tracing helped discover an optimization that avoided needless GP requests when no callbacks were accelerated. The tracing overhead is minimal as each segment's length is now stored in the respective segment. Reviewed-by: Frederic Weisbecker Reviewed-by: Neeraj Upadhyay Signed-off-by: Joel Fernandes (Google) Signed-off-by: Paul E. McKenney --- include/trace/events/rcu.h | 26 ++++++++++++++++++++++++++ 1 file changed, 26 insertions(+) (limited to 'include/trace') diff --git a/include/trace/events/rcu.h b/include/trace/events/rcu.h index 155b5cb43cfd..5fc29400e1a2 100644 --- a/include/trace/events/rcu.h +++ b/include/trace/events/rcu.h @@ -505,6 +505,32 @@ TRACE_EVENT_RCU(rcu_callback, __entry->qlen) ); +TRACE_EVENT_RCU(rcu_segcb_stats, + + TP_PROTO(struct rcu_segcblist *rs, const char *ctx), + + TP_ARGS(rs, ctx), + + TP_STRUCT__entry( + __field(const char *, ctx) + __array(unsigned long, gp_seq, RCU_CBLIST_NSEGS) + __array(long, seglen, RCU_CBLIST_NSEGS) + ), + + TP_fast_assign( + __entry->ctx = ctx; + memcpy(__entry->seglen, rs->seglen, RCU_CBLIST_NSEGS * sizeof(long)); + memcpy(__entry->gp_seq, rs->gp_seq, RCU_CBLIST_NSEGS * sizeof(unsigned long)); + + ), + + TP_printk("%s seglen: (DONE=%ld, WAIT=%ld, NEXT_READY=%ld, NEXT=%ld) " + "gp_seq: (DONE=%lu, WAIT=%lu, NEXT_READY=%lu, NEXT=%lu)", __entry->ctx, + __entry->seglen[0], __entry->seglen[1], __entry->seglen[2], __entry->seglen[3], + __entry->gp_seq[0], __entry->gp_seq[1], __entry->gp_seq[2], __entry->gp_seq[3]) + +); + /* * Tracepoint for the registration of a single RCU callback of the special * kvfree() form. The first argument is the RCU type, the second argument -- cgit v1.2.3