diff options
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/dynamic_queue_limits.h | 45 | ||||
| -rw-r--r-- | include/trace/events/napi.h | 33 |
2 files changed, 78 insertions, 0 deletions
diff --git a/include/linux/dynamic_queue_limits.h b/include/linux/dynamic_queue_limits.h index 407c2f281b64..5693a4be0d9a 100644 --- a/include/linux/dynamic_queue_limits.h +++ b/include/linux/dynamic_queue_limits.h @@ -38,14 +38,22 @@ #ifdef __KERNEL__ +#include <linux/bitops.h> #include <asm/bug.h> +#define DQL_HIST_LEN 4 +#define DQL_HIST_ENT(dql, idx) ((dql)->history[(idx) % DQL_HIST_LEN]) + struct dql { /* Fields accessed in enqueue path (dql_queued) */ unsigned int num_queued; /* Total ever queued */ unsigned int adj_limit; /* limit + num_completed */ unsigned int last_obj_cnt; /* Count at last queuing */ + unsigned long history_head; /* top 58 bits of jiffies */ + /* stall entries, a bit per entry */ + unsigned long history[DQL_HIST_LEN]; + /* Fields accessed only by completion path (dql_completed) */ unsigned int limit ____cacheline_aligned_in_smp; /* Current limit */ @@ -62,6 +70,13 @@ struct dql { unsigned int max_limit; /* Max limit */ unsigned int min_limit; /* Minimum limit */ unsigned int slack_hold_time; /* Time to measure slack */ + + /* Stall threshold (in jiffies), defined by user */ + unsigned short stall_thrs; + /* Longest stall detected, reported to user */ + unsigned short stall_max; + unsigned long last_reap; /* Last reap (in jiffies) */ + unsigned long stall_cnt; /* Number of stalls */ }; /* Set some static maximums */ @@ -74,6 +89,8 @@ struct dql { */ static inline void dql_queued(struct dql *dql, unsigned int count) { + unsigned long map, now, now_hi, i; + BUG_ON(count > DQL_MAX_OBJECT); dql->last_obj_cnt = count; @@ -86,6 +103,34 @@ static inline void dql_queued(struct dql *dql, unsigned int count) barrier(); dql->num_queued += count; + + now = jiffies; + now_hi = now / BITS_PER_LONG; + + /* The following code set a bit in the ring buffer, where each + * bit trackes time the packet was queued. The dql->history buffer + * tracks DQL_HIST_LEN * BITS_PER_LONG time (jiffies) slot + */ + if (unlikely(now_hi != dql->history_head)) { + /* About to reuse slots, clear them */ + for (i = 0; i < DQL_HIST_LEN; i++) { + /* Multiplication masks high bits */ + if (now_hi * BITS_PER_LONG == + (dql->history_head + i) * BITS_PER_LONG) + break; + DQL_HIST_ENT(dql, dql->history_head + i + 1) = 0; + } + /* pairs with smp_rmb() in dql_check_stall() */ + smp_wmb(); + WRITE_ONCE(dql->history_head, now_hi); + } + + /* __set_bit() does not guarantee WRITE_ONCE() semantics */ + map = DQL_HIST_ENT(dql, now_hi); + + /* Populate the history with an entry (bit) per queued */ + if (!(map & BIT_MASK(now))) + WRITE_ONCE(DQL_HIST_ENT(dql, now_hi), map | BIT_MASK(now)); } /* Returns how many objects can be queued, < 0 indicates over limit. */ diff --git a/include/trace/events/napi.h b/include/trace/events/napi.h index 6678cf8b235b..dc03cf8e0369 100644 --- a/include/trace/events/napi.h +++ b/include/trace/events/napi.h @@ -36,6 +36,39 @@ TRACE_EVENT(napi_poll, __entry->work, __entry->budget) ); +TRACE_EVENT(dql_stall_detected, + + TP_PROTO(unsigned short thrs, unsigned int len, + unsigned long last_reap, unsigned long hist_head, + unsigned long now, unsigned long *hist), + + TP_ARGS(thrs, len, last_reap, hist_head, now, hist), + + TP_STRUCT__entry( + __field( unsigned short, thrs) + __field( unsigned int, len) + __field( unsigned long, last_reap) + __field( unsigned long, hist_head) + __field( unsigned long, now) + __array( unsigned long, hist, 4) + ), + + TP_fast_assign( + __entry->thrs = thrs; + __entry->len = len; + __entry->last_reap = last_reap; + __entry->hist_head = hist_head * BITS_PER_LONG; + __entry->now = now; + memcpy(__entry->hist, hist, sizeof(entry->hist)); + ), + + TP_printk("thrs %u len %u last_reap %lu hist_head %lu now %lu hist %016lx %016lx %016lx %016lx", + __entry->thrs, __entry->len, + __entry->last_reap, __entry->hist_head, __entry->now, + __entry->hist[0], __entry->hist[1], + __entry->hist[2], __entry->hist[3]) +); + #undef NO_DEV #endif /* _TRACE_NAPI_H */ |