From: Omar Sandoval <osandov@xxxxxx> When debugging Kyber, it's really useful to know what latencies we've been having and how the domain depths have been adjusted. Add two tracepoints, kyber_latency and kyber_adjust, to record that. Signed-off-by: Omar Sandoval <osandov@xxxxxx> --- block/kyber-iosched.c | 46 +++++++++++++--------- include/trace/events/kyber.h | 76 ++++++++++++++++++++++++++++++++++++ 2 files changed, 104 insertions(+), 18 deletions(-) create mode 100644 include/trace/events/kyber.h diff --git a/block/kyber-iosched.c b/block/kyber-iosched.c index adc8e6393829..d8ddcb4f2435 100644 --- a/block/kyber-iosched.c +++ b/block/kyber-iosched.c @@ -30,6 +30,9 @@ #include "blk-mq-sched.h" #include "blk-mq-tag.h" +#define CREATE_TRACE_POINTS +#include <trace/events/kyber.h> + /* * Scheduling domains: the device is divided into multiple domains based on the * request type. @@ -42,6 +45,13 @@ enum { KYBER_NUM_DOMAINS, }; +static const char *kyber_domain_names[] = { + [KYBER_READ] = "READ", + [KYBER_WRITE] = "WRITE", + [KYBER_DISCARD] = "DISCARD", + [KYBER_OTHER] = "OTHER", +}; + enum { /* * In order to prevent starvation of synchronous requests by a flood of @@ -122,6 +132,11 @@ enum { KYBER_IO_LATENCY, }; +static const char *kyber_latency_type_names[] = { + [KYBER_TOTAL_LATENCY] = "total", + [KYBER_IO_LATENCY] = "I/O", +}; + /* * Per-cpu latency histograms: total latency and I/O latency for each scheduling * domain except for KYBER_OTHER. @@ -144,6 +159,8 @@ struct kyber_ctx_queue { } ____cacheline_aligned_in_smp; struct kyber_queue_data { + struct request_queue *q; + /* * Each scheduling domain has a limited number of in-flight requests * device-wide, limited by these tokens. @@ -249,6 +266,10 @@ static int calculate_percentile(struct kyber_queue_data *kqd, } memset(buckets, 0, sizeof(kqd->latency_buckets[sched_domain][type])); + trace_kyber_latency(kqd->q, kyber_domain_names[sched_domain], + kyber_latency_type_names[type], percentile, + bucket + 1, 1 << KYBER_LATENCY_SHIFT, samples); + return bucket; } @@ -256,8 +277,11 @@ static void kyber_resize_domain(struct kyber_queue_data *kqd, unsigned int sched_domain, unsigned int depth) { depth = clamp(depth, 1U, kyber_depth[sched_domain]); - if (depth != kqd->domain_tokens[sched_domain].sb.depth) + if (depth != kqd->domain_tokens[sched_domain].sb.depth) { sbitmap_queue_resize(&kqd->domain_tokens[sched_domain], depth); + trace_kyber_adjust(kqd->q, kyber_domain_names[sched_domain], + depth); + } } static void kyber_timer_fn(struct timer_list *t) @@ -360,6 +384,8 @@ static struct kyber_queue_data *kyber_queue_data_alloc(struct request_queue *q) if (!kqd) goto err; + kqd->q = q; + kqd->cpu_latency = alloc_percpu_gfp(struct kyber_cpu_latency, GFP_KERNEL | __GFP_ZERO); if (!kqd->cpu_latency) @@ -944,23 +970,7 @@ static int kyber_cur_domain_show(void *data, struct seq_file *m) struct blk_mq_hw_ctx *hctx = data; struct kyber_hctx_data *khd = hctx->sched_data; - switch (khd->cur_domain) { - case KYBER_READ: - seq_puts(m, "READ\n"); - break; - case KYBER_WRITE: - seq_puts(m, "WRITE\n"); - break; - case KYBER_DISCARD: - seq_puts(m, "DISCARD\n"); - break; - case KYBER_OTHER: - seq_puts(m, "OTHER\n"); - break; - default: - seq_printf(m, "%u\n", khd->cur_domain); - break; - } + seq_printf(m, "%s\n", kyber_domain_names[khd->cur_domain]); return 0; } diff --git a/include/trace/events/kyber.h b/include/trace/events/kyber.h new file mode 100644 index 000000000000..9bf85dbef492 --- /dev/null +++ b/include/trace/events/kyber.h @@ -0,0 +1,76 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#undef TRACE_SYSTEM +#define TRACE_SYSTEM kyber + +#if !defined(_TRACE_KYBER_H) || defined(TRACE_HEADER_MULTI_READ) +#define _TRACE_KYBER_H + +#include <linux/blkdev.h> +#include <linux/tracepoint.h> + +#define DOMAIN_LEN 16 +#define LATENCY_TYPE_LEN 8 + +TRACE_EVENT(kyber_latency, + + TP_PROTO(struct request_queue *q, const char *domain, const char *type, + unsigned int percentile, unsigned int numerator, + unsigned int denominator, unsigned int samples), + + TP_ARGS(q, domain, type, percentile, numerator, denominator, samples), + + TP_STRUCT__entry( + __field( dev_t, dev ) + __array( char, domain, DOMAIN_LEN ) + __array( char, type, LATENCY_TYPE_LEN ) + __field( u8, percentile ) + __field( u8, numerator ) + __field( u8, denominator ) + __field( unsigned int, samples ) + ), + + TP_fast_assign( + __entry->dev = disk_devt(dev_to_disk(kobj_to_dev(q->kobj.parent))); + strlcpy(__entry->domain, domain, DOMAIN_LEN); + strlcpy(__entry->type, type, DOMAIN_LEN); + __entry->percentile = percentile; + __entry->numerator = numerator; + __entry->denominator = denominator; + __entry->samples = samples; + ), + + TP_printk("%d,%d %s %s p%u %u/%u samples=%u", + MAJOR(__entry->dev), MINOR(__entry->dev), __entry->domain, + __entry->type, __entry->percentile, __entry->numerator, + __entry->denominator, __entry->samples) +); + +TRACE_EVENT(kyber_adjust, + + TP_PROTO(struct request_queue *q, const char *domain, + unsigned int depth), + + TP_ARGS(q, domain, depth), + + TP_STRUCT__entry( + __field( dev_t, dev ) + __array( char, domain, DOMAIN_LEN ) + __field( unsigned int, depth ) + ), + + TP_fast_assign( + __entry->dev = disk_devt(dev_to_disk(kobj_to_dev(q->kobj.parent))); + strlcpy(__entry->domain, domain, DOMAIN_LEN); + __entry->depth = depth; + ), + + TP_printk("%d,%d %s %u", + MAJOR(__entry->dev), MINOR(__entry->dev), __entry->domain, + __entry->depth) +); + +#define _TRACE_KYBER_H +#endif /* _TRACE_KYBER_H */ + +/* This part must be outside protection */ +#include <trace/define_trace.h> -- 2.18.0