diff options
Diffstat (limited to 'block/blk-core.c')
| -rw-r--r-- | block/blk-core.c | 84 |
1 files changed, 84 insertions, 0 deletions
diff --git a/block/blk-core.c b/block/blk-core.c index 93f9152fc271..7d6aeb286271 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -40,6 +40,8 @@ #include "blk-cgroup.h" #include "blk-mq.h" +#include <linux/math64.h> + EXPORT_TRACEPOINT_SYMBOL_GPL(block_bio_remap); EXPORT_TRACEPOINT_SYMBOL_GPL(block_rq_remap); EXPORT_TRACEPOINT_SYMBOL_GPL(block_bio_complete); @@ -3324,3 +3326,85 @@ int __init blk_dev_init(void) return 0; } + +/* + * Blk IO latency support. We want this to be as cheap as possible, so doing + * this lockless (and avoiding atomics), a few off by a few errors in this + * code is not harmful, and we don't want to do anything that is + * perf-impactful. + * TODO : If necessary, we can make the histograms per-cpu and aggregate + * them when printing them out. + */ +void +blk_zero_latency_hist(struct io_latency_state *s) +{ + memset(s->latency_y_axis_read, 0, + sizeof(s->latency_y_axis_read)); + memset(s->latency_y_axis_write, 0, + sizeof(s->latency_y_axis_write)); + s->latency_reads_elems = 0; + s->latency_writes_elems = 0; +} +EXPORT_SYMBOL(blk_zero_latency_hist); + +ssize_t +blk_latency_hist_show(struct io_latency_state *s, char *buf) +{ + int i; + int bytes_written = 0; + u_int64_t num_elem, elem; + int pct; + + num_elem = s->latency_reads_elems; + if (num_elem > 0) { + bytes_written += scnprintf(buf + bytes_written, + PAGE_SIZE - bytes_written, + "IO svc_time Read Latency Histogram (n = %llu):\n", + num_elem); + for (i = 0; + i < ARRAY_SIZE(latency_x_axis_us); + i++) { + elem = s->latency_y_axis_read[i]; + pct = div64_u64(elem * 100, num_elem); + bytes_written += scnprintf(buf + bytes_written, + PAGE_SIZE - bytes_written, + "\t< %5lluus%15llu%15d%%\n", + latency_x_axis_us[i], + elem, pct); + } + /* Last element in y-axis table is overflow */ + elem = s->latency_y_axis_read[i]; + pct = div64_u64(elem * 100, num_elem); + bytes_written += scnprintf(buf + bytes_written, + PAGE_SIZE - bytes_written, + "\t> %5dms%15llu%15d%%\n", 10, + elem, pct); + } + num_elem = s->latency_writes_elems; + if (num_elem > 0) { + bytes_written += scnprintf(buf + bytes_written, + PAGE_SIZE - bytes_written, + "IO svc_time Write Latency Histogram (n = %llu):\n", + num_elem); + for (i = 0; + i < ARRAY_SIZE(latency_x_axis_us); + i++) { + elem = s->latency_y_axis_write[i]; + pct = div64_u64(elem * 100, num_elem); + bytes_written += scnprintf(buf + bytes_written, + PAGE_SIZE - bytes_written, + "\t< %5lluus%15llu%15d%%\n", + latency_x_axis_us[i], + elem, pct); + } + /* Last element in y-axis table is overflow */ + elem = s->latency_y_axis_write[i]; + pct = div64_u64(elem * 100, num_elem); + bytes_written += scnprintf(buf + bytes_written, + PAGE_SIZE - bytes_written, + "\t> %5dms%15llu%15d%%\n", 10, + elem, pct); + } + return bytes_written; +} +EXPORT_SYMBOL(blk_latency_hist_show); |