vrate_adj tracepoint traces vrate changes; however, it does so only when busy_level is non-zero. busy_level turning to zero can sometimes be as interesting an event. This patch also enables vrate_adj tracepoint on other vrate related events - busy_level changes and non-zero nr_lagging.
Signed-off-by: Tejun Heo <[email protected]> --- Hello, Jens. I've encountered vrate regulation issues while testing on a hard disk machine. These are three patches to improve vrate adj visibility and fix the issue. Thanks. block/blk-iocost.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) --- a/block/blk-iocost.c +++ b/block/blk-iocost.c @@ -1343,7 +1343,7 @@ static void ioc_timer_fn(struct timer_li u32 ppm_wthr = MILLION - ioc->params.qos[QOS_WPPM]; u32 missed_ppm[2], rq_wait_pct; u64 period_vtime; - int i; + int prev_busy_level, i; /* how were the latencies during the period? */ ioc_lat_stat(ioc, missed_ppm, &rq_wait_pct); @@ -1531,6 +1531,7 @@ skip_surplus_transfers: * and experiencing shortages but not surpluses, we're too stingy * and should increase vtime rate. */ + prev_busy_level = ioc->busy_level; if (rq_wait_pct > RQ_WAIT_BUSY_PCT || missed_ppm[READ] > ppm_rthr || missed_ppm[WRITE] > ppm_wthr) { @@ -1592,6 +1593,10 @@ skip_surplus_transfers: atomic64_set(&ioc->vtime_rate, vrate); ioc->inuse_margin_vtime = DIV64_U64_ROUND_UP( ioc->period_us * vrate * INUSE_MARGIN_PCT, 100); + } else if (ioc->busy_level != prev_busy_level || nr_lagging) { + trace_iocost_ioc_vrate_adj(ioc, atomic64_read(&ioc->vtime_rate), + &missed_ppm, rq_wait_pct, nr_lagging, + nr_shortages, nr_surpluses); } ioc_refresh_params(ioc, false);
