Messages in this thread | | | Subject | Re: [PATCH -next 3/3] block: update nsecs[] in part_get_stat() | From | "yukuai (C)" <> | Date | Fri, 1 Apr 2022 11:42:23 +0800 |
| |
在 2022/03/17 19:26, Yu Kuai 写道: > commit 86d7331299fd("block: update io_ticks when io hang") fixed that > %util will be zero for iostat when io is hanged, however, avgqu-sz is > still zero while it represents the number of io that are hunged. On the > other hand, for some slow device, if an io is started before and done > after diskstats is read, the avgqu-sz will be miscalculated. > > To fix the problem, update 'nsecs[]' when part_stat_show() or > diskstats_show() is called. In order to do that, add 'stat_time' in > struct block_device and 'rq_stat_time' in struct request to record the > time. And during iteration, update 'nsecs[]' for each inflight request. Friendly ping... Does anyone have any suggestions on this apporch ?
Thanks, Kuai > > Fixes: 5b18b5a73760 ("block: delete part_round_stats and switch to less precise counting") > Signed-off-by: Yu Kuai <yukuai3@huawei.com> > --- > block/bdev.c | 2 ++ > block/blk-mq.c | 63 ++++++++++++++++++++++++++++++++++++++- > block/blk-mq.h | 2 ++ > block/genhd.c | 25 ++++++++++++++-- > include/linux/blk-mq.h | 2 ++ > include/linux/blk_types.h | 5 ++++ > 6 files changed, 95 insertions(+), 4 deletions(-) > > diff --git a/block/bdev.c b/block/bdev.c > index 13de871fa816..5dced478f190 100644 > --- a/block/bdev.c > +++ b/block/bdev.c > @@ -487,9 +487,11 @@ struct block_device *bdev_alloc(struct gendisk *disk, u8 partno) > bdev = I_BDEV(inode); > mutex_init(&bdev->bd_fsfreeze_mutex); > spin_lock_init(&bdev->bd_size_lock); > + spin_lock_init(&bdev->bd_stat_lock); > bdev->bd_partno = partno; > bdev->bd_inode = inode; > bdev->bd_queue = disk->queue; > + bdev->stat_time = 0; > bdev->bd_stats = alloc_percpu(struct disk_stats); > if (!bdev->bd_stats) { > iput(inode); > diff --git a/block/blk-mq.c b/block/blk-mq.c > index c33fb378b168..7a14d4058b14 100644 > --- a/block/blk-mq.c > +++ b/block/blk-mq.c > @@ -149,6 +149,48 @@ unsigned int blk_mq_in_flight(struct request_queue *q, > return mi.inflight[0] + mi.inflight[1]; > } > > +static bool blk_mq_check_inflight_stat(struct request *rq, void *priv, > + bool reserved) > +{ > + struct mq_inflight *mi = priv; > + > + if ((!mi->part->bd_partno || rq->part == mi->part) && > + blk_mq_rq_state(rq) == MQ_RQ_IN_FLIGHT) { > + u64 stat_time; > + > + mi->inflight[rq_data_dir(rq)]++; > + if (!rq->part) > + return true; > + > + stat_time = READ_ONCE(rq->stat_time_ns); > + /* > + * This might fail if 'req->stat_time_ns' happen to be updated > + * in blk_account_io_done(). > + */ > + if (likely(cmpxchg(&rq->stat_time_ns, stat_time, > + rq->part->stat_time) == stat_time)) { > + int sgrp = op_stat_group(req_op(rq)); > + u64 duation = stat_time ? > + rq->part->stat_time - stat_time : > + rq->part->stat_time - rq->start_time_ns; > + > + part_stat_add(rq->part, nsecs[sgrp], duation); > + } > + } > + > + return true; > +} > + > +unsigned int blk_mq_in_flight_stat(struct request_queue *q, > + struct block_device *part) > +{ > + struct mq_inflight mi = { .part = part }; > + > + blk_mq_queue_tag_busy_iter(q, blk_mq_check_inflight_stat, &mi); > + > + return mi.inflight[0] + mi.inflight[1]; > +} > + > void blk_mq_in_flight_rw(struct request_queue *q, struct block_device *part, > unsigned int inflight[2]) > { > @@ -368,6 +410,7 @@ static struct request *blk_mq_rq_ctx_init(struct blk_mq_alloc_data *data, > rq->start_time_ns = ktime_get_ns(); > else > rq->start_time_ns = 0; > + rq->stat_time_ns = 0; > rq->part = NULL; > #ifdef CONFIG_BLK_RQ_ALLOC_TIME > rq->alloc_time_ns = alloc_time_ns; > @@ -874,7 +917,25 @@ static void __blk_account_io_done(struct request *req, u64 now) > part_stat_lock(); > update_io_ticks(req->part, jiffies, true); > part_stat_inc(req->part, ios[sgrp]); > - part_stat_add(req->part, nsecs[sgrp], now - req->start_time_ns); > + > + if (queue_is_mq(req->q)) { > + u64 stat_time = READ_ONCE(req->stat_time_ns); > + > + /* > + * This might fail if 'req->stat_time_ns' happen to be updated > + * in part_get_stat(). > + */ > + if (likely(cmpxchg(&req->stat_time_ns, stat_time, now) == > + stat_time)) { > + u64 duation = stat_time ? now - stat_time : > + now - req->start_time_ns; > + > + part_stat_add(req->part, nsecs[sgrp], duation); > + } > + } else { > + part_stat_add(req->part, nsecs[sgrp], > + now - req->part->stat_time); > + } > part_stat_unlock(); > } > > diff --git a/block/blk-mq.h b/block/blk-mq.h > index 7d1acf8e1e51..37941f5f1d08 100644 > --- a/block/blk-mq.h > +++ b/block/blk-mq.h > @@ -189,6 +189,8 @@ static inline bool blk_mq_hw_queue_mapped(struct blk_mq_hw_ctx *hctx) > > unsigned int blk_mq_in_flight(struct request_queue *q, > struct block_device *part); > +unsigned int blk_mq_in_flight_stat(struct request_queue *q, > + struct block_device *part); > void blk_mq_in_flight_rw(struct request_queue *q, struct block_device *part, > unsigned int inflight[2]); > > diff --git a/block/genhd.c b/block/genhd.c > index f2c7de2e7ca9..31603c7aff49 100644 > --- a/block/genhd.c > +++ b/block/genhd.c > @@ -953,6 +953,19 @@ ssize_t part_size_show(struct device *dev, > return sprintf(buf, "%llu\n", bdev_nr_sectors(dev_to_bdev(dev))); > } > > +static void part_set_stat_time(struct block_device *part) > +{ > + u64 now = ktime_get_ns(); > + > +again: > + part->stat_time = now; > + > + if (part->bd_partno) { > + part = bdev_whole(part); > + goto again; > + } > +} > + > static unsigned int part_get_stat(struct block_device *bdev, > struct disk_stats *stat) > > @@ -960,10 +973,16 @@ static unsigned int part_get_stat(struct block_device *bdev, > struct request_queue *q = bdev_get_queue(bdev); > unsigned int inflight; > > - if (queue_is_mq(q)) > - inflight = blk_mq_in_flight(q, bdev); > - else > + if (queue_is_mq(q)) { > + spin_lock(&bdev->bd_stat_lock); > + part_stat_lock(); > + part_set_stat_time(bdev); > + inflight = blk_mq_in_flight_stat(q, bdev); > + part_stat_unlock(); > + spin_unlock(&bdev->bd_stat_lock); > + } else { > inflight = part_in_flight(bdev); > + } > > if (inflight) { > part_stat_lock(); > diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h > index e512da636e0f..e98f07d1741c 100644 > --- a/include/linux/blk-mq.h > +++ b/include/linux/blk-mq.h > @@ -108,6 +108,8 @@ struct request { > u64 start_time_ns; > /* Time that I/O was submitted to the device. */ > u64 io_start_time_ns; > + /* Time that I/O was accounted in part_get_stat() */ > + u64 stat_time_ns; > > #ifdef CONFIG_BLK_WBT > unsigned short wbt_flags; > diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h > index c6ed4a559e6a..5cd399b5670d 100644 > --- a/include/linux/blk_types.h > +++ b/include/linux/blk_types.h > @@ -65,6 +65,11 @@ struct block_device { > struct super_block *bd_fsfreeze_sb; > > struct partition_meta_info *bd_meta_info; > + > + /* Prevent part_get_stat() to be called concurrently */ > + spinlock_t bd_stat_lock; > + /* Will be set when part_stat_show() or diskstats_show() is called */ > + u64 stat_time; > #ifdef CONFIG_FAIL_MAKE_REQUEST > bool bd_make_it_fail; > #endif >
| |