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Date: Mon, 22 Feb 2016 14:01:16 -0800
From: Shaohua Li <shli@...com>
To: <linux-kernel@...r.kernel.org>, <linux-block@...r.kernel.org>
CC: <axboe@...nel.dk>, <tj@...nel.org>,
Vivek Goyal <vgoyal@...hat.com>,
"jmoyer @ redhat . com" <jmoyer@...hat.com>, <Kernel-team@...com>
Subject: [PATCH V2 01/13] block: estimate disk performance
weight based blk-throttling can use the estimated performance to
calculate cgroup bandwidth/IOPS. That said we never can't get accurate
disk performance in a complex workload, a roughly estimation is enough.
One issue is workload might not send enough IO to make disk 100% busy.
The calculation should compensate disk utilization. The calculation
equation is:
bps = (bytes * HZ / time) * (time / busy_time) = bytes * HZ / busy_time
iops = (ios * HZ / time) * (time / busy_time) = ios * HZ / busy_time
Signed-off-by: Shaohua Li <shli@...com>
---
block/blk-core.c | 56 ++++++++++++++++++++++++++++++++++++++++++++++++++
block/blk-sysfs.c | 13 ++++++++++++
include/linux/blkdev.h | 7 +++++++
3 files changed, 76 insertions(+)
diff --git a/block/blk-core.c b/block/blk-core.c
index ab51685..4244f28 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -1919,6 +1919,59 @@ static inline int bio_check_eod(struct bio *bio, unsigned int nr_sectors)
return 0;
}
+#define UPDATE_TIME (HZ / 2)
+static void blk_update_perf(struct request_queue *q,
+ struct hd_struct *p)
+{
+ unsigned long now = jiffies;
+ unsigned long last = q->bw_timestamp;
+ sector_t read_sect, write_sect, tmp_sect;
+ unsigned long read_ios, write_ios, tmp_ios;
+ unsigned long current_ticks;
+ unsigned int busy_ticks;
+
+ if (time_before(now, last + UPDATE_TIME))
+ return;
+
+ if (cmpxchg(&q->bw_timestamp, last, now) != last)
+ return;
+
+ tmp_sect = part_stat_read(p, sectors[READ]);
+ read_sect = tmp_sect - q->last_sects[READ];
+ q->last_sects[READ] = tmp_sect;
+ tmp_sect = part_stat_read(p, sectors[WRITE]);
+ write_sect = tmp_sect - q->last_sects[WRITE];
+ q->last_sects[WRITE] = tmp_sect;
+
+ tmp_ios = part_stat_read(p, ios[READ]);
+ read_ios = tmp_ios - q->last_ios[READ];
+ q->last_ios[READ] = tmp_ios;
+ tmp_ios = part_stat_read(p, ios[WRITE]);
+ write_ios = tmp_ios - q->last_ios[WRITE];
+ q->last_ios[WRITE] = tmp_ios;
+
+ current_ticks = part_stat_read(p, io_ticks);
+ busy_ticks = current_ticks - q->last_ticks;
+ q->last_ticks = current_ticks;
+
+ /* Don't account for long idle */
+ if (now - last > UPDATE_TIME * 2)
+ return;
+ /* Disk load is too low or driver doesn't account io_ticks */
+ if (busy_ticks == 0)
+ return;
+
+ if (busy_ticks > now - last)
+ busy_ticks = now - last;
+
+ tmp_sect = (read_sect + write_sect) * HZ;
+ sector_div(tmp_sect, busy_ticks);
+ q->disk_bw = tmp_sect;
+
+ tmp_ios = (read_ios + write_ios) * HZ / busy_ticks;
+ q->disk_iops = tmp_ios;
+}
+
static noinline_for_stack bool
generic_make_request_checks(struct bio *bio)
{
@@ -1991,6 +2044,9 @@ generic_make_request_checks(struct bio *bio)
*/
create_io_context(GFP_ATOMIC, q->node);
+ blk_update_perf(q,
+ part->partno ? &part_to_disk(part)->part0 : part);
+
if (!blkcg_bio_issue_check(q, bio))
return false;
diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index e140cc4..b59461c 100644
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -348,6 +348,13 @@ static ssize_t queue_poll_store(struct request_queue *q, const char *page,
return ret;
}
+static ssize_t queue_avg_perf_show(struct request_queue *q, char *page)
+{
+ return sprintf(page, "%llu %llu\n",
+ (unsigned long long)q->disk_bw * 512,
+ (unsigned long long)q->disk_iops);
+}
+
static struct queue_sysfs_entry queue_requests_entry = {
.attr = {.name = "nr_requests", .mode = S_IRUGO | S_IWUSR },
.show = queue_requests_show,
@@ -479,6 +486,11 @@ static struct queue_sysfs_entry queue_poll_entry = {
.store = queue_poll_store,
};
+static struct queue_sysfs_entry queue_avg_perf_entry = {
+ .attr = {.name = "average_perf", .mode = S_IRUGO },
+ .show = queue_avg_perf_show,
+};
+
static struct attribute *default_attrs[] = {
&queue_requests_entry.attr,
&queue_ra_entry.attr,
@@ -504,6 +516,7 @@ static struct attribute *default_attrs[] = {
&queue_iostats_entry.attr,
&queue_random_entry.attr,
&queue_poll_entry.attr,
+ &queue_avg_perf_entry.attr,
NULL,
};
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 29189ae..d2d6a7b 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -466,6 +466,13 @@ struct request_queue {
struct bio_set *bio_split;
bool mq_sysfs_init_done;
+
+ unsigned long bw_timestamp;
+ unsigned long last_ticks;
+ sector_t last_sects[2];
+ unsigned long last_ios[2];
+ sector_t disk_bw;
+ unsigned long disk_iops;
};
#define QUEUE_FLAG_QUEUED 1 /* uses generic tag queueing */
--
2.6.5
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