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Subject[PATCH] In the current implementation, should_check_rate() returns false if ddir_rw_sum(td->bytes_done)==0. Therefore, a thread may violate the rate if iodepth*bs > rate.
Date
This patch addresses the issue by not checking td->bytes_done in should_check_rate.

An example of the issue:

[root@localhost test]# cat fio_randwrite
[global]
thread
kb_base=1000
direct=1
size=28GiB
group_reporting
io_size=16384
ioengine=libaio
iodepth=2
bs=4096
iodepth_batch_submit=1
iodepth_batch_complete=1
filename=/dev/qblkdev

[fio_randwrite]
rw=randwrite
rate_iops=,1
iodepth_batch_submit=1
thinktime_blocks=1
rate_cycle=1000
thinktime=3s
rate_ignore_thinktime=1

[root@localhost test]# fio fio_randwrite

blktrace output:
259,1 11 1 0.100550729 6135 Q WS 3541608 + 8 [fio]
259,1 11 2 0.100552183 6135 G WS 3541608 + 8 [fio]
259,1 11 3 0.100560373 6135 D WS 3541608 + 8 [fio]
259,1 11 4 0.100570436 6135 C WS 3541608 + 8 [0]
259,1 11 5 0.100599816 6135 Q WS 43470024 + 8 [fio]
259,1 11 6 0.100600513 6135 G WS 43470024 + 8 [fio]
259,1 11 7 0.100601579 6135 D WS 43470024 + 8 [fio]
259,1 11 8 0.100612750 6135 C WS 43470024 + 8 [0]
259,1 11 9 3.101034407 6135 Q WS 49511928 + 8 [fio]
259,1 11 10 3.101036067 6135 G WS 49511928 + 8 [fio]
259,1 11 11 3.101054487 6135 D WS 49511928 + 8 [fio]
259,1 11 12 3.101068699 6135 C WS 49511928 + 8 [0]
259,1 11 13 6.101267480 6135 Q WS 27599368 + 8 [fio]
259,1 11 14 6.101269216 6135 G WS 27599368 + 8 [fio]
259,1 11 15 6.101277050 6135 D WS 27599368 + 8 [fio]
259,1 11 16 6.101287956 6135 C WS 27599368 + 8 [0]

Signed-off-by: HongweiQin <glqinhongwei@gmail.com>
---
fio.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fio.h b/fio.h
index 4d439d9..f5b3990 100644
--- a/fio.h
+++ b/fio.h
@@ -767,7 +767,7 @@ static inline bool should_check_rate(struct thread_data *td)
if (!__should_check_rate(td))
return false;

- return ddir_rw_sum(td->bytes_done) != 0;
+ return true;
}

static inline unsigned long long td_max_bs(struct thread_data *td)
--
1.8.3.1
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