* Cgroup: iops throttle problem
@ 2016-07-18 13:35 张真
2016-07-20 15:30 ` Tejun Heo
0 siblings, 1 reply; 2+ messages in thread
From: 张真 @ 2016-07-18 13:35 UTC (permalink / raw)
To: tj, aaronlee0817, axboe, mlin, shli, linux-kernel, cgroup,
linux-block, zhen1.zhang, yanzi.zhang, jiale0817.li
Hello
My name is Zhen Zhang , me and Jiale Li recently test and analyze the cgroup
blkio functions.
We tested the buffered read a file using bio when the
blkio.throttle.read_iops_device is set 1000.
The fio result file displays the iops is 13720 larger than 1000 when blocksize
is 4K in fio.
We set different blocksize in fio:
4K, 8K , 16K, 32K, 64K, 128K, 256K, 512K, 1024K
The iops in fio:
13035, 7258, 3711, 1698, 907, 460, 228, 102, 54
When bs is less than 64K, the iops is larger than 1000, when bs is larger than
64K, the iops is less than 1000.
We tested it on ubuntu 16.04 with kernel 4.4.0
Dose this a problem of blkio iops throttle?
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: Cgroup: iops throttle problem
2016-07-18 13:35 Cgroup: iops throttle problem 张真
@ 2016-07-20 15:30 ` Tejun Heo
0 siblings, 0 replies; 2+ messages in thread
From: Tejun Heo @ 2016-07-20 15:30 UTC (permalink / raw)
To: 张真
Cc: aaronlee0817, axboe, mlin, shli, linux-kernel, cgroup,
linux-block, zhen1.zhang, yanzi.zhang, jiale0817.li
Hello,
On Mon, Jul 18, 2016 at 09:35:12PM +0800, 张真 wrote:
> Hello
> My name is Zhen Zhang , me and Jiale Li recently test and analyze the cgroup
> blkio functions.
> We tested the buffered read a file using bio when the
> blkio.throttle.read_iops_device is set 1000.
> The fio result file displays the iops is 13720 larger than 1000 when blocksize
> is 4K in fio.
blk-throttle does allow bursts so the iops might go over the set limit
for a short period. Over time, it shouldn't be over the set limit.
> We set different blocksize in fio:
> 4K, 8K , 16K, 32K, 64K, 128K, 256K, 512K, 1024K
>
> The iops in fio:
> 13035, 7258, 3711, 1698, 907, 460, 228, 102, 54
Looks like you were hitting the natural bandwidth limit of the device.
> When bs is less than 64K, the iops is larger than 1000, when bs is larger than
> 64K, the iops is less than 1000.
> We tested it on ubuntu 16.04 with kernel 4.4.0
>
> Dose this a problem of blkio iops throttle?
I don't know how the test was run but consistently going over the set
limit isn't the expected behavior.
Thanks.
--
tejun
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