Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1580983 > unrolled thread

[RFC] blkio_delay_total is calculated mistakenly

Back to article view | Back to linux.kernel

Contents

  [RFC] blkio_delay_total is calculated mistakenly Weiwei Jia <harrynjit@gmail.com> - 2017-02-15 02:30 +0100
    Re: [RFC] blkio_delay_total is calculated mistakenly Greg KH <gregkh@linuxfoundation.org> - 2017-02-15 04:10 +0100
      Re: [RFC] blkio_delay_total is calculated mistakenly Weiwei Jia <harrynjit@gmail.com> - 2017-02-15 04:20 +0100

#1580983 — [RFC] blkio_delay_total is calculated mistakenly

[Multipart message — attachments visible in raw view] — view raw

Hi,

When I read Linux Kernel source codes about how "blkio_delay_total"
(delay waiting for synchronous block I/O to complete for one task) is
calculated in Linux/kernel/delayacct.c file [1], I find that
"blkio_delay_total" adds "task->delays->blkio_delay" to be the total
delay time for one task to wait for synchronous I/O dynamically but
"tsk->delays->blkio_delay" has already been calculated as the total
delay time that one task is waiting for synchronous I/O [2]
dynamically. I think "blkio_delay_total" should not add
"task->delays->blkio_delay" since "task->delays->blkio_delay" is
already the total delay time we want.

Am I missing anything?

BTW, the patch in the attachment may solve this problem if I don't
miss anything. Thank you.


[1] http://lxr.free-electrons.com/source/kernel/delayacct.c?v=4.7#L121
[2] http://lxr.free-electrons.com/source/kernel/delayacct.c?v=4.7#L52

Thanks,
Weiwei Jia

[toc] | [next] | [standalone]

#1581026

On Tue, Feb 14, 2017 at 08:27:36PM -0500, Weiwei Jia wrote:
> Hi,
> 
> When I read Linux Kernel source codes about how "blkio_delay_total"
> (delay waiting for synchronous block I/O to complete for one task) is
> calculated in Linux/kernel/delayacct.c file [1], I find that
> "blkio_delay_total" adds "task->delays->blkio_delay" to be the total
> delay time for one task to wait for synchronous I/O dynamically but
> "tsk->delays->blkio_delay" has already been calculated as the total
> delay time that one task is waiting for synchronous I/O [2]
> dynamically. I think "blkio_delay_total" should not add
> "task->delays->blkio_delay" since "task->delays->blkio_delay" is
> already the total delay time we want.
> 
> Am I missing anything?

Why are you sending this to me?  You have read
Documentation/SubmittingPatches, right?

Please use scripts/get_maintainers.pl for who to send patches to.

thanks,

greg k-h

[toc] | [prev] | [next] | [standalone]

#1581027

On Tue, Feb 14, 2017 at 10:00 PM, Greg KH <gregkh@linuxfoundation.org> wrote:
> On Tue, Feb 14, 2017 at 08:27:36PM -0500, Weiwei Jia wrote:
>> Hi,
>>Balbir Singh <bsingharora@gmail.com>
>> When I read Linux Kernel source codes about how "blkio_delay_total"
>> (delay waiting for synchronous block I/O to complete for one task) is
>> calculated in Linux/kernel/delayacct.c file [1], I find that
>> "blkio_delay_total" adds "task->delays->blkio_delay" to be the total
>> delay time for one task to wait for synchronous I/O dynamically but
>> "tsk->delays->blkio_delay" has already been calculated as the total
>> delay time that one task is waiting for synchronous I/O [2]
>> dynamically. I think "blkio_delay_total" should not add
>> "task->delays->blkio_delay" since "task->delays->blkio_delay" is
>> already the total delay time we want.
>>
>> Am I missing anything?
>
> Why are you sending this to me?  You have read
> Documentation/SubmittingPatches, right?
>
> Please use scripts/get_maintainers.pl for who to send patches to.

Okay. Have cc'ed Balbir Singh <bsingharora@gmail.com> already.

Thanks,
Weiwei Jia

[toc] | [prev] | [standalone]

Back to top | Article view | linux.kernel

csiph-web