Why does disk I/O slow down a CPU bound task?

[Dave Johansen]

On Wed, Apr 1, 2015 at 10:39 AM, Reindl Harald <h.reindl at thelounge.net>
wrote:

>
>
> Am 01.04.2015 um 19:36 schrieb Dave Johansen:
>
>> On Wed, Apr 1, 2015 at 1:32 AM, Reindl Harald wrote:
>>
>>     Am 01.04.2015 um 06:53 schrieb Dave Johansen:
>>
>>         I added the call to mlockall() (it did have to be run as root)
>>         on a F21
>>         machine with no swap and the slow down was still visible in the
>> "CPU
>>         bound task"
>>
>>     surely, as expected
>>
>>     http://serverfault.com/questions/12679/can-anyone-
>> explain-precisely-what-iowait-is
>>
>> I don't get how that is expected. The "CPU bound task" is now basically
>> guaranteed to not be doing anything that requires disk access, so the
>> iowait should be 0 for the "CPU bound task"
>>
>
> the purpose of mlockall() was not to solve the problem, it's intention is
> only to reduce side-effects in the test scenario
>

Ok, that makes sense. I was just confused about the link to iowait and
assumed you were implying that it was expected that the "CPU bound task" be
impacted by iowait.
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