Re: [WIP PATCHSET 0/4] WIP branch for bfq-mq

From: Paolo Valente
Date: Mon Feb 13 2017 - 16:07:22 EST

> Il giorno 10 feb 2017, alle ore 20:49, Paolo Valente <paolo.valente@xxxxxxxxxx> ha scritto:
>> Il giorno 10 feb 2017, alle ore 19:13, Bart Van Assche <bart.vanassche@xxxxxxxxxxx> ha scritto:
>> On 02/10/2017 08:49 AM, Paolo Valente wrote:
>>>> $ grep '^C.*_MQ_' .config
>>> Could you reconfigure with none or mq-deadline as default, check
>>> whether the system boots, and, it it does, switch manually to bfq-mq,
>>> check what happens, and, in the likely case of a failure, try to get
>>> the oops?
>> Hello Paolo,
>> I just finished performing that test with the following kernel config:
>> $ grep '^C.*_MQ_' .config
>> After the system came up I logged in, switched to the bfq-mq scheduler
>> and ran several I/O tests against the boot disk.
> Without any failure, right?
> Unfortunately, as you can imagine, no boot failure occurred on
> any of my test systems so far :(
> This version of bfq-mq can be configured to print all its activity in
> the kernel log, by just defining a macro. This will of course slow
> down the system so much to make it probably unusable, if bfq-mq is
> active from boot. Yet, the failure may still occur so early to make
> this approach useful to discover where bfq-mq gets stuck. As of now I
> have no better ideas. Any suggestion is welcome.

Hi Bart,
I have found a machine crashing at boot, yet not only when bfq-mq is
chosen, but also when mq-deadline is chosen as the default
scheduler. I have found and just reported the cause of the failure,
together with a fix. Probably this is not the cause of your failure,
but what do you think about trying this fix? BTW, I have rebased the
branch [1] against the new commits in Jens for-4.11/next.

Otherwise, if you have no news or suggestions, would you be willing to
try my micro-logging proposal?



> Thanks,
> Paolo
>> Sorry but nothing
>> interesting appeared in the kernel log.
>> Bart.
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