Re: MQ-BFQ crashing on battery mode

From: Massimo Burcheri
Date: Fri Aug 24 2018 - 02:29:47 EST

On Wed, 2018-08-22 at 11:42 -0600, Jens Axboe wrote:
> Any chance you can try 4.18 at least?

Of course, I tried the sources now, sys-kernel/vanilla-sources-4.18.3
on Gentoo. The issue is the same.

I wonder that nobody has noticed that issue that I can reproduce on many kernels
since 4.13 or even older. Is it a rare combination with my bcache, luks or
btrfs? Or hardware specific? Or scheduler specific, as even BFQ is not that well
tested on btrfs like the default one.

> Schedulers are specific to the queuing infrastructure, so certain types
> will only be available with MQ and certain types will only be available
> on !MQ.

I noticed that. It's just a bit intransparent from the menuconfig, options don't
mention if a scheduler is working on MQ or not, like CONFIG_IOSCHED_BFQ.
There it's written in the description, while CONFIG_MQ_IOSCHED_KYBER has the
note in the name.
Actually MQ schedulers could depend on BLK_MQ to make it obvious.

Best regards,

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