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From: Paolo Valente <paolo.valente@linaro.org>
To: Jeff Moyer <jmoyer@redhat.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>,
	Jens Axboe <axboe@kernel.dk>, Ming Lei <ming.lei@redhat.com>,
	Omar Sandoval <osandov@fb.com>,
	linux-block@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: Setting up default iosched in 5.0+
Date: Fri, 24 May 2019 17:38:41 +0200	[thread overview]
Message-ID: <262EE1CC-7473-4D4C-B108-734ACED1623C@linaro.org> (raw)
In-Reply-To: <x49ftp329lt.fsf@segfault.boston.devel.redhat.com>

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> Il giorno 24 mag 2019, alle ore 16:46, Jeff Moyer <jmoyer@redhat.com> ha scritto:
> 
> Hi, Alexey,
> 
> Alexey Dobriyan <adobriyan@gmail.com> writes:
> 
>> 5.0 deleted three io schedulers and more importantly CONFIG_DEFAULT_IOSCHED
>> option:
>> 
>> 	commit f382fb0bcef4c37dc049e9f6963e3baf204d815c
>> 	block: remove legacy IO schedulers
>> 
>> After figuring out that I silently became "noop" customer enabling just
>> BFQ didn't work: "noop" is still being selected by default.
>> 
>> There is an "elevator=" command line option but it does nothing.
>> 
>> Are users supposed to add stuff to init scripts now?
> 
> A global parameter was never a good idea, because systems often have
> different types of storage installed which benefit from different I/O
> schedulers.  The goal is for the default to just work.
> 

Just for completeness, the current default is the worst possible
choice on all systems with a speed below 500 KIOPS, which includes
practically all personal systems ;) But this is a different story ...

Thanks,
Paolo

> If you feel that the defaults don't work for you, then udev rules are
> the way to go.
> 
> If you also feel that you really do want to set the default for all
> devices, then you can use the following udev rule to emulate the old
> elevator= kernel command line parameter:
> 
> https://github.com/lnykryn/systemd-rhel/blob/rhel-8.0.0/rules/40-elevator.rules
> 
> Cheers,
> Jeff


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  reply	other threads:[~2019-05-24 15:38 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-05-18  9:33 Alexey Dobriyan
2019-05-24 14:46 ` Jeff Moyer
2019-05-24 15:38   ` Paolo Valente [this message]
2019-05-24 18:25   ` Alexey Dobriyan

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