linux-kernel - Re: [PATCH RFC - TAKE TWO - 00/12] New version of the BFQ I/O Scheduler

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20140602205713.GB8357@kernel.dk>
Date:	Mon, 2 Jun 2014 14:57:30 -0600
From:	Jens Axboe <axboe@...nel.dk>
To:	Tejun Heo <tj@...nel.org>
Cc:	Paolo Valente <paolo.valente@...more.it>,
	Li Zefan <lizefan@...wei.com>,
	Fabio Checconi <fchecconi@...il.com>,
	Arianna Avanzini <avanzini.arianna@...il.com>,
	Paolo Valente <posta_paolo@...oo.it>,
	linux-kernel@...r.kernel.org,
	containers@...ts.linux-foundation.org, cgroups@...r.kernel.org
Subject: Re: [PATCH RFC - TAKE TWO - 00/12] New version of the BFQ I/O
 Scheduler

On Mon, Jun 02 2014, Tejun Heo wrote:
> Hello,
> 
> On Mon, Jun 02, 2014 at 11:46:36AM -0600, Jens Axboe wrote:
> > But blk-mq will potentially drive anything, so it might not be out of
> > the question with a more expensive scheduling variant, if it makes any
> > sense to do of course. At least until there's no more rotating stuff out
> > there :-). But it's not a priority at all to me yet. As long as we have
> > coexisting IO paths, it'd be trivial to select the needed one based on
> > the device characteristics.
> 
> Hmmm... yeah, moving rotating devices over to blk-mq doesn't really
> seem beneficial to me.  I think there are fundamental behavioral
> differences for rotating rusts and newer solid state devices to share
> single code path for things like scheduling and selecting the
> appropriate path depending on the actual devices sounds like a much
> better plan even in the long term.

It's not so much about it being more beneficial to run in blk-mq, as it
is about not having two code paths. But yes, we're likely going to
maintain that code for a long time, so it's not going anywhere anytime
soon.

And for scsi-mq, it's already opt-in, though on a per-host basis. Doing
finer granularity than that is going to be difficult, unless we let
legacy-block and blk-mq share a tag map (though that would not be too
hard).

-- 
Jens Axboe

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/