linux-kernel - Re: [PATCH] Give kjournald a IOPRIO_CLASS

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]

Date:	Thu, 2 Oct 2008 15:27:47 +0200
From:	Jens Axboe <jens.axboe@...cle.com>
To:	Arjan van de Ven <arjan@...radead.org>
Cc:	Dave Chinner <david@...morbit.com>,
	Andi Kleen <andi@...stfloor.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org, Alan Cox <alan@...rguk.ukuu.org.uk>
Subject: Re: [PATCH] Give kjournald a IOPRIO_CLASS_RT io priority

On Thu, Oct 02 2008, Arjan van de Ven wrote:
> On Thu, 2 Oct 2008 11:45:37 +0200
> Jens Axboe <jens.axboe@...cle.com> wrote:
> 
> > 
> > That's a good idea, just bump the priority a little bit. Arjan, did
> > you test that out? I'd suggest just trying prio level 0 and still
> > using best-effort scheduling. Probably still need the sync marking,
> > would be interesting to experiment with though.
> 
> I looked at 0 but it appears the 0 is the default for everyone...
> if everyone just defaulted to > 0 then yes I would have picked 0.

That's not correct, class BE and value 4 is the default (and the code
defaults to that, if you haven't set a value yourself):

#define IOPRIO_NORM     (4)
static inline int task_ioprio(struct io_context *ioc)
{
        if (ioprio_valid(ioc->ioprio))
                return IOPRIO_PRIO_DATA(ioc->ioprio);

        return IOPRIO_NORM;
}

static inline int task_ioprio_class(struct io_context *ioc)
{
        if (ioprio_valid(ioc->ioprio))
                return IOPRIO_PRIO_CLASS(ioc->ioprio);

        return IOPRIO_CLASS_BE;
}

So if you use IOPRIO_CLASS_BE and 0 for the ioprio, you will have the
highest priority of the default scheduling class.

-- 
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/