linux-kernel - Re: [PATCH] [RFC] Add support for uevents on block device idle changes

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: <20091118214506.GA17019@srcf.ucam.org>
Date:	Wed, 18 Nov 2009 21:45:06 +0000
From:	Matthew Garrett <mjg59@...f.ucam.org>
To:	Kay Sievers <kay.sievers@...y.org>
Cc:	David Zeuthen <david@...ar.dk>, linux-kernel@...r.kernel.org,
	axboe@...nel.dk, linux-hotplug@...r.kernel.org
Subject: Re: [PATCH] [RFC] Add support for uevents on block device idle
	changes

On Wed, Nov 18, 2009 at 10:39:26PM +0100, Kay Sievers wrote:
> On Wed, Nov 18, 2009 at 22:35, Matthew Garrett <mjg59@...f.ucam.org> wrote:
> > On Wed, Nov 18, 2009 at 10:29:23PM +0100, Kay Sievers wrote:
> >
> >> I guess, the "idle_since" file could be made poll()able, and throw an
> >> event when the idle time is re-set to 0, so the value checking needs
> >> only to happen as long we wait for the disk to become idle. As long as
> >> it's busy anyway, the rare wakeups should not matter much. :)
> >
> > That'd be a userspace wakeup every time something gets submitted to the
> > block device, which sounds far from ideal...
> 
> No, you would only poll() when you reached the timeout and the disk
> entered the idle state. This can not happen more frequently than the
> timeout itself.

I don't understand. idle_since would be reset on every access to the 
block device. The alternative is to generate an event when the disk goes 
idle, but that goes back to requiring a timer in the kernel...

-- 
Matthew Garrett | mjg59@...f.ucam.org
--
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/