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:	Mon, 17 Nov 2008 12:39:10 -0500 (EST)
From:	Mikulas Patocka <mpatocka@...hat.com>
To:	Peter Zijlstra <peterz@...radead.org>
cc:	Alan Cox <alan@...rguk.ukuu.org.uk>, linux-kernel@...r.kernel.org,
	mingo@...e.hu, rml@...h9.net, Alasdair G Kergon <agk@...hat.com>,
	Milan Broz <mbroz@...hat.com>
Subject: Re: Active waiting with yield()

On Sat, 15 Nov 2008, Peter Zijlstra wrote:

> On Fri, 2008-11-14 at 16:41 -0500, Mikulas Patocka wrote:
> 
> > So, use msleep(1) instead of yield() ?
> 
> wait_event() of course!

Why? Why developes don't like active waiting when terminating a driver?
Is there any real workload when 1ms delay on driver unload would be 
problematic? Or don't they like it because of coding style?

L1 cache miss --- 10ns --- on every request, when using wait queues
msleep latency --- 1ms --- on driver termination, when using msleep
--- so if the driver processes more than 100000 requests between reboots, 
wait queues actually slow things down.

Mikulas
--
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/

Powered by blists - more mailing lists

Powered by Openwall GNU/*/Linux Powered by OpenVZ