From: Pavel Machek <pavel@ucw.cz>
To: Zachary Amsden <zach@vmware.com>
Cc: Alan <alan@lxorguk.ukuu.org.uk>,
Rusty Russell <rusty@rustcorp.com.au>, Andi Kleen <ak@muc.de>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Andrew Morton <akpm@osdl.org>,
Jeremy Fitzhardinge <jeremy@goop.org>,
Chris Wright <chrisw@sous-sol.org>
Subject: Re: [PATCH 9/11] Panic delay fix
Date: Thu, 15 Feb 2007 11:17:13 +0100 [thread overview]
Message-ID: <20070215101713.GK26240@elf.ucw.cz> (raw)
In-Reply-To: <45D36B49.5090109@vmware.com>
Hi!
> >>We'd have to audit and figure out what udelays are for hardware and
> >>which are not, but the evidence is that the vast majority of them are
> >>for hardware and not needed for virtualization.
> >>
> >
> >Which is irrelevant since the hardware drivers won't be used in a
> >virtualised environment with any kind of performance optimisation.
> >
>
> Which is why an audit is irrelevant for the most part. Note on the
> performance below.
You know it is ugly. Alan demonstrated it even hurts performance, but
being ugly is the main problem.
If you _need_ to avoid udelay() in some cases, introduce
udelay_unless_virtualized(), and switch few users to it. Just globaly
defining udelay to nop is _ugly_.
Pavel
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
next prev parent reply other threads:[~2007-02-15 10:17 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-02-06 3:53 Zachary Amsden
2007-02-06 12:27 ` Andi Kleen
2007-02-06 21:59 ` Zachary Amsden
2007-02-07 12:35 ` Pavel Machek
2007-02-07 20:36 ` Rusty Russell
2007-02-07 22:23 ` Zachary Amsden
2007-02-08 14:43 ` Dmitry Torokhov
2007-02-08 21:26 ` Zachary Amsden
2007-02-08 21:37 ` Dmitry Torokhov
2007-02-14 12:26 ` Pavel Machek
2007-02-14 19:47 ` Zachary Amsden
2007-02-14 12:52 ` Alan
2007-02-14 20:04 ` Zachary Amsden
2007-02-14 21:34 ` Alan
2007-02-14 21:53 ` Zachary Amsden
2007-02-15 0:33 ` Alan
2007-02-15 10:17 ` Pavel Machek [this message]
2007-02-15 23:42 ` Zachary Amsden
2007-02-15 23:49 ` Pavel Machek
2007-02-15 23:50 ` Jeremy Fitzhardinge
2007-02-16 3:22 ` Rusty Russell
2007-02-07 14:58 ` Dmitry Torokhov
2007-02-07 22:31 ` Zachary Amsden
2007-02-08 8:24 ` Andi Kleen
2007-02-08 9:08 ` Zachary Amsden
2007-02-08 13:33 ` Andi Kleen
2007-02-08 14:41 ` Dmitry Torokhov
2007-02-14 12:49 ` Alan
2007-02-14 22:51 ` Rusty Russell
2007-02-15 0:28 ` Alan
2007-02-15 13:35 ` Dmitry Torokhov
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