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Re: [Xen-devel] [PATCH] PoD: Check p2m assumption in debug builds

To: Keir Fraser <Keir.Fraser@xxxxxxxxxxxxx>
Subject: Re: [Xen-devel] [PATCH] PoD: Check p2m assumption in debug builds
From: George Dunlap <george.dunlap@xxxxxxxxxxxxx>
Date: Thu, 17 Sep 2009 10:43:09 +0100
Cc: "xen-devel@xxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxx>, Kouya Shimura <kouya@xxxxxxxxxxxxxx>
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Keir Fraser wrote:
On 17/09/2009 02:26, "Kouya Shimura" <kouya@xxxxxxxxxxxxxx> wrote:

real 0m2.343s
user 0m0.040s
sys 0m0.030s

real 2m25.741s
user 0m0.090s
sys 0m0.020s

I'm about to lose my patience with it. :-)
Can you control it by a boot parameter? (ex. "pod_debug=nnn")

Yeah, that's too slow for our normal debug build. I think we'll revert the
patch -- noone would ever enable it, unless maybe if helping George track
down a PoD bug.
Hmm... my only concern is that the assumption seems like something which might easily change, with no one realizing that they'd broken the assumption, and the codepath not being tested since most OSS users probably won't be using PoD.

Hmm, perhaps we could wrap it with an if() statement checking if there are any outstanding PoD entries? The assumption only really matters when PoD is in use.

Alternately, a separate #define for PoD debug might be useful, so we can easily turn on all these options when we need to.

-George

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