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Re: [Xen-devel] [timer/ticks related] dom0 hang during boot on large 1TB

To: Jan Beulich <JBeulich@xxxxxxxxxx>
Subject: Re: [Xen-devel] [timer/ticks related] dom0 hang during boot on large 1TB system
From: Keir Fraser <keir.fraser@xxxxxxxxxxxxx>
Date: Fri, 18 Dec 2009 09:13:32 +0000
Cc: Kurt Hackel <kurt.hackel@xxxxxxxxxx>, Dan Magenheimer <dan.magenheimer@xxxxxxxxxx>, "Xen-devel@xxxxxxxxxxxxxxxxxxx" <Xen-devel@xxxxxxxxxxxxxxxxxxx>
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On 18/12/2009 08:42, "Jan Beulich" <JBeulich@xxxxxxxxxx> wrote:

>> This isn't really Xen time code, but unchanged Linux time code. I don't know
>> which tree you quoted the code from -- 2.6.18 has similar but not identical.
>> Anyway, I suggest try using the jiffy-comparison macros from
>> <linux/jiffies.h>: time_before(), time_after(), etc. These are designed to
>> work even when jiffies wraps. Feel free to send patch(es) for that, if you
>> test that out and it works okay.
> But regardless of that - shouldn't the page scrubbing really be a
> background operation these days, and as such be (relatively)
> performance neutral to the booting of Dom0?

We synchronously scrub free memory before starting dom0, and then
subsequently scrub memory only for dying domains. So I don't know what
scrubbing would be going on during dom0's boot-time calibrations, on any
version of Xen, actually.

 -- Keir

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