From: "Jan Beulich" <JBeulich@suse.com>
To: Andres Lagar Cavilla <andres@lagarcavilla.org>
Cc: xen-devel <xen-devel@lists.xenproject.org>, Tim Deegan <tim@xen.org>
Subject: Re: heavy P2M lock contention on guest HPET counter reads
Date: Fri, 01 Aug 2014 07:38:02 +0100 [thread overview]
Message-ID: <53DB51EA020000780002843D@mail.emea.novell.com> (raw)
In-Reply-To: <CADzFZPt_-pk7pNthzeK0+OoSn1yWpdr5jHzezGwE3ZU-=2A9Hg@mail.gmail.com>
>>> On 30.07.14 at 20:15, <andres@lagarcavilla.org> wrote:
> Having said that, I don't know off the top of my head that is obviously
> correct to shortcut the p2m lookup for msix table and iommu. I think so,
> but...
All internal MMIO ranges are what you'd call "positively decoded" on
real hardware, i.e. they ought to supersede any other address
decoding rules anyway. Since they're also not associated with
possibly varying MFNs, the P2M lookup on them is simply pointless,
and short-circuiting them is imo at once making better guarantees
towards consistent behavior.
Jan
next prev parent reply other threads:[~2014-08-01 6:38 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-07-30 10:08 heavy P2M lock contention on guest HPET counter reads Jan Beulich
2014-07-30 10:29 ` Andrew Cooper
2014-07-30 10:46 ` Jan Beulich
2014-07-30 14:22 ` Jan Beulich
2014-07-30 18:15 ` Andres Lagar Cavilla
2014-08-01 6:38 ` Jan Beulich [this message]
2014-08-02 2:33 ` Andres Lagar Cavilla
2014-08-04 7:00 ` Jan Beulich
2014-08-08 2:46 ` Andres Lagar Cavilla
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