From: Keir Fraser <keir@xensource.com>
To: "Xu, Anthony" <anthony.xu@intel.com>
Cc: xen-devel@lists.xensource.com,
xen-ia64-devel <xen-ia64-devel@lists.xensource.com>
Subject: Re: Question about evtchn_callback reentry
Date: Mon, 18 Dec 2006 09:31:33 +0000 [thread overview]
Message-ID: <C1AC1075.5FF3%keir@xensource.com> (raw)
In-Reply-To: <51CFAB8CB6883745AE7B93B3E084EBE207DDA8@pdsmsx412.ccr.corp.intel.com>
On 18/12/06 5:28 am, "Xu, Anthony" <anthony.xu@intel.com> wrote:
> If there is no special handling, low privileged interrupt may
> "interrupt" high privileged interrupt.
There's no concept of privilege among event channels. Since Xen simply
allocates ExtInts to vectors in a round-robin manner, there is no meaningful
priority comparsion to be made between vectors anyway.
> BTW,
> I do see evtchn_callback reentry happen on IPF dom0, and that incur
> about 5% performance degradation
> with KB on VTI-domain compared to non_reentry.
KB == Keyboard?!
Reentry is allowed -- it shouldn't happen often unless the ISRs are really
long (bad) or we are hammering the interrupt line for some reason (bad).
-- Keir
next prev parent reply other threads:[~2006-12-18 9:31 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-12-18 5:28 [Xen-devel] Question about evtchn_callback reentry Xu, Anthony
2006-12-18 9:31 ` Keir Fraser [this message]
-- strict thread matches above, loose matches on Subject: below --
2006-12-18 9:53 Xu, Anthony
2006-12-18 11:24 ` Keir Fraser
2006-12-18 13:42 ` Keir Fraser
2006-12-20 3:03 [Xen-devel] " Xu, Anthony
2006-12-20 8:31 ` Keir Fraser
2006-12-20 10:08 Xu, Anthony
2006-12-20 10:31 ` Keir Fraser
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