From: Andrew Cooper <andrew.cooper3@citrix.com>
To: Jan Beulich <JBeulich@suse.com>
Cc: xen-devel <xen-devel@lists.xenproject.org>, Keir Fraser <keir@xen.org>
Subject: Re: [PATCH 0/2] make hypercall preemption checks consistent
Date: Tue, 4 Mar 2014 11:52:06 +0000 [thread overview]
Message-ID: <5315BE66.5030903@citrix.com> (raw)
In-Reply-To: <5315C5370200007800120CE4@nat28.tlf.novell.com>
On 04/03/14 11:21, Jan Beulich wrote:
> - never preempt on the first iteration (ensure forward progress)
> - never preempt on the last iteration (pointless/wasteful)
> - do cheap checks first
>
> 1: common: make hypercall preemption checks consistent
> 2: x86: make hypercall preemption checks consistent
>
> Signed-off-by: Jan Beulich <jbeulich@suse.com>
All in all, this is a good improvement over what is currently present.
However, given the overhead of creating continuations (particularly for
32bit HVM guests, which have been seen to unconditionally fail the
preemption check by the time the compat layer has run), some of these
operations would probably be better having more than a single guaranteed
operation.
~Andrew
next prev parent reply other threads:[~2014-03-04 11:52 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-03-04 11:21 [PATCH 0/2] make hypercall preemption checks consistent Jan Beulich
2014-03-04 11:24 ` [PATCH 1/2] common: " Jan Beulich
2014-03-04 11:29 ` Andrew Cooper
2014-03-04 11:26 ` [PATCH 2/2] x86: " Jan Beulich
2014-03-04 11:35 ` Andrew Cooper
2014-03-04 11:30 ` [PATCH 0/2] " Jan Beulich
2014-03-11 11:38 ` Ian Campbell
2014-03-04 11:46 ` Tim Deegan
2014-03-04 11:52 ` Andrew Cooper [this message]
2014-03-04 12:00 ` Jan Beulich
2014-03-04 12:10 ` David Vrabel
2014-03-04 13:06 ` Jan Beulich
2014-03-04 14:07 ` David Vrabel
2014-03-12 9:35 ` Ping: " Jan Beulich
2014-03-13 10:26 ` Keir Fraser
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