From: Keir Fraser <Keir.Fraser@cl.cam.ac.uk>
To: Jan Beulich <jbeulich@novell.com>
Cc: xen-devel@lists.xensource.com
Subject: Re: [PATCH] x86 linux: prevent halted VCPUs from eating up CPU bandwidth
Date: Mon, 29 May 2006 15:59:25 +0100 [thread overview]
Message-ID: <73269221f5db8876639054dfebfa5617@cl.cam.ac.uk> (raw)
In-Reply-To: <447B22B4.76E4.0078.0@novell.com>
On 29 May 2006, at 15:35, Jan Beulich wrote:
> Since there was no reply to an earlier inquiry regarding this, here's
> a patch.
>
> Signed-off-by: Jan Beulich <jbeulich@novell.com>
safe_halt() should simply be HYPERVISOR_block() -- the hypercall
implicitly reenables interrupt delivery for the calling VCPU, so no
need to call __sti() explicitly.
halt() is a bit trickier -- given that it is executed (as far as I can
tell) only in contexts where the CPU has reached "end of life" (it's
crashed, or offlined, or shut down for some other reason) it might make
sense to define halt() as VCPUOP_down. Or, just in case it is used in
places with interrupts still enabled, where the CPU may have a future:
#define halt() (irqs_disabled() ? HYPERVISOR_vcpu_op(VCPUOP_down) :
HYPERVISOR_block())
-- Keir
next prev parent reply other threads:[~2006-05-29 14:59 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-05-29 14:35 [PATCH] x86 linux: prevent halted VCPUs from eating up CPU bandwidth Jan Beulich
2006-05-29 14:59 ` Keir Fraser [this message]
2006-05-30 8:11 ` Jan Beulich
2006-05-30 8:49 ` Keir Fraser
2006-05-30 9:21 ` Jan Beulich
2006-05-30 9:30 ` Keir Fraser
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