From: Keir Fraser <keir@xen.org>
To: "Zhang, Yang Z" <yang.z.zhang@intel.com>,
"xen-devel@lists.xensource.com" <xen-devel@lists.xensource.com>
Subject: Re: lock in vhpet
Date: Wed, 18 Apr 2012 09:29:07 +0100 [thread overview]
Message-ID: <CBB439E3.3E625%keir@xen.org> (raw)
In-Reply-To: <A9667DDFB95DB7438FA9D7D576C3D87E0DA169@SHSMSX101.ccr.corp.intel.com>
On 18/04/2012 08:55, "Zhang, Yang Z" <yang.z.zhang@intel.com> wrote:
>> If the HPET accesses are atomic on bare metal, we have to maintain that, even
>> if some guests have extra locking themselves. Also, in some cases Xen needs
>> locking to correctly maintain its own internal state regardless of what an
>> (untrusted) guest might do. So we cannot just get rid of the vhpet lock
>> everywhere. It's definitely not correct to do so. Optimising the hpet read
>> path
>> however, sounds okay. I agree the lock may not be needed on that specific
>> path.
>
> You are right.
> For this case, since the main access of hpet is to read the main counter, so I
> think the rwlock is a better choice.
I'll see if I can make a patch...
-- Keir
next prev parent reply other threads:[~2012-04-18 8:29 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-04-17 3:26 lock in vhpet Zhang, Yang Z
2012-04-17 7:27 ` Keir Fraser
2012-04-18 0:52 ` Zhang, Yang Z
2012-04-18 7:13 ` Keir Fraser
2012-04-18 7:55 ` Zhang, Yang Z
2012-04-18 8:29 ` Keir Fraser [this message]
2012-04-18 9:14 ` Keir Fraser
2012-04-18 9:30 ` Keir Fraser
2012-04-19 5:19 ` Zhang, Yang Z
2012-04-19 8:27 ` Tim Deegan
2012-04-19 8:47 ` Keir Fraser
2012-04-23 7:36 ` Zhang, Yang Z
2012-04-23 7:43 ` Jan Beulich
2012-04-23 8:15 ` Zhang, Yang Z
2012-04-23 8:22 ` Keir Fraser
2012-04-23 9:14 ` Tim Deegan
2012-04-23 15:26 ` Andres Lagar-Cavilla
2012-04-24 9:15 ` Tim Deegan
2012-04-24 13:28 ` Andres Lagar-Cavilla
2012-04-23 17:18 ` Andres Lagar-Cavilla
2012-04-24 8:58 ` Zhang, Yang Z
2012-04-24 9:16 ` Tim Deegan
2012-04-25 0:27 ` Zhang, Yang Z
2012-04-25 1:40 ` Andres Lagar-Cavilla
2012-04-25 1:48 ` Zhang, Yang Z
2012-04-25 2:31 ` Andres Lagar-Cavilla
2012-04-25 2:36 ` Zhang, Yang Z
2012-04-25 2:42 ` Andres Lagar-Cavilla
2012-04-25 3:12 ` Zhang, Yang Z
2012-04-25 3:34 ` Andres Lagar-Cavilla
2012-04-25 5:18 ` Zhang, Yang Z
2012-04-25 8:07 ` Jan Beulich
2012-04-26 21:25 ` Tim Deegan
2012-04-27 0:46 ` Zhang, Yang Z
2012-04-27 0:51 ` Andres Lagar-Cavilla
2012-04-27 1:24 ` Zhang, Yang Z
2012-04-27 8:36 ` Zhang, Yang Z
2012-04-27 3:02 ` Andres Lagar-Cavilla
2012-04-27 9:26 ` Tim Deegan
2012-04-27 14:17 ` Andres Lagar-Cavilla
2012-04-27 21:08 ` Andres Lagar-Cavilla
2012-05-16 11:36 ` Zhang, Yang Z
2012-05-16 12:36 ` Tim Deegan
2012-05-17 10:57 ` Tim Deegan
2012-05-28 6:54 ` Zhang, Yang Z
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