From: Liu Yuan <yetiboy1230@gmail.com>
To: konrad.wilk@oracle.com
Cc: xen-devel@lists.xensource.com
Subject: Re: [PATCH] Simulates the MSIx table read operation
Date: Wed, 11 Aug 2010 00:04:15 +0800 [thread overview]
Message-ID: <AANLkTi=g3kjHvkngV9xyrKkJaUqpuYmTtsccsKMmr8y5@mail.gmail.com> (raw)
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>I am having a hard time understanding this. Is the issue here that
>read/write of the MSI-X table is being done in QEMU, and it is much
>better to do so in the hypervisor which traps already the mask/unmaks
>operation so that QEMU is not overwhelmed by having to do this?
Yes, having QEMU do this read operation,it needs much more CPU cycles
and longer latency.
[before patch]
read path: Guest -> Xen -> QEMU -> XEN -> Guest
[after patch]
read path: Guest -> Xen -> Guest
Xen traps all the MSIx table operation. And before this patch, only
mask/unmask is simulated in
Xen. With this patch applied, READ will be simulated and WRITE will
*still* be forwarded to QEMU.
>
>With this in patch in place, wouldn't QEMU still do the read operation?
No
Thanks,
Yuan
--
I am Multician, really
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next reply other threads:[~2010-08-10 16:04 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-08-10 16:04 Liu Yuan [this message]
-- strict thread matches above, loose matches on Subject: below --
2010-08-04 9:08 [PATCH] Simulates the MSIx table read operation Liu, Yuan B
2010-08-04 8:12 Liu, Yuan B
2010-08-04 2:36 Liu, Yuan B
2010-08-04 2:35 Liu, Yuan B
2010-08-06 15:01 ` Konrad Rzeszutek Wilk
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