From: Keir Fraser <keir.fraser@eu.citrix.com>
To: Kaushik Kumar Ram <kaushik@rice.edu>
Cc: "xen-devel@lists.xensource.com" <xen-devel@lists.xensource.com>
Subject: Re: question on iommu _map_page
Date: Fri, 2 Jul 2010 08:13:41 +0100 [thread overview]
Message-ID: <C8535035.1945A%keir.fraser@eu.citrix.com> (raw)
In-Reply-To: <AA9F2A39-CD5B-4227-A011-242B6E3C8FE8@rice.edu>
On 02/07/2010 07:22, "Kaushik Kumar Ram" <kaushik@rice.edu> wrote:
>> See if xen-unstable:21597 works for you.
>
> Keir,
>
> I finally found some time to test your patch. While it seems to fix the
> problem, it *significantly* degrades performance.
> On running netperf, there is a 10X reduction in throughput to a guest VM. On
> profiling, I find a significant number of cycles
> being spent in mapcount(). In the current solution, the entire grant table is
> searched every time (right ?). The mapping info
> ought to be stored in some per-page location... for efficient access.
It needs to be a per-mapping-domain location. Like the VT-d pte itself.
Patches welcome.
-- Keir
next prev parent reply other threads:[~2010-07-02 7:13 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-05-27 20:37 question on iommu _map_page Kaushik Kumar Ram
2010-05-27 20:46 ` Keir Fraser
2010-05-27 20:59 ` Kaushik Kumar Ram
2010-05-28 8:08 ` Keir Fraser
2010-05-28 23:20 ` Kaushik Kumar Ram
2010-05-29 7:29 ` Keir Fraser
2010-05-29 8:08 ` Kaushik Kumar Ram
2010-06-10 21:59 ` Kaushik Kumar Ram
2010-06-11 8:32 ` Keir Fraser
2010-07-02 6:22 ` Kaushik Kumar Ram
2010-07-02 7:13 ` Keir Fraser [this message]
2010-07-02 10:41 ` Keir Fraser
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