From mboxrd@z Thu Jan  1 00:00:00 1970
From: Andrew Cooper <andrew.cooper3@citrix.com>
Subject: Re: [PATCH] iommu/quirk: disable shared EPT for
 Sandybridge and earlier processors.
Date: Fri, 28 Aug 2015 17:24:25 +0100
Message-ID: <55E08B39.5070300@citrix.com>
References: <1440776507-30218-1-git-send-email-anshul.makkar@citrix.com>
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To: "Anshul Makkar anshul.makkar"@citrix.com, xen-devel@lists.xen.org
Cc: yang.z.zhang@intel.com, kevin.tian@intel.com, anshulma <anshul.makkar@citrix.com>, jbeulich@suse.com
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On 28/08/15 16:41, "Anshul Makkar anshul.makkar"@citrix.com wrote:
> From: anshulma <anshul.makkar@citrix.com>
>
> Sandybridge or earlier processors don't have huge page support for
> IOTLB which leads to fallback on 4k pages and causes performance issues.
>
> Shared EPT will be disabled only if the user has not provided explicit
> choice on the command line.
>
> Signed-off-by: Anshul Makkar <anshul.makkar@citrix.com>

As a note concerning the performance issues, for some IO workloads, this
nets a 40% throughput improvement.

We did not observe any IO workloads which had a worse performance as a
result of disabling shared ept.

Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>

~Andrew