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RE: [Xen-ia64-devel]PATCH] Remove duplicate check is_running_on_xen

To: "Alex Williamson" <alex.williamson@xxxxxx>
Subject: RE: [Xen-ia64-devel]PATCH] Remove duplicate check is_running_on_xen
From: "Xu, Anthony" <anthony.xu@xxxxxxxxx>
Date: Wed, 17 Jan 2007 16:46:27 +0800
Cc: xen-ia64-devel <xen-ia64-devel@xxxxxxxxxxxxxxxxxxx>
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Thread-topic: [Xen-ia64-devel]PATCH] Remove duplicate check is_running_on_xen
This is updated one.


Alex Williamson write on 2007年1月17日 11:10:
> On Wed, 2007-01-17 at 10:17 +0800, Xu, Anthony wrote:
>> There are two duplicate checks as below, so there are two way to
>> eliminate one check. 
>> 1. eliminate check in xen_get_tpr, then xen_get_tpr will never be
>>      called on bare metal, but it's a little perfomance impact, due
>> to there is another switch inside __ia64_getreg. 
>> 2. eliminate check in xen_ia64_getreg, then xen_get_tpr will be
>>    called both on para platform or bare metal, it can produce better
>> performance than option 1. so I prefer this. 
>    Is the performance difference actually measurable?  I suspect it's
> effectively within the noise of any benchmark.  I prefer option 1
> because the leaf function when running on bare metal is the same as
> the native kernel, so we're not duplicating code.  Thanks,
>       Alex

Attachment: remove_duplicate_check2.patch
Description: remove_duplicate_check2.patch

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