From: Andrew Cooper <andrew.cooper3@citrix.com>
To: Doug Goldstein <cardoe@cardoe.com>, Jan Beulich <JBeulich@suse.com>
Cc: xen-devel@lists.xen.org
Subject: Re: [PATCH 2/9] x86/mtrr: drop mtrr_if indirection
Date: Thu, 18 Aug 2016 10:40:31 +0100 [thread overview]
Message-ID: <7dc19465-5ab1-1bfa-cfe5-c1f7a81dfb97@citrix.com> (raw)
In-Reply-To: <e0a5bb74-5131-cebf-4ff8-19f61f813108@cardoe.com>
On 18/08/16 02:59, Doug Goldstein wrote:
> On 8/17/16 7:49 AM, Jan Beulich wrote:
>>>>> On 17.08.16 at 01:28, <cardoe@cardoe.com> wrote:
>>> There can only ever be one mtrr_if now and that is the generic
>>> implementation
>> This is only true when taking into consideration that cpu_has_mtrr
>> is #define-d to 1 right now. I'm not sure that's actually a good
>> assumption (especially when think about running Xen itself
>> virtualized, or possibly adding a mode of operation where no MTRRs
>> are to be used). But if we want to keep it that way, then I'd suggest
>> this patch should include removing cpu_has_mtrr (which will then
>> show to the reviewers that the checks of mtrr_if against NULL
>> indeed are dead code.
> Sure I can remove cpu_has_mtrr that would certainly make it cleaner. Is
> it ok with you and Andrew to make the assumption that we'll always have
> MTRRs (until the day we don't like you described)?
Please don't remove cpu_has_mtrr. I plan to make better use of it with
the future plan to move PV guests into a PVH container.
In such a case, the PVH container won't want/need MTRRs, and we will get
better performance by not having them available.
~Andrew
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next prev parent reply other threads:[~2016-08-18 9:40 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-08-16 23:28 [PATCH 0/9] x86/mtrr: basic cleanups Doug Goldstein
2016-08-16 23:28 ` [PATCH 1/9] x86/mtrr: prefix fns with mtrr and drop static Doug Goldstein
2016-08-17 12:36 ` Jan Beulich
2016-08-18 1:38 ` Doug Goldstein
2016-08-18 9:34 ` Jan Beulich
2016-08-16 23:28 ` [PATCH 2/9] x86/mtrr: drop mtrr_if indirection Doug Goldstein
2016-08-17 12:49 ` Jan Beulich
2016-08-18 1:59 ` Doug Goldstein
2016-08-18 9:37 ` Jan Beulich
2016-08-18 9:40 ` Andrew Cooper [this message]
2016-08-16 23:28 ` [PATCH 3/9] x86/mtrr: drop have_wrcomb() wrapper Doug Goldstein
2016-08-17 12:52 ` Jan Beulich
2016-08-16 23:28 ` [PATCH 4/9] x86/mtrr: drop unnecessary use_intel() macro Doug Goldstein
2016-08-17 12:53 ` Jan Beulich
2016-08-16 23:28 ` [PATCH 5/9] x86/mtrr: drop unused is_cpu() macro Doug Goldstein
2016-08-17 13:18 ` Jan Beulich
2016-08-16 23:28 ` [PATCH 6/9] x86/mtrr: drop unused mtrr_ops struct Doug Goldstein
2016-08-17 13:19 ` Jan Beulich
2016-08-16 23:28 ` [PATCH 7/9] x86/mtrr: drop unused positive_have_wrcomb() Doug Goldstein
2016-08-17 13:21 ` Jan Beulich
2016-08-16 23:28 ` [PATCH 8/9] x86/mtrr: drop unused func prototypes and struct Doug Goldstein
2016-08-17 13:23 ` Jan Beulich
2016-08-16 23:28 ` [PATCH 9/9] x86/mtrr: use stdbool instead of int + define Doug Goldstein
2016-08-17 13:29 ` Jan Beulich
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