From: "Roger Pau Monn�" <roger.pau@citrix.com>
To: Yi Sun <yi.y.sun@linux.intel.com>
Cc: kevin.tian@intel.com, wei.liu2@citrix.com,
andrew.cooper3@citrix.com, dario.faggioli@citrix.com,
ian.jackson@eu.citrix.com, julien.grall@arm.com,
mengxu@cis.upenn.edu, jbeulich@suse.com,
chao.p.peng@linux.intel.com, xen-devel@lists.xenproject.org
Subject: Re: [PATCH v2 07/15] x86: implement set value flow for MBA
Date: Thu, 31 Aug 2017 11:19:21 +0100 [thread overview]
Message-ID: <20170831101921.orh6aksx4ul73akm@MacBook-Pro-de-Roger.local> (raw)
In-Reply-To: <20170831101007.GK23665@yi.y.sun>
On Thu, Aug 31, 2017 at 06:10:07PM +0800, Yi Sun wrote:
> On 17-08-31 10:30:37, Roger Pau Monn� wrote:
> > On Thu, Aug 31, 2017 at 05:13:08PM +0800, Yi Sun wrote:
> > > On 17-08-31 09:30:47, Roger Pau Monn� wrote:
> > > > On Thu, Aug 31, 2017 at 10:20:10AM +0800, Yi Sun wrote:
> > > > > On 17-08-30 09:31:04, Roger Pau Monn� wrote:
> > > > > > On Thu, Aug 24, 2017 at 09:14:41AM +0800, Yi Sun wrote:
> > > > > Even user inputs a value that does not fulfill HW requirement, HW can handle it.
> > > > > So, we do not need return error to user. Otherwise, user needs to know details
> > > > > of MBA.
> > > > >
> > > > > But the issue here is how we get the actual value and show it to user. There are
> > > > > two ways to do that:
> > > > > 1. When setting value, check and change it to valid one and save it to our cache.
> > > >
> > > > Instead of performing those checks manually, why not simply write the
> > > > value and read it back to see the one the hardware has actually
> > > > chosen (and cache it)?
> > > >
> > > So, I guess you prefer optioin 2, right? If so, do we need check if input value
> > > is valid? I see above comment that you prefer to return an error and leave the
> > > decision to user.
> >
> > Yes, I think so. Is reading the MSR in any performance critical path?
> > Or it's just used by the user-space tools?
> >
> Just used by user-space tools.
Then doing a MSR read each time doesn't seem that bad IMHO (it's not a
critical path anyway).
Roger.
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next prev parent reply other threads:[~2017-08-31 10:19 UTC|newest]
Thread overview: 64+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-08-24 1:14 [PATCH v2 00/15] Enable Memory Bandwidth Allocation in Xen Yi Sun
2017-08-24 1:14 ` [PATCH v2 01/15] docs: create Memory Bandwidth Allocation (MBA) feature document Yi Sun
2017-08-29 11:46 ` Roger Pau Monné
2017-08-30 5:20 ` Yi Sun
2017-08-30 7:42 ` Roger Pau Monn�
2017-08-24 1:14 ` [PATCH v2 02/15] Rename PSR sysctl/domctl interfaces and xsm policy to make them be general Yi Sun
2017-08-29 12:00 ` Roger Pau Monné
2017-08-30 5:23 ` Yi Sun
2017-08-30 7:47 ` Roger Pau Monn�
2017-08-30 8:14 ` Yi Sun
2017-08-24 1:14 ` [PATCH v2 03/15] x86: rename 'cbm_type' to 'psr_val_type' to make it general Yi Sun
2017-08-29 12:15 ` Roger Pau Monné
2017-08-30 5:47 ` Yi Sun
2017-08-30 7:51 ` Roger Pau Monn�
2017-08-30 8:14 ` Yi Sun
2017-08-24 1:14 ` [PATCH v2 04/15] x86: implement data structure and CPU init flow for MBA Yi Sun
2017-08-29 13:44 ` Roger Pau Monné
2017-08-29 13:58 ` Jan Beulich
2017-08-30 6:07 ` Yi Sun
2017-08-30 5:31 ` Yi Sun
2017-08-30 7:55 ` Roger Pau Monn�
2017-08-30 8:19 ` Yi Sun
2017-08-30 8:45 ` Jan Beulich
2017-08-24 1:14 ` [PATCH v2 05/15] x86: implement get hw info " Yi Sun
2017-08-29 15:01 ` Roger Pau Monné
2017-08-30 5:33 ` Yi Sun
2017-08-24 1:14 ` [PATCH v2 06/15] x86: implement get value interface " Yi Sun
2017-08-29 15:04 ` Roger Pau Monné
2017-08-24 1:14 ` [PATCH v2 07/15] x86: implement set value flow " Yi Sun
2017-08-30 8:31 ` Roger Pau Monné
2017-08-31 2:20 ` Yi Sun
2017-08-31 8:30 ` Roger Pau Monn�
2017-08-31 9:13 ` Yi Sun
2017-08-31 9:30 ` Roger Pau Monn�
2017-08-31 10:10 ` Yi Sun
2017-08-31 10:19 ` Roger Pau Monn� [this message]
2017-08-24 1:14 ` [PATCH v2 08/15] tools: create general interfaces to support psr allocation features Yi Sun
2017-08-30 8:42 ` Roger Pau Monné
2017-08-31 2:38 ` Yi Sun
2017-08-31 8:37 ` Roger Pau Monn�
2017-09-04 2:09 ` Yi Sun
2017-09-04 8:43 ` Wei Liu
2017-08-24 1:14 ` [PATCH v2 09/15] tools: implement the new libxc get hw info interface Yi Sun
2017-08-30 8:58 ` Roger Pau Monné
2017-08-31 3:05 ` Yi Sun
2017-08-24 1:14 ` [PATCH v2 10/15] tools: implement the new libxl " Yi Sun
2017-08-30 9:15 ` Roger Pau Monné
2017-08-31 3:16 ` Yi Sun
2017-08-31 8:40 ` Roger Pau Monn�
2017-08-31 9:19 ` Yi Sun
2017-08-31 9:32 ` Roger Pau Monn�
2017-08-31 10:11 ` Yi Sun
2017-08-24 1:14 ` [PATCH v2 11/15] tools: implement the new xl " Yi Sun
2017-08-30 9:23 ` Roger Pau Monné
2017-08-31 5:57 ` Yi Sun
2017-08-31 8:43 ` Roger Pau Monn�
2017-08-31 9:24 ` Yi Sun
2017-08-24 1:14 ` [PATCH v2 12/15] tools: rename 'xc_psr_cat_type' to 'xc_psr_val_type' Yi Sun
2017-08-30 9:24 ` Roger Pau Monné
2017-08-24 1:14 ` [PATCH v2 13/15] tools: implement new generic get value interface and MBA get value command Yi Sun
2017-08-24 1:14 ` [PATCH v2 14/15] tools: implement new generic set value interface and MBA set " Yi Sun
2017-08-30 9:47 ` Roger Pau Monné
2017-08-31 5:58 ` Yi Sun
2017-08-24 1:14 ` [PATCH v2 15/15] docs: add MBA description in docs Yi Sun
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