From: Jan Beulich <jbeulich@suse.com>
To: Dario Faggioli <dfaggioli@suse.com>
Cc: Juergen Gross <jgross@suse.com>,
xen-devel@lists.xenproject.org,
George Dunlap <george.dunlap@citrix.com>,
Andrew Cooper <andrew.cooper3@citrix.com>
Subject: Re: [PATCH 2/2] xen: credit2: limit the max number of CPUs in a runqueue
Date: Fri, 29 May 2020 11:58:51 +0200 [thread overview]
Message-ID: <bc005ca2-7bf2-3bb0-b9cd-0be05c914f3f@suse.com> (raw)
In-Reply-To: <a959e9e807dc1f832d151ab72f324f2c084c2461.camel@suse.com>
On 28.05.2020 16:55, Dario Faggioli wrote:
> On Wed, 2020-05-27 at 08:17 +0200, Jan Beulich wrote:
>> On 27.05.2020 00:00, Dario Faggioli wrote:
>>> Just in case, is there a
>>> way to identify them easily, like with a mask or something, in the
>>> code
>>> already?
>>
>> cpu_sibling_mask still gets used for both, so there's no mask
>> to use. As per set_cpu_sibling_map() you can look at
>> cpu_data[].compute_unit_id to tell, but that's of course x86-
>> specific (as is the entire compute unit concept).
>>
> Right. And thanks for the pointers.
>
> But then, what I am understanding by having a look there is that I
> indeed can use (again, appropriately wrapped) x86_num_siblings, for
> telling, in this function, whether a CPU has any, and if yes how many,
> HT (Intel) or CU (AMD) siblings in total, although some of them may
> currently be offline.
>
> Which means I will be treating HTs and CUs the same which, thinking
> more about it (and thinking actually to CUs, rather than to any cache
> sharing relationship), does make sense for this feature.
>
> Does this make sense, or am I missing or misinterpreting anything?
Well, it effectively answers the question I had raised: "What about HT
vs AMD Fam15's CUs? Do you want both to be treated the same here?"
Jan
next prev parent reply other threads:[~2020-05-29 9:59 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-29 17:36 [PATCH 0/2] xen: credit2: limit the number of CPUs per runqueue Dario Faggioli
2020-04-29 17:36 ` [PATCH 1/2] xen: credit2: factor cpu to runqueue matching in a function Dario Faggioli
2020-04-29 17:36 ` [PATCH 2/2] xen: credit2: limit the max number of CPUs in a runqueue Dario Faggioli
2020-04-30 6:45 ` Jan Beulich
2020-05-26 22:00 ` Dario Faggioli
2020-05-27 4:26 ` Jürgen Groß
2020-05-28 9:32 ` Dario Faggioli
2020-05-27 6:17 ` Jan Beulich
2020-05-28 14:55 ` Dario Faggioli
2020-05-29 9:58 ` Jan Beulich [this message]
2020-05-29 10:19 ` Dario Faggioli
2020-04-30 7:35 ` Jürgen Groß
2020-04-30 12:28 ` Dario Faggioli
2020-04-30 12:52 ` Jürgen Groß
2020-04-30 14:01 ` Dario Faggioli
2020-05-26 21:18 ` Dario Faggioli
2020-05-27 6:22 ` Jan Beulich
2020-05-28 9:36 ` Dario Faggioli
2020-05-29 11:46 ` [PATCH 0/2] xen: credit2: limit the number of CPUs per runqueue Dario Faggioli
2020-05-29 15:06 ` Dario Faggioli
2020-05-29 16:15 ` George Dunlap
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