From: Dietmar Eggemann <dietmar.eggemann@arm.com>
To: Beata Michalska <beata.michalska@arm.com>
Cc: linux-kernel@vger.kernel.org, peterz@infradead.org,
mingo@redhat.com, juri.lelli@redhat.com,
vincent.guittot@linaro.org, valentin.schneider@arm.com,
corbet@lwn.net, rdunlap@infradead.org, linux-doc@vger.kernel.org
Subject: Re: [PATCH v5 2/3] sched/topology: Rework CPU capacity asymmetry detection
Date: Tue, 25 May 2021 13:59:30 +0200 [thread overview]
Message-ID: <8f00a2d4-2443-9656-2d51-6c5798fda552@arm.com> (raw)
In-Reply-To: <20210525093039.GA31871@e120325.cambridge.arm.com>
On 25/05/2021 11:30, Beata Michalska wrote:
> On Tue, May 25, 2021 at 10:25:36AM +0200, Dietmar Eggemann wrote:
>> On 24/05/2021 12:16, Beata Michalska wrote:
[...]
>>> @@ -1266,6 +1266,112 @@ static void init_sched_groups_capacity(int cpu, struct sched_domain *sd)
>>> update_group_capacity(sd, cpu);
>>> }
>>>
>>> +/**
>>> + * Asymmetric CPU capacity bits
>>> + */
>>> +struct asym_cap_data {
>>> + struct list_head link;
>>> + unsigned long capacity;
>>> + struct cpumask *cpu_mask;
>>
>> Not sure if this has been discussed already but shouldn't the flexible
>> array members` approach known from struct sched_group, struct
>> sched_domain or struct em_perf_domain be used here?
>> IIRC the last time this has been discussed in this thread:
>> https://lkml.kernel.org/r/20200910054203.525420-2-aubrey.li@intel.com
>>
> If I got right the discussion you have pointed to, it was about using
> cpumask_var_t which is not the case here. I do not mind moving the code
> to use the array but I am not sure if this changes much. Looking at the
> code changes to support that (to_cpumask namely) it was introduced for
> cases where cpumask_var_t was not appropriate, which again isn't the case
> here.
Yeah, it was more about using `flexible array members` or allocating the
cpumask separately.
Looks like you're using some kind of a mixed approach:
(1) struct asym_cap_data {
...
struct cpumask *cpu_mask;
(2) entry = kzalloc(sizeof(*entry) + cpumask_size(), GFP_KERNEL);
(3) entry->cpu_mask = (struct cpumask *)((char *)entry +
sizeof(*entry));
(4) cpumask_intersects(foo, entry->cpu_mask)
E.g. struct em_perf_domain has
(1) struct em_perf_domain {
...
unsigned long cpus[];
(2) like yours
(3) is not needed.
(4) cpumask_copy(em_span_cpus(pd), foo)
with #define em_span_cpus(em) (to_cpumask((em)->cpus))
IMHO, it's better to keep this approach aligned between the different
data structures.
next prev parent reply other threads:[~2021-05-25 11:59 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-24 10:16 [PATCH v5 0/3] Rework CPU capacity asymmetry detection Beata Michalska
2021-05-24 10:16 ` [PATCH v5 1/3] sched/core: Introduce SD_ASYM_CPUCAPACITY_FULL sched_domain flag Beata Michalska
2021-05-24 10:16 ` [PATCH v5 2/3] sched/topology: Rework CPU capacity asymmetry detection Beata Michalska
2021-05-24 18:01 ` Valentin Schneider
2021-05-24 22:55 ` Beata Michalska
2021-05-24 23:19 ` Beata Michalska
2021-05-25 9:53 ` Valentin Schneider
2021-05-25 10:29 ` Beata Michalska
2021-05-26 9:52 ` Dietmar Eggemann
2021-05-26 12:15 ` Beata Michalska
2021-05-26 12:51 ` Beata Michalska
2021-05-26 18:17 ` Dietmar Eggemann
2021-05-26 21:40 ` Beata Michalska
2021-05-27 15:08 ` Dietmar Eggemann
2021-05-27 17:07 ` Beata Michalska
2021-06-02 17:17 ` Dietmar Eggemann
2021-06-02 19:48 ` Beata Michalska
2021-06-03 9:09 ` Dietmar Eggemann
2021-06-03 9:24 ` Beata Michalska
2021-05-26 18:17 ` Dietmar Eggemann
2021-05-26 21:43 ` Beata Michalska
2021-05-27 7:03 ` Peter Zijlstra
2021-05-27 12:22 ` Dietmar Eggemann
2021-05-27 12:32 ` Beata Michalska
2021-05-25 8:25 ` Dietmar Eggemann
2021-05-25 9:30 ` Beata Michalska
2021-05-25 11:59 ` Dietmar Eggemann [this message]
2021-05-25 14:04 ` Beata Michalska
2021-05-24 10:16 ` [PATCH v5 3/3] sched/doc: Update the CPU capacity asymmetry bits Beata Michalska
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=8f00a2d4-2443-9656-2d51-6c5798fda552@arm.com \
--to=dietmar.eggemann@arm.com \
--cc=beata.michalska@arm.com \
--cc=corbet@lwn.net \
--cc=juri.lelli@redhat.com \
--cc=linux-doc@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@redhat.com \
--cc=peterz@infradead.org \
--cc=rdunlap@infradead.org \
--cc=valentin.schneider@arm.com \
--cc=vincent.guittot@linaro.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).