From: Shivappa Vikas <vikas.shivappa@intel.com>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: Shivappa Vikas <vikas.shivappa@intel.com>,
Vikas Shivappa <vikas.shivappa@linux.intel.com>,
x86@kernel.org, linux-kernel@vger.kernel.org, hpa@zytor.com,
peterz@infradead.org, "Shankar,
Ravi V" <ravi.v.shankar@intel.com>,
tony.luck@intel.com, "Yu, Fenghua" <fenghua.yu@intel.com>
Subject: Re: [PATCH 13/21] x86/intel_rdt/cqm: Add cpus file support
Date: Thu, 13 Jul 2017 11:37:22 -0700 (PDT) [thread overview]
Message-ID: <alpine.DEB.2.10.1707131134260.31299@vshiva-Udesk> (raw)
In-Reply-To: <alpine.DEB.2.20.1707070822550.1871@nanos>
On Thu, 6 Jul 2017, Thomas Gleixner wrote:
> On Thu, 6 Jul 2017, Shivappa Vikas wrote:
>> On Sun, 2 Jul 2017, Thomas Gleixner wrote:
>>>> + /* Check whether cpus belong to parent ctrl group */
>>>> + cpumask_andnot(tmpmask, newmask, &pr->cpu_mask);
>>>> + if (cpumask_weight(tmpmask)) {
>>>> + ret = -EINVAL;
>>>> + goto out;
>>>> + }
>>>> +
>>>> + /* Check whether cpus are dropped from this group */
>>>> + cpumask_andnot(tmpmask, &rdtgrp->cpu_mask, newmask);
>>>> + if (cpumask_weight(tmpmask)) {
>>>> + /* Give any dropped cpus to parent rdtgroup */
>>>> + cpumask_or(&pr->cpu_mask, &pr->cpu_mask, tmpmask);
>>>
>>> This does not make any sense. The check above verifies that all cpus in
>>> newmask belong to the parent->cpu_mask. If they don't then you return
>>> -EINVAL, but here you give them back to parent->cpu_mask. How is that
>>> supposed to work? You never get into this code path!
>>
>> The parent->cpu_mask always is the parent->cpus_valid_mask if i understand
>> right. With monitor group, the cpu is present is always present in "one"
>> ctrl_mon group and one mon_group. And the mon group can have only cpus in its
>> parent. May be it needs a comment? (its explaind in the documentation patch).
>
> Sigh, the code needs to be written in a way that it is halfways obvious
> what's going on.
>
>> # mkdir /sys/fs/resctrl/p1
>> # mkdir /sys/fs/resctrl/p1/mon_groups/m1
>> # echo 5-10 > /sys/fs/resctr/p1/cpus_list
>> Say p1 has RMID 2
>> cpus 5-10 have RMID 2
>
> So what you say, is that parent is always the resource control group
> itself.
>
> Can we please have a proper distinction in the code? I tripped over that
> ambigiousities several times.
>
> The normal meaning of parent->child relations is that both have the same
> type. While this is the case at the implementation detail level (both are
> type struct rdtgroup), from a conceptual level they are different:
>
> parent is a resource group and child is a monitoring group
>
> That should be expressed in the code, at the very least by variable naming,
> so it becomes immediately clear that this operates on two different
> entities.
>
> The proper solution is to have different data types or at least embedd the
> monitoring bits in a seperate entity inside of struct rdtgroup.
Yes they are conceptually different. There were data which were
specific to monitoring only but they share a lot of data. So I was still
thinking whats best but kept a type which seperates them both. But the
monitoring only data seems like only the 'parent' so we can embed the monitoring
bits in a seperate struct (The parent is initialized for ctrl_mon group but
never really used).
Thanks,
Vikas
next prev parent reply other threads:[~2017-07-13 18:35 UTC|newest]
Thread overview: 65+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-06-26 18:55 [PATCH V1 00/21] x86/cqm3: Resctrl based cqm Vikas Shivappa
2017-06-26 18:55 ` [PATCH 01/21] x86/perf/cqm: Wipe out perf " Vikas Shivappa
2017-06-26 18:55 ` [PATCH 02/21] x86/intel_rdt: Fix memory leak during mount Vikas Shivappa
2017-06-30 19:24 ` [tip:x86/urgent] x86/intel_rdt: Fix memory leak on mount failure tip-bot for Vikas Shivappa
2017-06-26 18:55 ` [PATCH 03/21] x86/intel_rdt/cqm: Documentation for resctrl based RDT Monitoring Vikas Shivappa
2017-06-26 18:55 ` [PATCH 04/21] x86/intel_rdt: Introduce a common compile option for RDT Vikas Shivappa
2017-06-26 18:55 ` [PATCH 05/21] x86/intel_rdt: Change file names to accommodate RDT monitor code Vikas Shivappa
2017-06-26 18:55 ` [PATCH 06/21] x86/intel_rdt: Cleanup namespace to support RDT monitoring Vikas Shivappa
2017-06-26 18:55 ` [PATCH 07/21] x86/intel_rdt/cqm: Add RDT monitoring initialization Vikas Shivappa
2017-07-02 9:14 ` Thomas Gleixner
2017-07-06 21:07 ` Shivappa Vikas
2017-06-26 18:55 ` [PATCH 08/21] x86/intel_rdt/cqm: Add RMID(Resource monitoring ID) management Vikas Shivappa
2017-07-02 10:05 ` Thomas Gleixner
2017-07-03 9:55 ` Thomas Gleixner
2017-07-05 15:34 ` Peter Zijlstra
2017-07-05 17:25 ` Thomas Gleixner
2017-07-11 23:54 ` Shivappa Vikas
2017-07-12 20:14 ` Thomas Gleixner
2017-07-05 17:59 ` Tony Luck
2017-07-06 6:51 ` Thomas Gleixner
2017-06-26 18:55 ` [PATCH 09/21] x86/intel_rdt: Simplify info and base file lists Vikas Shivappa
2017-07-02 10:09 ` Thomas Gleixner
2017-07-06 21:09 ` Shivappa Vikas
2017-06-26 18:55 ` [PATCH 10/21] x86/intel_rdt/cqm: Add info files for RDT monitoring Vikas Shivappa
2017-06-26 18:55 ` [PATCH 11/21] x86/intel_rdt/cqm: Add mkdir support " Vikas Shivappa
2017-07-02 10:58 ` Thomas Gleixner
2017-07-06 21:23 ` Shivappa Vikas
2017-06-26 18:55 ` [PATCH 12/21] x86/intel_rdt/cqm: Add tasks file support Vikas Shivappa
2017-07-02 11:01 ` Thomas Gleixner
2017-07-06 21:25 ` Shivappa Vikas
2017-06-26 18:56 ` [PATCH 13/21] x86/intel_rdt/cqm: Add cpus " Vikas Shivappa
2017-07-02 11:11 ` Thomas Gleixner
2017-07-06 21:26 ` Shivappa Vikas
2017-07-02 12:29 ` Thomas Gleixner
2017-07-06 21:42 ` Shivappa Vikas
2017-07-07 6:44 ` Thomas Gleixner
2017-07-13 18:37 ` Shivappa Vikas [this message]
2017-07-13 22:09 ` Shivappa Vikas
2017-06-26 18:56 ` [PATCH 14/21] x86/intel_rdt/cqm: Add mon_data Vikas Shivappa
2017-07-02 12:43 ` Thomas Gleixner
2017-07-06 21:48 ` Shivappa Vikas
2017-07-07 6:22 ` Thomas Gleixner
2017-07-11 21:17 ` Shivappa Vikas
2017-07-11 21:37 ` Luck, Tony
2017-06-26 18:56 ` [PATCH 15/21] x86/intel_rdt/cqm: Add rmdir support Vikas Shivappa
2017-07-02 13:16 ` Thomas Gleixner
2017-07-06 21:49 ` Shivappa Vikas
2017-06-26 18:56 ` [PATCH 16/21] x86/intel_rdt/cqm: Add mount,umount support Vikas Shivappa
2017-07-02 13:22 ` Thomas Gleixner
2017-07-06 21:58 ` Shivappa Vikas
2017-06-26 18:56 ` [PATCH 17/21] x86/intel_rdt/cqm: Add sched_in support Vikas Shivappa
2017-07-02 13:37 ` Thomas Gleixner
2017-07-06 23:35 ` Shivappa Vikas
2017-06-26 18:56 ` [PATCH 18/21] x86/intel_rdt/cqm: Add hotcpu support Vikas Shivappa
2017-06-26 18:56 ` [PATCH 19/21] x86/intel_rdt/mbm: Basic counting of MBM events (total and local) Vikas Shivappa
2017-07-02 13:46 ` Thomas Gleixner
2017-07-06 23:39 ` Shivappa Vikas
2017-07-07 6:47 ` Thomas Gleixner
2017-06-26 18:56 ` [PATCH 20/21] x86/intel_rdt/mbm: Add mbm counter initialization Vikas Shivappa
2017-06-26 18:56 ` [PATCH 21/21] x86/intel_rdt/mbm: Handle counter overflow Vikas Shivappa
2017-07-02 13:57 ` Thomas Gleixner
2017-07-06 23:53 ` Shivappa Vikas
2017-07-07 6:50 ` Thomas Gleixner
2017-07-10 17:54 ` Luck, Tony
2017-07-11 15:22 ` Thomas Gleixner
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=alpine.DEB.2.10.1707131134260.31299@vshiva-Udesk \
--to=vikas.shivappa@intel.com \
--cc=fenghua.yu@intel.com \
--cc=hpa@zytor.com \
--cc=linux-kernel@vger.kernel.org \
--cc=peterz@infradead.org \
--cc=ravi.v.shankar@intel.com \
--cc=tglx@linutronix.de \
--cc=tony.luck@intel.com \
--cc=vikas.shivappa@linux.intel.com \
--cc=x86@kernel.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).