From: "Luck, Tony" <tony.luck@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, ravi.v.shankar@intel.com,
fenghua.yu@intel.com, andi.kleen@intel.com
Subject: Re: [PATCH 21/21] x86/intel_rdt/mbm: Handle counter overflow
Date: Mon, 10 Jul 2017 10:54:18 -0700 [thread overview]
Message-ID: <20170710175418.ghphbgunhswrravh@intel.com> (raw)
In-Reply-To: <alpine.DEB.2.20.1707070849430.1871@nanos>
On Fri, Jul 07, 2017 at 08:50:40AM +0200, Thomas Gleixner wrote:
> Aside of that, are you really serious about serializing the world and
> everything on a single global mutex?
It would be nice to not do that, but there are challenges. At
any instant someone else might run:
# rmdir /sys/fs/resctrl/{some_control_group}
and blow away the control group and all the monitor groups under
it.
Someone else might do:
# echo 0 > /sys/devices/system/cpu/cpu{N}/online
where "N" is the last online cpu in a domain, which will
blow away an rdt_domain structure and ask kernfs to remove
some monitor files from every monitor directory.
If we change how we handle rdt_domains to
1) Not delete them when last CPU goes away (and re-use them
if they come back)
2) Have a safe way to search rdt_resource.domains for a domain
that we know is there even though another may be in the middle
of being added
Then we could probably make:
$ cat /sys/fs/restrl/ ... /llc_occupancy
etc. not need to grab the mutex. We'd still need something
to protect against a cross processor interrupt geting in the
middle of the access to IA32_QM_EVTSEL/IA32_QM_CTR and for
MBM counters to serialize access to mbm_state ... but it would
be a lot finer granularity.
-Tony
next prev parent reply other threads:[~2017-07-10 17:54 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
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 [this message]
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=20170710175418.ghphbgunhswrravh@intel.com \
--to=tony.luck@intel.com \
--cc=andi.kleen@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=vikas.shivappa@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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.