From: Steven Rostedt <rostedt@goodmis.org>
To: Waiman Long <longman@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@redhat.com>,
Thomas Gleixner <tglx@linutronix.de>,
"H. Peter Anvin" <hpa@zytor.com>,
linux-kernel@vger.kernel.org,
Daniel Bristot de Oliveira <bristot@redhat.com>
Subject: Re: [RFC PATCH 0/7] locking/rtqspinlock: Realtime queued spinlocks
Date: Thu, 5 Jan 2017 13:50:20 -0500 [thread overview]
Message-ID: <20170105135020.40187dfa@gandalf.local.home> (raw)
In-Reply-To: <82624801-740f-9088-f6fb-7812f10fa146@redhat.com>
On Thu, 5 Jan 2017 12:07:21 -0500
Waiman Long <longman@redhat.com> wrote:
> I do make the assumption that spinlock critical sections are behaving
> well enough. Apparently, that is not a valid assumption. I sent these
> RFC patches out to see if it was an idea worth pursuing. If not, I can
> drop these patches. Anyway, thanks for the feedback.
Yes, the assumption is incorrect. There are places that can hold a spin
lock for several hundreds of microseconds. If you can't preempt them,
you'll never get below several hundreds of microseconds in latency.
And it would be hard to pick and choose (we already do this to decide
what can be a raw_spin_lock), because you need to audit all use cases
of a spin_lock as well as all the locks taken while holding that
spin_lock.
-- Steve
next prev parent reply other threads:[~2017-01-05 18:51 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-01-03 18:00 [RFC PATCH 0/7] locking/rtqspinlock: Realtime queued spinlocks Waiman Long
2017-01-03 18:00 ` [RFC PATCH 1/7] locking/spinlock: Remove the unused spin_lock_bh_nested API Waiman Long
2017-01-03 18:00 ` [RFC PATCH 2/7] locking/rtqspinlock: Introduce realtime queued spinlocks Waiman Long
2017-01-03 18:00 ` [RFC PATCH 3/7] locking/rtqspinlock: Use static RT priority when in interrupt context Waiman Long
2017-01-03 18:00 ` [RFC PATCH 4/7] locking/rtqspinlock: Override spin_lock_nested with special RT variants Waiman Long
2017-01-03 18:00 ` [RFC PATCH 5/7] locking/rtqspinlock: Handle priority boosting Waiman Long
2017-01-03 18:00 ` [RFC PATCH 6/7] locking/rtqspinlock: Voluntarily yield CPU when need_sched() Waiman Long
2017-01-04 10:07 ` Boqun Feng
2017-01-04 21:57 ` Waiman Long
2017-01-05 10:16 ` Daniel Bristot de Oliveira
2017-01-03 18:00 ` [RFC PATCH 7/7] locking/rtqspinlock: Enable collection of event counts Waiman Long
2017-01-04 12:49 ` [RFC PATCH 0/7] locking/rtqspinlock: Realtime queued spinlocks Peter Zijlstra
2017-01-04 15:25 ` Waiman Long
2017-01-04 15:55 ` Steven Rostedt
2017-01-04 20:02 ` Waiman Long
2017-01-05 18:43 ` Steven Rostedt
2017-01-05 9:26 ` Daniel Bristot de Oliveira
2017-01-05 9:44 ` Peter Zijlstra
2017-01-05 15:55 ` Waiman Long
2017-01-05 16:08 ` Peter Zijlstra
2017-01-05 17:07 ` Waiman Long
2017-01-05 18:50 ` Steven Rostedt [this message]
2017-01-05 19:24 ` Waiman Long
2017-01-05 18:05 ` Daniel Bristot de Oliveira
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=20170105135020.40187dfa@gandalf.local.home \
--to=rostedt@goodmis.org \
--cc=bristot@redhat.com \
--cc=hpa@zytor.com \
--cc=linux-kernel@vger.kernel.org \
--cc=longman@redhat.com \
--cc=mingo@redhat.com \
--cc=peterz@infradead.org \
--cc=tglx@linutronix.de \
/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).