From: Bradley Morgan <brads@mainlining.org>
To: Linus Torvalds <torvalds@linux-foundation.org>,
"Paul E. McKenney" <paulmck@kernel.org>
Cc: rcu@vger.kernel.org, linux-kernel@vger.kernel.org,
kernel-team@meta.com,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
Boqun Feng <boqun@kernel.org>,
Steven Rostedt <rostedt@goodmis.org>,
lkmm@lists.linux.dev, Zqiang <qiang.zhang@linux.dev>,
Wang Lian <lianux.mm@gmail.com>,
Kunwu Chan <kunwu.chan@gmail.com>,
Nicholas Piggin <npiggin@gmail.com>,
Michael Ellerman <mpe@ellerman.id.au>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
Will Deacon <will@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Alan Stern <stern@rowland.harvard.edu>,
John Stultz <jstultz@google.com>,
Andrew Morton <akpm@linux-foundation.org>,
Frederic Weisbecker <frederic@kernel.org>,
Joel Fernandes <joel@joelfernandes.org>,
Josh Triplett <josh@joshtriplett.org>,
Uladzislau Rezki <urezki@gmail.com>,
Lai Jiangshan <jiangshanlai@gmail.com>,
Zqiang <qiang.zhang1211@gmail.com>,
Ingo Molnar <mingo@redhat.com>, Waiman Long <longman@redhat.com>,
Mark Rutland <mark.rutland@arm.com>,
Thomas Gleixner <tglx@linutronix.de>,
Vlastimil Babka <vbabka@suse.cz>,
maged.michael@gmail.com, Mateusz Guzik <mjguzik@gmail.com>,
Jonas Oberhauser <jonas.oberhauser@huaweicloud.com>,
linux-mm@kvack.org
Subject: Re: [PATCH 01/28] hazptr: Implement Hazard Pointers
Date: Sat, 19 Sep 2026 17:34:47 +0100 [thread overview]
Message-ID: <6B1FC39D-6EB0-433A-8E49-E5EFC9379AD7@mainlining.org> (raw)
In-Reply-To: <CAHk-=wj9knmxXD01=top1DQ9_aqrN2a3kpWRS5DQv6QLwLOztg@mail.gmail.com>
On 19 September 2026 17:30:26 BST, Linus Torvalds
<torvalds@linux-foundation.org> wrote:
>On Fri, 18 Sept 2026 at 17:01, Paul E. McKenney <paulmck@kernel.org>
>wrote:
>>
>> Its main benefit over RCU is that it allows fast reclaim of
>> HP-protected pointers without needing to wait for a grace period.
>
>So last time I looked at this was some time ago, but the thing I was
>missing then seems to still be missing: actual real numbers.
>
>And no, I most *definitely* do not mean the pointless "do this in a tight
>loop".
>
>That's just garbage. Honestly, when I see those numbers it just makes
>me go "I don't want to merge things that even mention this kind of
>stupid load". It's worse than irrelevant - it's an actively
>misleading.
>
>So I want to see a real load where this is actually visible not a
>"loop a billion times on a hot-cache thing that doesn't do anything".
I wanna be a fanboy so bad here but I need to breathe and say something
technical
I think hazard pointers are good, what test do YOU suggest we do here?
Once I get that PowerPC grant I'm happy to run it.
God I wanted to be a fanboy and say omg Linus hi, but I'm sure I'll be
flamed, sigh. Sigh.
>
> Linus
>
--- Thanks!
"I'm not a very positive person" - Linus torvalds
next prev parent reply other threads:[~2026-09-19 16:35 UTC|newest]
Thread overview: 53+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-18 23:59 [PATCH RFC v3 0/28] Simple hazard-pointer implementation and torture tests Paul E. McKenney
2026-09-19 0:00 ` [PATCH 01/28] hazptr: Implement Hazard Pointers Paul E. McKenney
2026-09-19 11:12 ` Bradley Morgan
2026-09-19 16:30 ` Linus Torvalds
2026-09-19 16:34 ` Bradley Morgan [this message]
2026-09-19 17:00 ` Linus Torvalds
2026-09-19 17:09 ` Mathieu Desnoyers
2026-09-19 18:09 ` Boqun Feng
2026-09-19 17:19 ` Mathieu Desnoyers
2026-09-19 18:18 ` Paul E. McKenney
2026-09-19 23:58 ` Bradley Morgan
2026-09-19 16:41 ` Bradley Morgan
2026-09-19 17:56 ` Paul E. McKenney
2026-09-19 0:00 ` [PATCH 02/28] hazptr: Add refscale test Paul E. McKenney
2026-09-19 0:00 ` [PATCH 03/28] torture: Add a hazptrtorture.c torture test Paul E. McKenney
2026-09-19 0:00 ` [PATCH 04/28] hazptrtorture: Add testing of on-stack hazptr_ctx structures Paul E. McKenney
2026-09-19 0:00 ` [PATCH 05/28] hazptrtorture: Add microsecond-scale sleep in readers Paul E. McKenney
2026-09-19 0:00 ` [PATCH 06/28] hazptrtorture: Enable system-independent CPU overcommit Paul E. McKenney
2026-09-19 0:00 ` [PATCH 07/28] torture: Add a stutter_will_wait() function Paul E. McKenney
2026-09-19 0:00 ` [PATCH 08/28] hazptrtorture: Use mnemonic local variables for context information Paul E. McKenney
2026-09-19 0:00 ` [PATCH 09/28] hazptrtorture: Split hazptr_torture_reader_tail() from hazptr_torture_reader() Paul E. McKenney
2026-09-19 0:00 ` [PATCH 10/28] hazptrtorture: Add kthread to release deferred hazard pointers Paul E. McKenney
2026-09-19 0:00 ` [PATCH 11/28] hazptrtorture: Defer release of " Paul E. McKenney
2026-09-19 0:00 ` [PATCH 12/28] hazptrtorture: Add irq_acquire to acquire hazptr from irq Paul E. McKenney
2026-09-19 0:00 ` [PATCH 13/28] hazptrtorture: Use task_state_to_char() for task-state reporting Paul E. McKenney
2026-09-19 0:00 ` [PATCH 14/28] hazptrtorture: Pass hazptr_pending to hazptr_torture_reader_tail() Paul E. McKenney
2026-09-19 0:00 ` [PATCH 15/28] hazptrtorture: Add the ability to disable the writer kthread Paul E. McKenney
2026-09-19 0:00 ` [PATCH 16/28] hazptrtorture: Add irq_release to release hazptr from irq Paul E. McKenney
2026-09-19 0:00 ` [PATCH 17/28] hazptrtorture: Accumulate operation statistics Paul E. McKenney
2026-09-19 0:00 ` [PATCH 18/28] doc: Add hazptrtorture module parameters Paul E. McKenney
2026-09-19 0:00 ` [PATCH 19/28] hazptr: Permit detaching hazard pointers from contexts Paul E. McKenney
2026-09-19 11:42 ` Boqun Feng
2026-09-19 11:43 ` Boqun Feng
2026-09-19 0:00 ` [PATCH 20/28] hazptrtorture: Detach deferred and IPIed hazard pointers Paul E. McKenney
2026-09-19 0:00 ` [PATCH 21/28] hazptr: Introduce CONFIG_HAZPTR_DEBUG misuse detection Paul E. McKenney
2026-09-19 0:00 ` [PATCH 22/28] hazptrtorture: Fix hazptr ownership issue Paul E. McKenney
2026-09-19 0:00 ` [PATCH 23/28] hazptrtorture: Enable CONFIG_HAZPTR_DEBUG Paul E. McKenney
2026-09-19 0:00 ` [PATCH 24/28] hazptr: Upgrade kernel-doc headers Paul E. McKenney
2026-09-19 0:00 ` [PATCH 25/28] hazptrtorture: Fix inverted sleep condition in do_pending kthread Paul E. McKenney
2026-09-19 0:00 ` [PATCH 26/28] hazptr: Implement two-phase wildcard scan Paul E. McKenney
2026-09-19 13:28 ` Boqun Feng
2026-09-20 12:46 ` Mathieu Desnoyers
2026-09-20 15:55 ` Boqun Feng
2026-09-25 19:08 ` Mathieu Desnoyers
2026-09-20 14:46 ` Gary Guo
2026-09-20 15:44 ` Mathieu Desnoyers
2026-09-20 15:57 ` Gary Guo
2026-09-25 19:19 ` Mathieu Desnoyers
2026-09-25 20:17 ` Gary Guo
2026-09-25 20:18 ` Mathieu Desnoyers
2026-09-19 0:00 ` [PATCH 27/28] hazptr: handle NULL address in hazptr_detach Paul E. McKenney
2026-09-19 0:00 ` [PATCH 28/28] torture.sh: Add hazptr torturing Paul E. McKenney
2026-09-19 11:18 ` Bradley Morgan
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=6B1FC39D-6EB0-433A-8E49-E5EFC9379AD7@mainlining.org \
--to=brads@mainlining.org \
--cc=akpm@linux-foundation.org \
--cc=bigeasy@linutronix.de \
--cc=boqun@kernel.org \
--cc=frederic@kernel.org \
--cc=gregkh@linuxfoundation.org \
--cc=jiangshanlai@gmail.com \
--cc=joel@joelfernandes.org \
--cc=jonas.oberhauser@huaweicloud.com \
--cc=josh@joshtriplett.org \
--cc=jstultz@google.com \
--cc=kernel-team@meta.com \
--cc=kunwu.chan@gmail.com \
--cc=lianux.mm@gmail.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=lkmm@lists.linux.dev \
--cc=longman@redhat.com \
--cc=maged.michael@gmail.com \
--cc=mark.rutland@arm.com \
--cc=mathieu.desnoyers@efficios.com \
--cc=mingo@redhat.com \
--cc=mjguzik@gmail.com \
--cc=mpe@ellerman.id.au \
--cc=npiggin@gmail.com \
--cc=paulmck@kernel.org \
--cc=peterz@infradead.org \
--cc=qiang.zhang1211@gmail.com \
--cc=qiang.zhang@linux.dev \
--cc=rcu@vger.kernel.org \
--cc=rostedt@goodmis.org \
--cc=stern@rowland.harvard.edu \
--cc=tglx@linutronix.de \
--cc=torvalds@linux-foundation.org \
--cc=urezki@gmail.com \
--cc=vbabka@suse.cz \
--cc=will@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
all inboxes | Powered by JetHome®