From: Jens Axboe <axboe@kernel.dk>
To: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
Matthew Wilcox <willy@infradead.org>
Cc: paulmck@kernel.org,
Linus Torvalds <torvalds@linux-foundation.org>,
Andrew Morton <akpm@linux-foundation.org>,
Peter Zijlstra <peterz@infradead.org>,
linux-kernel@vger.kernel.org, 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>, Boqun Feng <boqun.feng@gmail.com>,
Alan Stern <stern@rowland.harvard.edu>,
John Stultz <jstultz@google.com>,
Neeraj Upadhyay <Neeraj.Upadhyay@amd.com>,
Frederic Weisbecker <frederic@kernel.org>,
Joel Fernandes <joel@joelfernandes.org>,
Josh Triplett <josh@joshtriplett.org>,
Uladzislau Rezki <urezki@gmail.com>,
Steven Rostedt <rostedt@goodmis.org>,
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>,
rcu@vger.kernel.org, linux-mm@kvack.org, lkmm@lists.linux.dev
Subject: Re: [RFC PATCH 0/4] sched+mm: Track lazy active mm existence with hazard pointers
Date: Wed, 2 Oct 2024 09:58:28 -0600 [thread overview]
Message-ID: <579bdbbf-82a7-4330-9a5e-495d89befbac@kernel.dk> (raw)
In-Reply-To: <8a627fc7-cc62-40e6-ad28-c730d4a8f7d6@efficios.com>
[-- Attachment #1: Type: text/plain, Size: 2345 bytes --]
On 10/2/24 9:53 AM, Mathieu Desnoyers wrote:
> On 2024-10-02 17:36, Mathieu Desnoyers wrote:
>> On 2024-10-02 17:33, Matthew Wilcox wrote:
>>> On Wed, Oct 02, 2024 at 11:26:27AM -0400, Mathieu Desnoyers wrote:
>>>> On 2024-10-02 16:09, Paul E. McKenney wrote:
>>>>> On Tue, Oct 01, 2024 at 09:02:01PM -0400, Mathieu Desnoyers wrote:
>>>>>> Hazard pointers appear to be a good fit for replacing refcount based lazy
>>>>>> active mm tracking.
>>>>>>
>>>>>> Highlight:
>>>>>>
>>>>>> will-it-scale context_switch1_threads
>>>>>>
>>>>>> nr threads (-t) speedup
>>>>>> 24 +3%
>>>>>> 48 +12%
>>>>>> 96 +21%
>>>>>> 192 +28%
>>>>>
>>>>> Impressive!!!
>>>>>
>>>>> I have to ask... Any data for smaller numbers of CPUs?
>>>>
>>>> Sure, but they are far less exciting ;-)
>>>
>>> How many CPUs in the system under test?
>>
>> 2 sockets, 96-core per socket:
>>
>> CPU(s): 384
>> On-line CPU(s) list: 0-383
>> Vendor ID: AuthenticAMD
>> Model name: AMD EPYC 9654 96-Core Processor
>> CPU family: 25
>> Model: 17
>> Thread(s) per core: 2
>> Core(s) per socket: 96
>> Socket(s): 2
>> Stepping: 1
>> Frequency boost: enabled
>> CPU(s) scaling MHz: 68%
>> CPU max MHz: 3709.0000
>> CPU min MHz: 400.0000
>> BogoMIPS: 4800.00
>>
>> Note that Jens Axboe got even more impressive speedups testing this
>> on his 512-hw-thread EPYC [1] (390% speedup for 192 threads). I've
>> noticed I had schedstats and sched debug enabled in my config, so I'll have to re-run my tests.
>
> A quick re-run of the 128-thread case with schedstats and sched debug
> disabled still show around 26% speedup, similar to my prior numbers.
>
> I'm not sure why Jens has much better speedups on a similar system.
>
> I'm attaching my config in case someone spots anything obvious. Note
> that my BIOS is configured to show 24 NUMA nodes to the kernel (one
> NUMA node per core complex).
Here's my .config - note it's from the stock kernel run, which is why it
still has:
CONFIG_MMU_LAZY_TLB_REFCOUNT=y
set. Have the same numa configuration as you, just end up with 32 nodes
on this box.
--
Jens Axboe
[-- Attachment #2: r7625.config.gz --]
[-- Type: application/gzip, Size: 32934 bytes --]
next prev parent reply other threads:[~2024-10-02 15:58 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-10-02 1:02 [RFC PATCH 0/4] sched+mm: Track lazy active mm existence with hazard pointers Mathieu Desnoyers
2024-10-02 1:02 ` [RFC PATCH 1/4] compiler.h: Introduce ptr_eq() to preserve address dependency Mathieu Desnoyers
2024-10-03 0:08 ` Joel Fernandes
2024-10-03 14:19 ` Mathieu Desnoyers
2024-10-03 22:09 ` Joel Fernandes
2024-10-02 1:02 ` [RFC PATCH 2/4] Documentation: RCU: Refer to ptr_eq() Mathieu Desnoyers
2024-10-02 1:02 ` [RFC PATCH 3/4] hp: Implement Hazard Pointers Mathieu Desnoyers
2024-10-03 0:24 ` Boqun Feng
2024-10-03 13:30 ` Mathieu Desnoyers
2024-10-07 13:47 ` Boqun Feng
2024-10-07 14:52 ` Mathieu Desnoyers
2024-10-02 1:02 ` [RFC PATCH 4/4] sched+mm: Use hazard pointers to track lazy active mm existence Mathieu Desnoyers
2024-10-02 14:09 ` [RFC PATCH 0/4] sched+mm: Track lazy active mm existence with hazard pointers Paul E. McKenney
2024-10-02 15:26 ` Mathieu Desnoyers
2024-10-02 15:33 ` Matthew Wilcox
2024-10-02 15:36 ` Mathieu Desnoyers
2024-10-02 15:53 ` Mathieu Desnoyers
2024-10-02 15:58 ` Jens Axboe [this message]
2024-10-02 16:02 ` Mathieu Desnoyers
2024-10-02 16:14 ` Jens Axboe
2024-10-02 17:39 ` Linus Torvalds
2024-10-05 16:15 ` Peter Zijlstra
2024-10-05 16:56 ` Linus Torvalds
2024-10-07 7:06 ` Peter Zijlstra
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