From: Peter Zijlstra <peterz@infradead.org>
To: Thomas Gleixner <tglx@kernel.org>
Cc: "Breno Leitao" <leitao@debian.org>,
"Ingo Molnar" <mingo@redhat.com>,
"Darren Hart" <dvhart@infradead.org>,
"Davidlohr Bueso" <dave@stgolabs.net>,
"André Almeida" <andrealmeid@igalia.com>,
linux-kernel@vger.kernel.org, puranjay@kernel.org,
rmikey@meta.com, stuclar@meta.com, namhyung@kernel.org,
kernel-team@meta.com
Subject: Re: [PATCH RFC] futex: avoid false sharing between hb->chain and the bucket lock
Date: Wed, 10 Jun 2026 13:25:46 +0200 [thread overview]
Message-ID: <20260610112546.GE187714@noisy.programming.kicks-ass.net> (raw)
In-Reply-To: <87h5na3ait.ffs@fw13>
On Wed, Jun 10, 2026 at 01:22:34PM +0200, Thomas Gleixner wrote:
> On Tue, Jun 09 2026 at 22:18, Peter Zijlstra wrote:
> > On Tue, Jun 09, 2026 at 10:11:17PM +0200, Peter Zijlstra wrote:
> >> Anyway, how does something like the below work for you? It's a total
> >> hack job, but it (sorta) builds and runs.
> >>
> >
> > Please use this one, I spotted a silly bug.
>
> So I ran this on two machines.
>
> SKL dual socket 112 threads:
>
> Baseline Patched
>
> shared (16k) 1571857 1641435 + 4.4%
> autosize (512) 646390 903371 +39.7%
> -b 256 464395 587014 +26.4%
> -b 512 715687 995943 +39.2%
> -b 1024 995085 1396328 +40.3%
> -b 2048 1293114 1668395 +29.0%
> -b 4096 2124438 2240228 + 5.5%
>
> Zen3 dual socket 256 threads:
>
> Baseline Patched
>
> shared (16k) 1275840 1381279 + 8.2%
> autosize (512) 1252745 1482179 +18.3%
> -b 256 856274 955455 +11.5%
> -b 512 1267490 1544010 +21.8%
> -b 1024 1424013 1625424 +14.1%
> -b 2048 1505181 1669342 +10.9%
> -b 4096 1465993 1688932 +15.2%
I suppose that means I'd better go make it prettier and survive
randconfig :-)
next prev parent reply other threads:[~2026-06-10 11:25 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-06-05 16:53 Breno Leitao
2026-06-09 10:46 ` Peter Zijlstra
2026-06-09 15:28 ` Breno Leitao
2026-06-09 20:11 ` Peter Zijlstra
2026-06-09 20:18 ` Peter Zijlstra
2026-06-10 11:22 ` Thomas Gleixner
2026-06-10 11:25 ` Peter Zijlstra [this message]
2026-06-10 13:55 ` Peter Zijlstra
2026-06-12 7:11 ` [tip: locking/core] futex: Optimize futex hash bucket access patterns tip-bot2 for Peter Zijlstra
2026-06-12 8:13 ` Breno Leitao
2026-06-10 13:56 ` [PATCH RFC] futex: avoid false sharing between hb->chain and the bucket lock Breno Leitao
2026-06-23 10:30 ` Breno Leitao
2026-06-09 20:16 ` Thomas Gleixner
2026-06-09 20:23 ` Peter Zijlstra
2026-06-09 20:25 ` Peter Zijlstra
2026-06-09 20:32 ` Thomas Gleixner
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