From: Jisheng Zhang <jszhang@kernel•org>
To: Leo Yan <leo.yan@arm•com>
Cc: Catalin Marinas <catalin.marinas@arm•com>,
Will Deacon <will@kernel•org>, Arnd Bergmann <arnd@arndb•de>,
Thomas Gleixner <tglx@kernel•org>, Paul Walmsley <pjw@kernel•org>,
Palmer Dabbelt <palmer@dabbelt•com>,
Albert Ou <aou@eecs•berkeley.edu>,
Alexandre Ghiti <alex@ghiti•fr>, Guo Ren <guoren@kernel•org>,
linux-arm-kernel@lists•infradead.org,
linux-kernel@vger•kernel.org, linux-arch@vger•kernel.org,
linux-riscv@lists•infradead.org, linux-csky@vger•kernel.org
Subject: Re: [PATCH 3/3] arm64: use runtime constant to optimize handle_arch_irq access
Date: Wed, 25 Feb 2026 22:40:00 +0800 [thread overview]
Message-ID: <aZ8JwB2vJ98uab2V@xhacker> (raw)
In-Reply-To: <20260223091547.GJ136967@e132581.arm.com>
On Mon, Feb 23, 2026 at 09:15:47AM +0000, Leo Yan wrote:
> On Sat, Feb 21, 2026 at 08:14:17AM +0800, Jisheng Zhang wrote:
>
> [...]
>
> > On Fri, Feb 20, 2026 at 04:47:38PM +0000, Leo Yan wrote:
> > > On Fri, Feb 20, 2026 at 09:34:14PM +0800, Jisheng Zhang wrote:
> > >
> > > [...]
> > >
> > > > > > Run 3 iterations, and measures three metrics (messaging/pipe/seccomp)
> > > > > > and results in seconds. Less is better.
> > > > > >
> > > > > > +---------------------+--------+--------+--------+--------+
> > > > > > |Without change | run1 | run2 | run3 | avg |
> > > > > > +---------------------+--------+--------+--------+--------+
> > > > > > |messaging (sec) | 4.546 | 4.508 | 4.591 | 4.548 |
> > > > > > |pipe (sec) | 24.258 | 24.224 | 24.017 | 24.166 |
> > > > > > |seccomp-notify (sec) | 48.393 | 48.457 | 48.232 | 48.361 |
> > > > > > +---------------------+--------+--------+--------+--------+
> > > > > >
> > > > > > +---------------------+--------+--------+--------+--------+--------+
> > > > > > |With change | run1 | run2 | run3 | avg | diff |
> > > > > > +---------------------+--------+--------+--------+--------+--------+
> > > > > > |messaging (sec) | 4.493 | 4.523 | 4.556 | 4.524 | +0.52% |
> > > > > > |pipe (sec) | 23.159 | 23.702 | 28.649 | 25.170 | -4.15% |
> > > > >
> > > > > If you check the result, this result variance is abnormal, it means
> > > > > your OS is noiser.
> > > >
> > > > BTW: if you remove the abnormal run3 result, you'll find that the
> > > > benchmark is improved by ~3.5% on CA73:
> > > > (23.159 + 23.702) / 2 = 23.43
> > > > (24.258 + 24.224) / 2 = 24.24
> > > > (24.24 - 23.43)*100 / 23.43 = ~3.5
> > >
> > > TBH, I don't think we should subjectively select data. But I agree a
> >
> > The precondition of this is testing the benchmark properly. And I just
> > tried perf bench sched in noisy OS, I didn't get the similar abnormal
> > variance as you got, so I think your run3 result was CA53's result.
> > This isn't an apple-to-apple comparison.
>
> Not true. As said, I tested on CA73. I should say explicitly that I
> have hotplugged off CA53 CPUs and run test only on CA73 CPUs.
I tested on quad CA73 platform, I can reproduce the abnormal variance
as you got. This means the series may not alway improve performance
as I expected for *all* CPUs. So I'd like to drop it now.
>
> > If possible, could you plz test after forcing CA53 offline or test on
> > non big.little platform. Anyway, I will test CA73 next week too.
> >
> > > clean test env is important to avoid noise, and I also agree that the
> > > current results already show positive signals.
> > >
> > > Thanks,
> > > Leo
next prev parent reply other threads:[~2026-02-25 14:58 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-02-20 9:09 [PATCH 0/3] use runtime constant to optimize handle_arch_irq access Jisheng Zhang
2026-02-20 9:09 ` [PATCH 1/3] vmlinux.lds.h: add _handle_arch_irq RUNTIME_CONST section Jisheng Zhang
2026-02-24 2:01 ` Guo Ren
2026-02-20 9:09 ` [PATCH 2/3] genirq: use runtime constant to optimize handle_arch_irq access Jisheng Zhang
2026-02-22 22:06 ` Thomas Gleixner
2026-02-23 12:41 ` Jisheng Zhang
2026-02-23 13:11 ` Mark Rutland
2026-02-23 13:22 ` Jisheng Zhang
2026-02-23 13:55 ` Mark Rutland
2026-02-24 1:40 ` Guo Ren
2026-02-24 1:59 ` Guo Ren
2026-02-20 9:09 ` [PATCH 3/3] arm64: " Jisheng Zhang
2026-02-20 12:34 ` Leo Yan
2026-02-20 13:16 ` Jisheng Zhang
2026-02-20 13:34 ` Jisheng Zhang
2026-02-20 16:47 ` Leo Yan
2026-02-21 0:14 ` Jisheng Zhang
2026-02-23 9:15 ` Leo Yan
2026-02-25 14:40 ` Jisheng Zhang [this message]
2026-02-23 12:56 ` Mark Rutland
2026-02-23 12:58 ` Jisheng Zhang
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