From: Catalin Marinas <catalin.marinas@arm.com>
To: Yeoreum Yun <yeoreum.yun@arm.com>
Cc: Will Deacon <will@kernel.org>,
broonie@kernel.org, maz@kernel.org, oliver.upton@linux.dev,
joey.gouly@arm.com, james.morse@arm.com, ardb@kernel.org,
scott@os.amperecomputing.com, suzuki.poulose@arm.com,
yuzenghui@huawei.com, mark.rutland@arm.com,
linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v7 RESEND 5/6] arm64: futex: small optimisation for __llsc_futex_atomic_set()
Date: Fri, 12 Sep 2025 17:36:20 +0100 [thread overview]
Message-ID: <aMRMBEdro1YJ5RLW@arm.com> (raw)
In-Reply-To: <aML2fwGfeubY6HgA@e129823.arm.com>
On Thu, Sep 11, 2025 at 05:19:11PM +0100, Yeoreum Yun wrote:
> > > +static __always_inline int
> > > +__llsc_futex_atomic_set(int oparg, u32 __user *uaddr, int *oval)
[...]
> > Hmm, I'm really not sure this is worthwhile. I doubt the "optimisation"
> > actually does anything and adding a whole new block of asm just for the
> > SET case isn't much of an improvement on the maintainability side, either.
>
> TBH, I had the same question, but I thought this code seems to modify
> freqenetly, I decide even a small optimisation -- reduce one instruction
> only.
>
> But I don't have strong opinion for this patch.
> If it's not good for maintainability perspective,
> This patch can be dropped.
I'd drop it for now unless you can show some performance benefits
(unlikely).
--
Catalin
next prev parent reply other threads:[~2025-09-12 16:36 UTC|newest]
Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-08-16 15:19 [PATCH RESEND v7 0/6] support FEAT_LSUI and apply it on futex atomic ops Yeoreum Yun
2025-08-16 15:19 ` [PATCH RESEND v7 1/6] arm64: cpufeature: add FEAT_LSUI Yeoreum Yun
2025-09-12 16:12 ` Catalin Marinas
2025-08-16 15:19 ` [PATCH RESEND v7 2/6] KVM: arm64: expose FEAT_LSUI to guest Yeoreum Yun
2025-09-12 16:25 ` Catalin Marinas
2025-08-16 15:19 ` [PATCH RESEND v7 3/6] arm64: Kconfig: add LSUI Kconfig Yeoreum Yun
2025-09-12 16:24 ` Catalin Marinas
2025-09-15 10:42 ` Yeoreum Yun
2025-09-15 11:32 ` Will Deacon
2025-09-15 11:41 ` Yeoreum Yun
2025-08-16 15:19 ` [PATCH RESEND v7 4/6] arm64: futex: refactor futex atomic operation Yeoreum Yun
2025-09-11 15:38 ` Will Deacon
2025-09-11 16:04 ` Yeoreum Yun
2025-09-12 16:44 ` Catalin Marinas
2025-09-12 17:01 ` Catalin Marinas
2025-09-15 10:39 ` Yeoreum Yun
2025-09-12 16:53 ` Catalin Marinas
2025-09-15 10:32 ` Yeoreum Yun
2025-09-15 19:40 ` Catalin Marinas
2025-09-15 20:35 ` Will Deacon
2025-09-16 7:02 ` Catalin Marinas
2025-09-16 9:15 ` Yeoreum Yun
2025-09-16 9:24 ` Yeoreum Yun
2025-09-16 10:02 ` Yeoreum Yun
2025-09-16 10:16 ` Will Deacon
2025-09-16 12:50 ` Yeoreum Yun
2025-09-17 9:32 ` Yeoreum Yun
2025-09-16 12:47 ` Mark Rutland
2025-09-16 13:27 ` Yeoreum Yun
2025-09-16 13:45 ` Mark Rutland
2025-09-16 13:58 ` Yeoreum Yun
2025-09-16 14:07 ` Mark Rutland
2025-09-16 14:15 ` Yeoreum Yun
2025-09-15 22:34 ` Yeoreum Yun
2025-09-16 12:53 ` Catalin Marinas
2025-08-16 15:19 ` [PATCH v7 RESEND 5/6] arm64: futex: small optimisation for __llsc_futex_atomic_set() Yeoreum Yun
2025-09-11 15:28 ` Will Deacon
2025-09-11 16:19 ` Yeoreum Yun
2025-09-12 16:36 ` Catalin Marinas [this message]
2025-09-15 10:41 ` Yeoreum Yun
2025-08-16 15:19 ` [PATCH RESEND v7 6/6] arm64: futex: support futex with FEAT_LSUI Yeoreum Yun
2025-09-11 15:22 ` Will Deacon
2025-09-11 16:45 ` Yeoreum Yun
2025-09-12 17:16 ` Catalin Marinas
2025-09-15 9:15 ` Yeoreum Yun
2025-09-12 17:09 ` Catalin Marinas
2025-09-15 8:24 ` Yeoreum Yun
2025-09-01 10:06 ` [PATCH RESEND v7 0/6] support FEAT_LSUI and apply it on futex atomic ops Yeoreum Yun
2025-09-11 15:09 ` Will Deacon
2025-09-11 16:22 ` Catalin Marinas
2025-09-15 20:37 ` Will Deacon
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