From: Charlie Jenkins <charlie@rivosinc.com>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: Paul Walmsley <paul.walmsley@sifive.com>,
Palmer Dabbelt <palmer@dabbelt.com>,
Huacai Chen <chenhuacai@kernel.org>,
WANG Xuerui <kernel@xen0n.name>,
Peter Zijlstra <peterz@infradead.org>,
Andy Lutomirski <luto@kernel.org>,
Alexandre Ghiti <alexghiti@rivosinc.com>,
linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org,
loongarch@lists.linux.dev
Subject: Re: [PATCH v5 4/4] entry: Inline syscall_exit_to_user_mode()
Date: Sat, 8 Mar 2025 16:08:24 -0800 [thread overview]
Message-ID: <Z8zb-L8bFMh_YHxO@ghost> (raw)
In-Reply-To: <87senn3dh1.ffs@tglx>
On Sat, Mar 08, 2025 at 01:37:30PM +0100, Thomas Gleixner wrote:
> On Wed, Mar 05 2025 at 16:43, Charlie Jenkins wrote:
> > Architectures using the generic entry code can be optimized by having
> > syscall_exit_to_user_mode inlined.
>
> That's a pretty handwavy claim. What's the actual benefit in numbers?
I put the numbers in the cover letter! Here is the data I gathered:
Testing was done with the byte-unixbench [1] syscall benchmark (which
calls getpid) and QEMU. On riscv I measured a 7.09246% improvement, on
x86 a 2.98843% improvement, on loongarch a 6.07954% improvement, and on
s390 a 11.1328% improvement.
The Intel bot also reported "kernel test robot noticed a 1.9%
improvement of stress-ng.seek.ops_per_sec" [2]
- Charlie
>
> Thanks,
>
> tglx
next prev parent reply other threads:[~2025-03-09 0:08 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-03-06 0:43 [PATCH v5 0/4] entry: Move ret_from_fork() to C and inline syscall_exit_to_user_mode() Charlie Jenkins
2025-03-06 0:43 ` [PATCH v5 1/4] riscv: entry: Convert ret_from_fork() to C Charlie Jenkins
2025-03-06 0:43 ` [PATCH v5 2/4] riscv: entry: Split ret_from_fork() into user and kernel Charlie Jenkins
2025-03-10 9:51 ` Alexandre Ghiti
2025-03-06 0:43 ` [PATCH v5 3/4] LoongArch: entry: Migrate ret_from_fork() to C Charlie Jenkins
2025-03-06 0:43 ` [PATCH v5 4/4] entry: Inline syscall_exit_to_user_mode() Charlie Jenkins
2025-03-08 12:37 ` Thomas Gleixner
2025-03-09 0:08 ` Charlie Jenkins [this message]
2025-03-09 8:23 ` Thomas Gleixner
2025-03-10 4:34 ` Charlie Jenkins
2025-03-10 9:58 ` Alexandre Ghiti
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