linux-kernel - Re: [PATCH v3 8/8] riscv: lib: add strrchr implementation

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Message-ID: <aW8vhU-ECUIITPoh@smile.fi.intel.com>
Date: Tue, 20 Jan 2026 09:32:21 +0200
From: Andy Shevchenko <andriy.shevchenko@...el.com>
To: Feng Jiang <jiangfeng@...inos.cn>
Cc: pjw@...nel.org, palmer@...belt.com, aou@...s.berkeley.edu,
	alex@...ti.fr, akpm@...ux-foundation.org, kees@...nel.org,
	andy@...nel.org, ebiggers@...nel.org, martin.petersen@...cle.com,
	ardb@...nel.org, charlie@...osinc.com, conor.dooley@...rochip.com,
	ajones@...tanamicro.com, linus.walleij@...aro.org,
	nathan@...nel.org, linux-riscv@...ts.infradead.org,
	linux-kernel@...r.kernel.org, linux-hardening@...r.kernel.org,
	Joel Stanley <joel@....id.au>
Subject: Re: [PATCH v3 8/8] riscv: lib: add strrchr implementation

On Tue, Jan 20, 2026 at 02:58:52PM +0800, Feng Jiang wrote:
> Add an assembly implementation of strrchr() for RISC-V.
> 
> This implementation minimizes instruction count and avoids unnecessary
> memory access to the stack. The performance benefits are most visible
> on small workloads (1-16 bytes) where the architectural savings in
> function overhead outweigh the execution time of the scan loop.
> 
> Benchmark results (QEMU TCG, rv64):
>   Length | Original (MB/s) | Optimized (MB/s) | Improvement
>   -------|-----------------|------------------|------------
>   1 B    | 21              | 22               | +4.7%
>   7 B    | 116             | 122              | +5.1%
>   16 B   | 195             | 208              | +6.6%
>   512 B  | 388             | 399              | +2.8%
>   4096 B | 411             | 411              | +0.0%

> Suggested-by: Andy Shevchenko <andy@...nel.org>

Wrong tag.

-- 
With Best Regards,
Andy Shevchenko