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From: Andy Shevchenko <andriy.shevchenko@intel.com>
To: Feng Jiang <jiangfeng@kylinos.cn>
Cc: pjw@kernel.org, palmer@dabbelt.com, aou@eecs.berkeley.edu,
	alex@ghiti.fr, kees@kernel.org, andy@kernel.org,
	akpm@linux-foundation.org, ebiggers@kernel.org,
	martin.petersen@oracle.com, ardb@kernel.org,
	ajones@ventanamicro.com, conor.dooley@microchip.com,
	samuel.holland@sifive.com, linus.walleij@linaro.org,
	nathan@kernel.org, linux-riscv@lists.infradead.org,
	linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org
Subject: Re: [PATCH v2 00/14] riscv: optimize string functions and add kunit tests
Date: Tue, 13 Jan 2026 10:52:29 +0200	[thread overview]
Message-ID: <aWYHzYRdba03HSIH@smile.fi.intel.com> (raw)
In-Reply-To: <20260113082748.250916-1-jiangfeng@kylinos.cn>

On Tue, Jan 13, 2026 at 04:27:34PM +0800, Feng Jiang wrote:
> This series introduces optimized assembly implementations for strnlen,
> strchr, and strrchr on the RISC-V architecture. To support a rigorous
> verification process, the series also significantly expands the
> string_kunit test suite with both functional correctness tests and
> performance benchmarks.
> 
> The patchset is organized as follows:
> - Refactoring (Patches 1-4): Extract generic C implementations for
>   strlen, strnlen, strchr, and strrchr into exported __generic_* functions.
> - Correctness Testing (Patches 5-7): Extend string_kunit with detailed
>   functional tests for the target functions.
> - Performance Benchmarking (Patches 8-11): Add a benchmarking framework
>   to string_kunit to measure execution time across various string lengths.
> - RISC-V Optimizations (Patches 12-14): Provide the optimized assembly
>   implementations for the RISC-V architecture.

...

>         # string_test_strlen_bench: strlen performance (long, len: 2048, iters: 10000):
>         # string_test_strlen_bench:   arch-optimized: 14100 ns
>         # string_test_strlen_bench:   generic C:      35605600 ns
>         # string_test_strlen_bench:   speedup:        2525.21x

Doesn't sound right. I think you measured cache performance and not your algo.

-- 
With Best Regards,
Andy Shevchenko



WARNING: multiple messages have this Message-ID (diff)
From: Andy Shevchenko <andriy.shevchenko@intel.com>
To: Feng Jiang <jiangfeng@kylinos.cn>
Cc: pjw@kernel.org, palmer@dabbelt.com, aou@eecs.berkeley.edu,
	alex@ghiti.fr, kees@kernel.org, andy@kernel.org,
	akpm@linux-foundation.org, ebiggers@kernel.org,
	martin.petersen@oracle.com, ardb@kernel.org,
	ajones@ventanamicro.com, conor.dooley@microchip.com,
	samuel.holland@sifive.com, linus.walleij@linaro.org,
	nathan@kernel.org, linux-riscv@lists.infradead.org,
	linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org
Subject: Re: [PATCH v2 00/14] riscv: optimize string functions and add kunit tests
Date: Tue, 13 Jan 2026 10:52:29 +0200	[thread overview]
Message-ID: <aWYHzYRdba03HSIH@smile.fi.intel.com> (raw)
In-Reply-To: <20260113082748.250916-1-jiangfeng@kylinos.cn>

On Tue, Jan 13, 2026 at 04:27:34PM +0800, Feng Jiang wrote:
> This series introduces optimized assembly implementations for strnlen,
> strchr, and strrchr on the RISC-V architecture. To support a rigorous
> verification process, the series also significantly expands the
> string_kunit test suite with both functional correctness tests and
> performance benchmarks.
> 
> The patchset is organized as follows:
> - Refactoring (Patches 1-4): Extract generic C implementations for
>   strlen, strnlen, strchr, and strrchr into exported __generic_* functions.
> - Correctness Testing (Patches 5-7): Extend string_kunit with detailed
>   functional tests for the target functions.
> - Performance Benchmarking (Patches 8-11): Add a benchmarking framework
>   to string_kunit to measure execution time across various string lengths.
> - RISC-V Optimizations (Patches 12-14): Provide the optimized assembly
>   implementations for the RISC-V architecture.

...

>         # string_test_strlen_bench: strlen performance (long, len: 2048, iters: 10000):
>         # string_test_strlen_bench:   arch-optimized: 14100 ns
>         # string_test_strlen_bench:   generic C:      35605600 ns
>         # string_test_strlen_bench:   speedup:        2525.21x

Doesn't sound right. I think you measured cache performance and not your algo.

-- 
With Best Regards,
Andy Shevchenko



_______________________________________________
linux-riscv mailing list
linux-riscv@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-riscv

  parent reply	other threads:[~2026-01-13  8:52 UTC|newest]

Thread overview: 72+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-01-13  8:27 [PATCH v2 00/14] riscv: optimize string functions and add kunit tests Feng Jiang
2026-01-13  8:27 ` Feng Jiang
2026-01-13  8:27 ` [PATCH v2 01/14] lib/string: extract generic strlen() into __generic_strlen() Feng Jiang
2026-01-13  8:27   ` Feng Jiang
2026-01-13  8:33   ` Andy Shevchenko
2026-01-13  8:33     ` Andy Shevchenko
2026-01-14  0:01   ` Eric Biggers
2026-01-14  0:01     ` Eric Biggers
2026-01-14  1:41     ` Feng Jiang
2026-01-14  1:41       ` Feng Jiang
2026-01-14  7:07     ` Andy Shevchenko
2026-01-14  7:07       ` Andy Shevchenko
2026-01-14 10:10     ` David Laight
2026-01-14 10:10       ` David Laight
2026-01-15  6:50       ` Feng Jiang
2026-01-15  6:50         ` Feng Jiang
2026-01-15  6:55         ` Andy Shevchenko
2026-01-15  6:55           ` Andy Shevchenko
2026-01-13  8:27 ` [PATCH v2 02/14] lib/string: extract generic strnlen() into __generic_strnlen() Feng Jiang
2026-01-13  8:27   ` Feng Jiang
2026-01-13  8:27 ` [PATCH v2 03/14] lib/string: extract generic strchr() into __generic_strchr() Feng Jiang
2026-01-13  8:27   ` Feng Jiang
2026-01-13  8:27 ` [PATCH v2 04/14] lib/string: extract generic strrchr() into __generic_strrchr() Feng Jiang
2026-01-13  8:27   ` Feng Jiang
2026-01-13  8:27 ` [PATCH v2 05/14] lib/string_kunit: add correctness test for strlen Feng Jiang
2026-01-13  8:27   ` Feng Jiang
2026-01-13  8:27 ` [PATCH v2 06/14] lib/string_kunit: add correctness test for strnlen Feng Jiang
2026-01-13  8:27   ` Feng Jiang
2026-01-13  8:41   ` Andy Shevchenko
2026-01-13  8:41     ` Andy Shevchenko
2026-01-13  8:27 ` [PATCH v2 07/14] lib/string_kunit: add correctness test for strrchr() Feng Jiang
2026-01-13  8:27   ` Feng Jiang
2026-01-13  8:27 ` [PATCH v2 08/14] lib/string_kunit: add performance benchmark for strlen() Feng Jiang
2026-01-13  8:27   ` Feng Jiang
2026-01-13  8:46   ` Andy Shevchenko
2026-01-13  8:46     ` Andy Shevchenko
2026-01-14  6:14     ` Feng Jiang
2026-01-14  6:14       ` Feng Jiang
2026-01-14  7:04       ` Feng Jiang
2026-01-14  7:04         ` Feng Jiang
2026-01-14  7:21         ` Andy Shevchenko
2026-01-14  7:21           ` Andy Shevchenko
2026-01-14  8:05           ` Feng Jiang
2026-01-14  8:05             ` Feng Jiang
2026-01-14 10:21         ` David Laight
2026-01-14 10:21           ` David Laight
2026-01-15  6:24           ` Feng Jiang
2026-01-15  6:24             ` Feng Jiang
2026-01-15 10:40             ` David Laight
2026-01-15 10:40               ` David Laight
2026-01-18 11:11   ` kernel test robot
2026-01-18 11:11     ` kernel test robot
2026-01-13  8:27 ` [PATCH v2 09/14] lib/string_kunit: add performance benchmark for strnlen() Feng Jiang
2026-01-13  8:27   ` Feng Jiang
2026-01-13  8:27 ` [PATCH v2 10/14] lib/string_kunit: add performance benchmark for strchr() Feng Jiang
2026-01-13  8:27   ` Feng Jiang
2026-01-13  8:27 ` [PATCH v2 11/14] lib/string_kunit: add performance benchmark for strrchr() Feng Jiang
2026-01-13  8:27   ` Feng Jiang
2026-01-13  8:27 ` [PATCH v2 12/14] riscv: lib: add strnlen implementation Feng Jiang
2026-01-13  8:27   ` Feng Jiang
2026-01-13  8:48   ` Andy Shevchenko
2026-01-13  8:48     ` Andy Shevchenko
2026-01-13  8:27 ` [PATCH v2 13/14] riscv: lib: add strchr implementation Feng Jiang
2026-01-13  8:27   ` Feng Jiang
2026-01-13  8:27 ` [PATCH v2 14/14] riscv: lib: add strrchr implementation Feng Jiang
2026-01-13  8:27   ` Feng Jiang
2026-01-13  8:52 ` Andy Shevchenko [this message]
2026-01-13  8:52   ` [PATCH v2 00/14] riscv: optimize string functions and add kunit tests Andy Shevchenko
2026-01-15  4:43 ` Joel Stanley
2026-01-15  4:43   ` Joel Stanley
2026-01-19  9:24   ` Feng Jiang
2026-01-19  9:24     ` Feng Jiang

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