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[2a00:1028:838d:271e:8e3b:4aff:fe4c:a100]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-49048f70f55sm76151265e9.17.2026.05.25.10.33.12 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 25 May 2026 10:33:13 -0700 (PDT) Message-ID: Date: Mon, 25 May 2026 19:33:12 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2] genksyms: Support arm64 CRC32 hardware acceleration1~ To: Wentao Guan Cc: linux-kbuild , linux-kernel , linux-modules , masahiroy References: <5d1b8b13-d590-497d-9185-609494135348@suse.com> <20260525080229.1570905-1-guanwentao@uniontech.com> <26c47a0e-7a9b-473a-818d-455e68476dd1@suse.com> Content-Language: en-US From: Petr Pavlu In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 5/25/26 3:41 PM, Wentao Guan wrote: >> On 5/25/26 10:02 AM, Wentao Guan wrote: >>>> Additionally, many distributions already switched to gendwarfksyms last >>>> year. Unless someone provides a good reason to keep genksyms around, >>>> I expect it will be deprecated soon and eventually removed. It would be >>>> more valuable to show whether the same optimization is worthwhile for >>>> gendwarfksyms. >>> I see gendwarfksyms use crc32 from , which from zlib1g-dev and zlib1g. >> >> Ah, I forgot about this, so gendwarfksyms should already be well >> optimized. I think that is the most important thing. > > Which way do you prefer? There are two ways now: > 1. this work, > 2. import zlib like gendwarfksyms and remove the huge crctab, > but need make sure any arch do not cause performance regression? > (Assert the user libs precompile with +crc32 is right?) > I do some early tests show that: > 1) zlib in x86 fast than genksym software > 2) zlib in arm64 debian precompile slow than genksym software(crc32 not in armv8) > 3) zlib in arm64 recompile with +crc32 same speed with genksyms hardware I think it would be useful to first have more data showing that the CRC calculation in genksyms is a hot path and contributes significantly to the overall kernel build time. -- Thanks, Petr