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Mon, 21 Jul 2025 14:33:54 -0400 (EDT) From: Junio C Hamano To: Phillip Wood Cc: Ezekiel Newren via GitGitGadget , git@vger.kernel.org, Elijah Newren , Ezekiel Newren Subject: Re: [PATCH 0/7] RFC: Accelerate xdiff and begin its rustification In-Reply-To: <45ea5d1d-05dd-4f7a-bee5-ea3936d23d0a@gmail.com> (Phillip Wood's message of "Mon, 21 Jul 2025 11:14:38 +0100") References: <45ea5d1d-05dd-4f7a-bee5-ea3936d23d0a@gmail.com> Date: Mon, 21 Jul 2025 11:33:52 -0700 Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Precedence: bulk X-Mailing-List: git@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain Phillip Wood writes: > ... by 15%. Just over half of that seems to come from hoisting the > check for whitespace flags in xdl_hash_record() out of the loop > in xdl_prepare_ctx() and the rest comes from the change in hash > function. The first half of that alone is interesting enough ;-). > As I understand it the hash is implemented using SIMD > compiler intrinsics and the rust implementation is basically a > copy of the C code in libxxhash. I wonder how well xxhash performs > compared to our existing hash on platforms without an optimized > implementation. Yeah, that indeed is worth investigating. Thanks.