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[174.21.81.121]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-20710f4c9b9sm51362855ad.302.2024.09.10.11.18.04 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 10 Sep 2024 11:18:05 -0700 (PDT) Message-ID: <41ab786e-87b7-4aa9-a259-cdf5d14003a6@linaro.org> Date: Tue, 10 Sep 2024 11:18:03 -0700 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC 2/2] target/riscv: rvv: improve performance of RISC-V vector loads and stores on large amounts of data. To: Paolo Savini , qemu-devel@nongnu.org, qemu-riscv@nongnu.org Cc: Palmer Dabbelt , Alistair Francis , Bin Meng , Weiwei Li , Daniel Henrique Barboza , Liu Zhiwei , Helene Chelin , Max Chou References: <20240717153040.11073-1-paolo.savini@embecosm.com> <20240717153040.11073-3-paolo.savini@embecosm.com> <8e0c2afd-4c31-47f8-ade9-60a83ca20859@linaro.org> <1753bd69-6f7a-4b34-a7ae-8a0b225b72c9@embecosm.com> Content-Language: en-US From: Richard Henderson In-Reply-To: <1753bd69-6f7a-4b34-a7ae-8a0b225b72c9@embecosm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=2607:f8b0:4864:20::62e; envelope-from=richard.henderson@linaro.org; helo=mail-pl1-x62e.google.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On 9/10/24 04:20, Paolo Savini wrote: > Thanks for the feedback Richard, I'm working on the endianness. Could you please give me > more details about the atomicity issues you are referring to? For instance a 32-bit atomic memory operation in the guest must be implemented with a >= 32-bit atomic memory operation in the host. The main thing to remember is that memcpy() has no atomicity guarantee. It could be implemented as a byte loop. Thus you may only use memcpy with guest byte vectors. r~