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[187.189.51.143]) by smtp.gmail.com with ESMTPSA id 586e51a60fabf-29de9bd87d9sm992701fac.50.2024.11.29.05.29.05 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 29 Nov 2024 05:29:06 -0800 (PST) Message-ID: <56210680-d6db-4618-92d3-60af0c999241@linaro.org> Date: Fri, 29 Nov 2024 07:29:03 -0600 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2] plugins: optimize cpu_index code generation To: Pierrick Bouvier , qemu-devel@nongnu.org Cc: =?UTF-8?Q?Alex_Benn=C3=A9e?= , Paolo Bonzini , Alexandre Iooss , Mahmoud Mandour References: <20241128213843.1023080-1-pierrick.bouvier@linaro.org> Content-Language: en-US From: Richard Henderson In-Reply-To: <20241128213843.1023080-1-pierrick.bouvier@linaro.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=2001:4860:4864:20::34; envelope-from=richard.henderson@linaro.org; helo=mail-oa1-x34.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 11/28/24 15:38, Pierrick Bouvier wrote: > When running with a single vcpu, we can return a constant instead of a > load when accessing cpu_index. > A side effect is that all tcg operations using it are optimized, most > notably scoreboard access. > When running a simple loop in user-mode, the speedup is around 20%. > > Signed-off-by: Pierrick Bouvier > > --- > > v2: > - no need to do a flush, as user-mode already does it when spawning a > second cpu (to honor CF_PARALLEL flags). > - change condition detection to use CF_PARALLEL instead > --- > accel/tcg/plugin-gen.c | 9 +++++++++ > 1 file changed, 9 insertions(+) Reviewed-by: Richard Henderson r~