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[80.187.81.137]) by smtp.gmail.com with ESMTPSA id m12-20020ae9e70c000000b007339c5114a9sm4334859qka.103.2023.08.01.11.22.00 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 01 Aug 2023 11:22:02 -0700 (PDT) Message-ID: <6c4e3b3a-8767-8591-f40e-84cbcf0cccde@redhat.com> Date: Tue, 1 Aug 2023 20:21:59 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.12.0 Subject: Re: [PATCH 0/8] gitlab: speed up msys windows jobs with GCC Content-Language: en-US To: =?UTF-8?Q?Daniel_P=2e_Berrang=c3=a9?= , Markus Armbruster Cc: qemu-devel@nongnu.org, =?UTF-8?Q?Philippe_Mathieu-Daud=c3=a9?= , Beraldo Leal , =?UTF-8?Q?Alex_Benn=c3=a9e?= , Wainer dos Santos Moschetta , Yonggang Luo , Paolo Bonzini References: <20230801130403.164060-1-berrange@redhat.com> <87bkfqyilp.fsf@pond.sub.org> From: Thomas Huth In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=170.10.133.124; envelope-from=thuth@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -21 X-Spam_score: -2.2 X-Spam_bar: -- X-Spam_report: (-2.2 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, NICE_REPLY_A=-0.092, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 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 01/08/2023 16.35, Daniel P. Berrangé wrote: > On Tue, Aug 01, 2023 at 03:53:22PM +0200, Markus Armbruster wrote: >> Daniel P. Berrangé writes: >> >>> This is an alternative and/or complementary to Thomas' proposal >>> to use CLang with msys: >>> >>> https://lists.gnu.org/archive/html/qemu-devel/2023-07/msg05402.html >>> >>> First of all, the current msys installer we're using is over 12 >>> months out of date. Thus after running the install, pacman then >>> replaces most of what we've just installed with new downloaded >>> content. Using the most update installer cuts 3+1/2 minutes off >>> the msys install time - 7 minutes becomes 3+1/2. >>> >>> Secondly, QEMU defaults to compiling with -O2 and this is more >>> computationally expensive for GCC. Switching to -O0 drops the >>> build time from 60 minutes down to 45 minutes. >> >> From the fine manual[*]: "The effectiveness of some warnings depends on >> optimizations also being enabled. For example '-Wsuggest-final-types' >> is more effective with link-time optimization and some instances of >> other warnings may not be issued at all unless optimization is enabled. >> While optimization in general improves the efficacy of control and data >> flow sensitive warnings, in some cases it may also cause false >> positives." Do we care? > > In general, yes, we do care. > > In this specific case though, we're battling to figure out the lesser > of multiple evils. I agree. Additionally, we also test compiling for Windows with the MinGW cross compiler suite in a Fedora container, and we still use the default optimization there, so we should have that covered. Thomas