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([2a02:6b6a:b566:0:39c7:f90d:557:dc30]) by smtp.gmail.com with ESMTPSA id fc13-20020a05600c524d00b003db01178b62sm17739492wmb.40.2023.02.06.04.18.00 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 06 Feb 2023 04:18:01 -0800 (PST) Message-ID: Date: Mon, 6 Feb 2023 12:18:00 +0000 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.4.2 Subject: Re: [External] Re: [PATCH v6 00/11] Parallel CPU bringup for x86_64 Content-Language: en-US To: David Woodhouse , Russ Anderson Cc: tglx@linutronix.de, arjan@linux.intel.com, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, hpa@zytor.com, x86@kernel.org, pbonzini@redhat.com, paulmck@kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, rcu@vger.kernel.org, mimoja@mimoja.de, hewenliang4@huawei.com, thomas.lendacky@amd.com, seanjc@google.com, pmenzel@molgen.mpg.de, fam.zheng@bytedance.com, punit.agrawal@bytedance.com, simon.evans@bytedance.com, liangma@liangbit.com References: <20230202215625.3248306-1-usama.arif@bytedance.com> <20230205191734.GA6027@hpe.com> <3b626936ccc4d5123cb9113378bec6f77182def3.camel@infradead.org> From: Usama Arif In-Reply-To: <3b626936ccc4d5123cb9113378bec6f77182def3.camel@infradead.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 06/02/2023 08:28, David Woodhouse wrote: > On Sun, 2023-02-05 at 13:17 -0600, Russ Anderson wrote: >> >> Gave the v6 patchset a try on a system with 1920 logocal cpus >> (sixteen 60 core Sapphire Rapids sockets with Hyperthreadding >> enabled). >> >> Without the patchset it took 71 seconds to start all the cpus. >> With the v6 patchset it took 14 seconds to start all the cpus, >> a reduction of 57 seconds.  That is impressive. >> >> Full boot, to root login prompt, without patches takes 223 seconds. >> This patchset reduces the full boot time by 57 seconds, a 25% >> reduction. > > Nice; thanks for testing. > > Is that with just the "part1" patch series which has been posted, or > also with the 'parallel part 2' still taking shape in the tree at > https://git.infradead.org/users/dwmw2/linux.git/shortlog/refs/heads/parallel-6.2-rc6 > > I believe Usama said the second phase of parallelism didn't really help > much in terms of overall timing? Confirming that *without* all the > debug prints would be interesting. And we can look for what still > *could* be made parallel. I think it would be interesting to get the numbers for such a big machine for 3 cases: part1, part1+reuse timer calibration and part1+part2. Russ mentioned testing v6, so I guess the above numbers are for part1+reuse timer calibration. For my machine the smpboot times were: No patches: 700ms part 1:100ms part1+reuse timer calibration: 30ms part1+part2: 30ms Thanks, Usama