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([2620:10d:c090:180::be7a]) by smtp.gmail.com with ESMTPSA id b26sm11209631pfo.158.2019.11.15.15.10.43 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 15 Nov 2019 15:10:44 -0800 (PST) To: Masahiro Yamada Cc: "linux-kernel@vger.kernel.org" From: Jens Axboe Subject: Recent slowdown in single object builds Message-ID: Date: Fri, 15 Nov 2019 16:10:42 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.9.0 MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, I've noticed that current -git is a lot slower at doing single object builds than earlier kernels. Here's an example, building the exact same file on 5.2 and -git: $ time make fs/io_uring.o real 0m5.953s user 0m5.402s sys 0m0.649s vs 5.2 based (with all the backports, identical file): $ time make fs/io_uring.o real 0m3.218s user 0m2.968s sys 0m0.520s Any idea what's going on here? It's almost twice as slow, which is problematic... -- Jens Axboe