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[85.214.156.166]) by gmr-mx.google.com with ESMTPS id s12-20020a63770c000000b00412b1d698d9si55883pgc.0.2022.07.14.06.41.09 for (version=TLS1_2 cipher=ECDHE-ECDSA-CHACHA20-POLY1305 bits=256/256); Thu, 14 Jul 2022 06:41:09 -0700 (PDT) Received-SPF: pass (google.com: domain of ubely@ilbers.de designates 85.214.156.166 as permitted sender) client-ip=85.214.156.166; Authentication-Results: gmr-mx.google.com; spf=pass (google.com: domain of ubely@ilbers.de designates 85.214.156.166 as permitted sender) smtp.mailfrom=ubely@ilbers.de Received: from home.localnet (44-208-124-178-static.mgts.by [178.124.208.44] (may be forged)) (authenticated bits=0) by shymkent.ilbers.de (8.15.2/8.15.2/Debian-8+deb9u1) with ESMTPSA id 26EDf6it023450 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Thu, 14 Jul 2022 15:41:07 +0200 From: Uladzimir Bely To: isar-users Cc: Jan Kiszka Subject: Re: next: ccache broken for cross-compiling Date: Thu, 14 Jul 2022 16:41:05 +0300 Message-ID: <6773152.jJDZkT8p0M@home> In-Reply-To: <8e8e3b67-ab0d-8661-8611-adf5cfa2b06c@siemens.com> References: <8e8e3b67-ab0d-8661-8611-adf5cfa2b06c@siemens.com> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" X-Spam-Status: No, score=-1.0 required=5.0 tests=ALL_TRUSTED autolearn=unavailable autolearn_force=no version=3.4.2 X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on shymkent.ilbers.de X-TUID: Uv3acGVlbO4I In the email from Sunday, 10 July 2022 23:51:14 +03 user Jan Kiszka wrote: > Hi all, > > I've noticed that ccache is not doing its job with current next when > cross-building, e.g. mc:qemuarm64-bullseye:linux-mainline. It does work > as expected for native builds (mc:qemuamd64-bullseye:linux-mainline), > and it works fine with v0.9. Seems like an sbuild regression. > > Jan I did some checks on my side and it seems that it is not related to cross- build, but mostlry related to something specific to sbuild and kernel. Just some statistics (taken from 'ccache -s' output) 1. 'hello' cross-build for 'arm64' on 'next' branch (with sbuild) First run: Hits: 415 / 7479 (5.55 %) Second run: Hits: 7353 / 14958 (49.16 %) Everything OK, most of requests are hits ((7353 - 415) / 7479 = 92.7%) 2. 'linux-mainline' cross build for 'arm64' on 'next' branch (with sbuild) First run: Hits: 262 / 6208 (4.22 %) Second run: Hits: 644 / 12416 (5.19 %) Cache usage is relatively low ((644 - 262) / 6208 = 5.3%) compared to 'hello' 3. 'linux-mainline' native build for 'arm64' on 'next' branch (with sbuild) First run: Hits: 262 / 6208 (4.22 %) Second run: Hits: 644 / 12416 (5.19 %) The result is the same as for cross-build ((644 - 262) / 6208 = 5.3%), so the low cache usage problem is not related to cross or native build type. 4. 'linux-mainline' native build for 'arm64' on 'master' branch (without sbuild) First run: Hits: 262 / 6208 (4.22 %) Second run: Hits: 6469 / 12416 (52.10 %) Here, ccache usage is high ((6469 - 262) / 6208 = 99.98%) Most probably, Henning's assumption regarding inclusion of debug information (with different absolute paths in case of sbuild) making binaries in cache 'incompatible' is true. -- Uladzimir Bely