From patchwork Wed Nov 29 06:02:11 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ian Rogers X-Patchwork-Id: 13472248 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 67291C4167B for ; Wed, 29 Nov 2023 06:04:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:To:From:Subject:References:Mime-Version :Message-Id:In-Reply-To:Date:Reply-To:Cc:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=NjC2ZY2gEEGOYamOLawUl3TE4bhZ78MUN4bmGPLpObU=; b=R0rr/l1VtZDFj3 LtJ7MJp/cmrDxQJ+KyiKZ4pLft0y9U57PL4VRCUQVGh7umiLVqFiIl4O5VjhFDMRYmB8DruaExDFH HNjg9WWy28WVOBm7431rCTdL148N098DNZ4HdeVShxuwaYlNWEeDvI0eOohWWFxGmHjX/0oK30wbM rD6d1vcx5RDKPN9qd6QlLec5NkzCEN0L450Iya588a3ue3NE7WlPKi1Kzjj5RB7hly4eWOqIbLviC NAec4sc92zWf3R5AjOhujZeWSaai7cbfoJiPAC6qYHG6+exlfjKCNHKNeQbGMZ+eTlfmfre1H6L+A g2OkE3bSkhCi4MTQpvpw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1r8Dfg-007A5A-2Q; Wed, 29 Nov 2023 06:03:40 +0000 Received: from mail-yw1-x114a.google.com ([2607:f8b0:4864:20::114a]) by bombadil.infradead.org with esmtps (Exim 4.96 #2 (Red Hat Linux)) id 1r8Der-0079Q6-2N for linux-arm-kernel@lists.infradead.org; Wed, 29 Nov 2023 06:02:51 +0000 Received: by mail-yw1-x114a.google.com with SMTP id 00721157ae682-5c5daf2baccso84753537b3.3 for ; Tue, 28 Nov 2023 22:02:48 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1701237768; x=1701842568; darn=lists.infradead.org; h=to:from:subject:references:mime-version:message-id:in-reply-to:date :from:to:cc:subject:date:message-id:reply-to; bh=gdtDmuZlpO8R+sCZuGq6XIuCqB6n5MWFW+Mek7m4zb4=; b=kSSvG/jQD/GjgBiAyintjqtLPWVaTGD77BkK9fDPiKw39y+/0wnquWL+eoP/lmgGZA zeHK6PZ0f9xVy5akjVUpX/ZebElMFtoN3rY+P6UNOjawO++8E28Sr+iJ8UBuZZOt688w CStcpVJLQGqMMUXqZm4r5Zye5n/BJlmk/gU7HZgxQYjar6Ia/p+llsiw56rVa7hejnR6 +P12269j0oqqezyLeUOBVixMseC6aYxM2ddkaagW12FizLlLrlEXuBVz0NKQ/mckB3rS Xzxtt5Wl36h9LGz6bN1g+9813im1huThj5koqzw0PxxwczFfD6olFHPO6L9wG5TY9vPp zYww== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1701237768; x=1701842568; h=to:from:subject:references:mime-version:message-id:in-reply-to:date :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=gdtDmuZlpO8R+sCZuGq6XIuCqB6n5MWFW+Mek7m4zb4=; b=s6bWtrzw3q3kPeCbihNegVUu3Pa5uut7Zv0Dlze3+Jpm7x5fSEtGMuU+KXA7voV48J UHkC/zO6KRZYB0JSNsAJcw/PHVyhD2RYtgJJ9gVrRKS/XjqkbD5dCdEiHdx/CdAzDYCv tboY5vNwEOARkE7Nw4RKVnH8dvFZVjmyughHtIaJHllGIkrXpPHfdMUpZI0kuu5qDTrq bYDMINEQfGgLhgl4tZwYvOyvQ0UClp4ohAvxFyw+w5nvdbElhI/m6ujQN4qPyN1ToJ9i 1Y7vmzjT+hjezmxLb0reV/z6qohwylifDEW5EyKiDKLNl/mYH4dKiTWd+HAhdD4sMVNJ EB9g== X-Gm-Message-State: AOJu0Yxb4b61tsv7vnP3sEdv44hDg1aDZn53qQxdzebsMJu0NqKdV/WZ oInAlEqevSAHlAssb4HIqiIte8rSRNaR X-Google-Smtp-Source: AGHT+IFWysPah8NVdJGuOS/cub7nCqzkPRr9kIA04P1LJGn4EJzUePlje+77t8xYTmBpNHAmkcV+MNHmEHhD X-Received: from irogers.svl.corp.google.com ([2620:15c:2a3:200:763b:80fa:23ca:96f8]) (user=irogers job=sendgmr) by 2002:a05:690c:fcd:b0:5ca:fef:82a4 with SMTP id dg13-20020a05690c0fcd00b005ca0fef82a4mr623872ywb.4.1701237768039; Tue, 28 Nov 2023 22:02:48 -0800 (PST) Date: Tue, 28 Nov 2023 22:02:11 -0800 In-Reply-To: <20231129060211.1890454-1-irogers@google.com> Message-Id: <20231129060211.1890454-15-irogers@google.com> Mime-Version: 1.0 References: <20231129060211.1890454-1-irogers@google.com> X-Mailer: git-send-email 2.43.0.rc1.413.gea7ed67945-goog Subject: [PATCH v1 14/14] libperf cpumap: Document perf_cpu_map__nr's behavior From: Ian Rogers To: Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Mark Rutland , Alexander Shishkin , Jiri Olsa , Namhyung Kim , Ian Rogers , Adrian Hunter , Suzuki K Poulose , Mike Leach , James Clark , Leo Yan , John Garry , Will Deacon , Thomas Gleixner , Darren Hart , Davidlohr Bueso , " =?utf-8?q?Andr=C3=A9_Almeida?= " , Kan Liang , K Prateek Nayak , Sean Christopherson , Paolo Bonzini , Kajol Jain , Athira Rajeev , Andrew Jones , Alexandre Ghiti , Atish Patra , "Steinar H. Gunderson" , Yang Jihong , Yang Li , Changbin Du , Sandipan Das , Ravi Bangoria , Paran Lee , Nick Desaulniers , Huacai Chen , Yanteng Si , linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org, coresight@lists.linaro.org, linux-arm-kernel@lists.infradead.org, bpf@vger.kernel.org X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20231128_220249_815235_F1721E35 X-CRM114-Status: GOOD ( 14.66 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org perf_cpu_map__nr's behavior around an empty CPU map is strange as it returns that there is 1 CPU. Changing code that may rely on this behavior is hard, we can at least document the behavior. Signed-off-by: Ian Rogers Reviewed-by: James Clark --- tools/lib/perf/include/perf/cpumap.h | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/tools/lib/perf/include/perf/cpumap.h b/tools/lib/perf/include/perf/cpumap.h index 523e4348fc96..90457d17fb2f 100644 --- a/tools/lib/perf/include/perf/cpumap.h +++ b/tools/lib/perf/include/perf/cpumap.h @@ -44,7 +44,18 @@ LIBPERF_API struct perf_cpu_map *perf_cpu_map__merge(struct perf_cpu_map *orig, LIBPERF_API struct perf_cpu_map *perf_cpu_map__intersect(struct perf_cpu_map *orig, struct perf_cpu_map *other); LIBPERF_API void perf_cpu_map__put(struct perf_cpu_map *map); +/** + * perf_cpu_map__cpu - get the CPU value at the given index. Returns -1 if index + * is invalid. + */ LIBPERF_API struct perf_cpu perf_cpu_map__cpu(const struct perf_cpu_map *cpus, int idx); +/** + * perf_cpu_map__nr - for an empty map returns 1, as perf_cpu_map__cpu returns a + * cpu of -1 for an invalid index, this makes an empty map + * look like it contains the "any CPU"/dummy value. Otherwise + * the result is the number CPUs in the map plus one if the + * "any CPU"/dummy value is present. + */ LIBPERF_API int perf_cpu_map__nr(const struct perf_cpu_map *cpus); /** * perf_cpu_map__has_any_cpu_or_is_empty - is map either empty or has the "any CPU"/dummy value.