From nobody Tue Jun 23 23:24:06 2026 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 07993C433F5 for ; Wed, 16 Mar 2022 07:11:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S243601AbiCPHMM (ORCPT ); Wed, 16 Mar 2022 03:12:12 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43882 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232916AbiCPHMH (ORCPT ); Wed, 16 Mar 2022 03:12:07 -0400 Received: from mail-yb1-xb4a.google.com (mail-yb1-xb4a.google.com [IPv6:2607:f8b0:4864:20::b4a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 227FB5DA6D for ; Wed, 16 Mar 2022 00:10:54 -0700 (PDT) Received: by mail-yb1-xb4a.google.com with SMTP id a3-20020a5b0ac3000000b006288f395b25so1329353ybr.18 for ; Wed, 16 Mar 2022 00:10:54 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=date:message-id:mime-version:subject:from:to:cc; bh=a+qisDvWjVObOyGt+FASRiXuVdhtv3LpxhYBq5xs2As=; b=QkjbnL9ondZiR68ZhRsbkiTB16VZ6RTH3D9ULnuAZHudsRB8UtWAYdIrDcj8ix3GwG 3Ba6gKWWu9o0Zv6FjtgELRiusoTwnEHPJu/9DCZc5RiA9XXFGcj8cfemzaWkSdS2wGGE 1/sB32qQSVadBMt1YW5FSogGW8MhOhnhjxD528RDM1GzhEL9a93uv7fBVxnTGt2B4FSR Ky1iWRNcsq+LcrC48nL7k3dImo0Uj8BFJzQSrQcniEs6wlZ2cENAH6dZXsLYIgB4Qun/ jRLQ2bGKEXkEqUsNE/Jb6s439JYz8hRrXwnKaPsemJJXeuMxgLyuk3DMvh21qc+nY7XA e/RQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:message-id:mime-version:subject:from:to:cc; bh=a+qisDvWjVObOyGt+FASRiXuVdhtv3LpxhYBq5xs2As=; b=B3wo8LpzeQc62DGl0UJ22LLX2tkJFKKO8rbhRweDXsEC1UIwQ5wm1luX/na164T2uz IT1cleBpUetkMbrnjTZLCY5aKNy4aUtvhqRx+ejMzdUxb9V9RQn0m57mBQ14qYWjnZkW DqV/p/jfh4gqx95Hl8KLBuu3khnUS7yn1Cha2fycOrcfdBbn6cIoa3ADXLn+opRCu8sS ZEe7mzfbUmcqvl+fZg1NwzhA4lfco9lw8r3bExZAJue943Ohpf5OGb92wjT8qjKyyQ8l 7G8Hyjbagbm0eWByiFaaAm2ld4lf037nFj4x4NbeqhbJZ0flHMZWGSauZYplITrYO71q +OrA== X-Gm-Message-State: AOAM532n/fnhQIHWLT8j48AfKqLiz6rZnWOY9iATZNNyBPLGloYJ2wFE 7tdbLd3j0ej8XGVGXg5GRCa6gGh1Evrj X-Google-Smtp-Source: ABdhPJzoXUwu/pi5bt8zVP3+SSR44xucIUvgs0SqbyAlgve09w3M3cY3SwYBmFocUwvvDwRJTaNIgAaMhftF X-Received: from irogers.svl.corp.google.com ([2620:15c:2cd:202:b17b:a969:45e3:7c15]) (user=irogers job=sendgmr) by 2002:a0d:f3c3:0:b0:2db:ed4b:8e2a with SMTP id c186-20020a0df3c3000000b002dbed4b8e2amr28469210ywf.397.1647414653304; Wed, 16 Mar 2022 00:10:53 -0700 (PDT) Date: Wed, 16 Mar 2022 00:10:49 -0700 Message-Id: <20220316071049.2368250-1-irogers@google.com> Mime-Version: 1.0 X-Mailer: git-send-email 2.35.1.723.g4982287a31-goog Subject: [PATCH] perf evlist: Avoid iteration for empty evlist. From: Ian Rogers To: Namhyung Kim , Jiri Olsa , Adrian Hunter , Linux Kernel Mailing List Cc: Ian Rogers Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" As seen with 'perf stat --null ..' and reported in: https://lore.kernel.org/lkml/YjCLcpcX2peeQVCH@kernel.org/ Fixes: 472832d2c000 ("perf evlist: Refactor evlist__for_each_cpu()") Signed-off-by: Ian Rogers --- tools/perf/util/evlist.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c index 8134d45e2164..a2dba9e00765 100644 --- a/tools/perf/util/evlist.c +++ b/tools/perf/util/evlist.c @@ -354,7 +354,10 @@ struct evlist_cpu_iterator evlist__cpu_begin(struct ev= list *evlist, struct affin .affinity =3D affinity, }; =20 - if (itr.affinity) { + if (evlist__empty(evlist)) { + /* Ensure the empty list doesn't iterate. */ + itr.evlist_cpu_map_idx =3D itr.evlist_cpu_map_nr; + } else if (itr.affinity) { itr.cpu =3D perf_cpu_map__cpu(evlist->core.all_cpus, 0); affinity__set(itr.affinity, itr.cpu.cpu); itr.cpu_map_idx =3D perf_cpu_map__idx(itr.evsel->core.cpus, itr.cpu); --=20 2.35.1.723.g4982287a31-goog