From nobody Mon Apr 6 23:07:00 2026 Received: from mail-dy1-f201.google.com (mail-dy1-f201.google.com [74.125.82.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 6CD3537E2F7 for ; Tue, 17 Mar 2026 17:57:19 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=74.125.82.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773770241; cv=none; b=UwXHGMSeZf73hQQEKQoTt6B/KRH6LPmLGV0+EeoDtVdc7A49oINOSDUe1qPda6F4dlkQgB9SHY6nXqjdjHVLVJQZBwy2BHfqVYj3hW0YyYmOyp6PoJxCarfGDvLA9p7f18A5CBxMCVkARGBYmNkgKtgrSjqubQkAGbpf9UNr4YM= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773770241; c=relaxed/simple; bh=wVIk574MaJ1ryn6M1d5QWZAOYLPanqIo/c++6wESi+o=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=RGbyr00ZyELZm4MMRmvYMc7xaSeoTzGmGuN0sYs3w3Iqk8Uus7+eKdDZFP5WF4QjI2RjSlSedlRK9dNzhWPoOO+RxmFlpf1fdIdVUAKQAPjKNpO+bJE9QxFuewBOjl0y7bQX1pJyzZJ25t/A2BOiJuewDfrNGT54eUI9ZbLbzH8= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--irogers.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=oQ09o728; arc=none smtp.client-ip=74.125.82.201 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--irogers.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="oQ09o728" Received: by mail-dy1-f201.google.com with SMTP id 5a478bee46e88-2bea61591fdso104918994eec.0 for ; Tue, 17 Mar 2026 10:57:19 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1773770238; x=1774375038; darn=vger.kernel.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=BC7DFlkd9xaG2royXDyXDCwOCftcIJRM1qoiGuRC8ho=; b=oQ09o728Vx81HGsHiHK0d37s3KPTWB2Cl61nLKZT9WT40UxI8S0RzI8zjXMd2G3og3 AfWe/lThC9i14oki8dXwoeGhjl9VSVcvnW+GUD1F6BurtjSuMg+/+hDrSnAbVL1Zjgrw IXlj8vHa5CVSJqHlxv7NiG71FiebqED+x5ytlPJuwdSDkNUAWb6O9FTIgvHYV0uAs0Ak CKDyKOZz/hXOrXsBd+SVOI/eQvRY5T5akDycZIVpDemNMWxrDfhg/9TKvrYZHEDFMGVV 0Ho5kB2nPHjYRScJUWWog3rSkJvB9qRW8/DP639FHAR023+4r9KiRGZrZTxEzgOAsC8I DPqg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1773770238; x=1774375038; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=BC7DFlkd9xaG2royXDyXDCwOCftcIJRM1qoiGuRC8ho=; b=ALx2hRnUgF8OnG/buh0vtq19oRAutW2XJwuw6KZQHtflKGMjGqXP+zBgP0d3zHrxk3 cZGfGnJJd0gNYwCxNstRKcGimZ0LmSv8e8sKL6XX/57rbJPZi99p5lt5Y01w/QHfDFOl HRs9kKD5EYpeSy3+ls3StCOP9ejoBdvmSCbYBLYRb3q4eD4lWH6GFMOFCoXCpdCqxMhH lTniCoSJhVPTp4qdRYvJPqcgYxEKhAVSVok6rbHr38edmb7i1nZAf3sXckql6zw/B3qD yJqQf7hYy7wYyOg/0Bz/47uNicEnNOkqe1Vm/P8TzuJEk362RszedLdCvnTY/0ggOddZ rMDA== X-Forwarded-Encrypted: i=1; AJvYcCVKGciy89TE4aIaJB80vfDwAUxxWUZ+nYLBkiYtUFupsH4KYfAdfzF0e8CGWJ9imAmIQdO6YSFOBJ8tO1g=@vger.kernel.org X-Gm-Message-State: AOJu0YwF25X9+C9T+ndb7imoM0u73mjRcW+US285F0u7YBdtujJB3a1Z KSiCz0zEr8QbdVNk/kBLGZarihPd9zLm95G8dE74MG89CdWPUUmoyYaItIcY+d67yOyQuGu/Ovb rHFh7h/Xrcg== X-Received: from dycmh3.prod.google.com ([2002:a05:693c:2583:b0:2be:2e48:5d13]) (user=irogers job=prod-delivery.src-stubby-dispatcher) by 2002:a05:7301:6790:b0:2c0:ad52:e657 with SMTP id 5a478bee46e88-2c0e50cb1bcmr159118eec.21.1773770208351; Tue, 17 Mar 2026 10:56:48 -0700 (PDT) Date: Tue, 17 Mar 2026 10:56:38 -0700 In-Reply-To: <20260317175642.161647-1-irogers@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260317175642.161647-1-irogers@google.com> X-Mailer: git-send-email 2.53.0.851.ga537e3e6e9-goog Message-ID: <20260317175642.161647-2-irogers@google.com> Subject: [PATCH v6 1/5] perf evsel: Improve falling back from cycles From: Ian Rogers To: tmricht@linux.ibm.com Cc: irogers@google.com, acme@kernel.org, agordeev@linux.ibm.com, gor@linux.ibm.com, hca@linux.ibm.com, japo@linux.ibm.com, linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org, linux-s390@vger.kernel.org, namhyung@kernel.org, sumanthk@linux.ibm.com Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Switch to using evsel__match rather than comparing perf_event_attr values, this is robust on hybrid architectures. Ensure evsel->pmu matches the evsel->core.attr. Remove exclude bits that get set in other fallback attempts when switching the event. Log the event name with modifiers when switching the event on fallback. Signed-off-by: Ian Rogers --- tools/perf/util/evsel.c | 45 ++++++++++++++++++++++++++++------------- tools/perf/util/evsel.h | 2 ++ 2 files changed, 33 insertions(+), 14 deletions(-) diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c index f59228c1a39e..bd14d9bbc91f 100644 --- a/tools/perf/util/evsel.c +++ b/tools/perf/util/evsel.c @@ -3785,25 +3785,42 @@ bool evsel__fallback(struct evsel *evsel, struct ta= rget *target, int err, { int paranoid; =20 - if ((err =3D=3D ENOENT || err =3D=3D ENXIO || err =3D=3D ENODEV) && - evsel->core.attr.type =3D=3D PERF_TYPE_HARDWARE && - evsel->core.attr.config =3D=3D PERF_COUNT_HW_CPU_CYCLES) { + if ((err =3D=3D ENODEV || err =3D=3D ENOENT || err =3D=3D ENXIO) && + evsel__match(evsel, HARDWARE, HW_CPU_CYCLES)) { /* - * If it's cycles then fall back to hrtimer based cpu-clock sw - * counter, which is always available even if no PMU support. - * - * PPC returns ENXIO until 2.6.37 (behavior changed with commit - * b0a873e). + * If it's the legacy hardware cycles event fails then fall back + * to hrtimer based cpu-clock sw counter, which is always + * available even if no PMU support. PPC returned ENXIO rather + * than ENODEV or ENOENT until 2.6.37. */ - evsel->core.attr.type =3D PERF_TYPE_SOFTWARE; + evsel->pmu =3D perf_pmus__find_by_type(PERF_TYPE_SOFTWARE); + assert(evsel->pmu); /* software is a "well-known" and can't fail PMU typ= e. */ + + /* Configure the event. */ + evsel->core.attr.type =3D PERF_TYPE_SOFTWARE; evsel->core.attr.config =3D target__has_cpu(target) ? PERF_COUNT_SW_CPU_CLOCK : PERF_COUNT_SW_TASK_CLOCK; - scnprintf(msg, msgsize, - "The cycles event is not supported, trying to fall back to %s", - target__has_cpu(target) ? "cpu-clock" : "task-clock"); + evsel->core.is_pmu_core =3D false; + + /* Remove excludes for new event. */ + if (evsel->fallenback_eacces) { + evsel->core.attr.exclude_kernel =3D 0; + evsel->core.attr.exclude_hv =3D 0; + evsel->fallenback_eacces =3D false; + } + if (evsel->fallenback_eopnotsupp) { + evsel->core.attr.exclude_guest =3D 0; + evsel->fallenback_eopnotsupp =3D false; + } =20 + /* Name is recomputed by evsel__name. */ zfree(&evsel->name); + + /* Log message. */ + scnprintf(msg, msgsize, + "The cycles event is not supported, trying to fall back to %s", + evsel__name(evsel)); return true; } else if (err =3D=3D EACCES && !evsel->core.attr.exclude_kernel && (paranoid =3D perf_event_paranoid()) > 1) { @@ -3830,7 +3847,7 @@ bool evsel__fallback(struct evsel *evsel, struct targ= et *target, int err, " samples", paranoid); evsel->core.attr.exclude_kernel =3D 1; evsel->core.attr.exclude_hv =3D 1; - + evsel->fallenback_eacces =3D true; return true; } else if (err =3D=3D EOPNOTSUPP && !evsel->core.attr.exclude_guest && !evsel->exclude_GH) { @@ -3851,7 +3868,7 @@ bool evsel__fallback(struct evsel *evsel, struct targ= et *target, int err, /* Apple M1 requires exclude_guest */ scnprintf(msg, msgsize, "Trying to fall back to excluding guest samples"= ); evsel->core.attr.exclude_guest =3D 1; - + evsel->fallenback_eopnotsupp =3D true; return true; } no_fallback: diff --git a/tools/perf/util/evsel.h b/tools/perf/util/evsel.h index a3d754c029a0..97f57fab28ce 100644 --- a/tools/perf/util/evsel.h +++ b/tools/perf/util/evsel.h @@ -124,6 +124,8 @@ struct evsel { bool default_metricgroup; /* A member of the Default metricgroup */ bool default_show_events; /* If a default group member, show the event = */ bool needs_uniquify; + bool fallenback_eacces; + bool fallenback_eopnotsupp; struct hashmap *per_pkg_mask; int err; int script_output_type; --=20 2.53.0.851.ga537e3e6e9-goog