From nobody Mon Apr 6 17:26:12 2026 Received: from mail-dl1-f74.google.com (mail-dl1-f74.google.com [74.125.82.74]) (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 0DAB33168FB for ; Wed, 18 Mar 2026 23:46:05 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=74.125.82.74 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773877567; cv=none; b=WOiqEJ2rp+CVLkmr5h+Svo0lwtojhsylePkopDvYMqBA/MOXH7UhrO2Qaae1G4Ng+U4KebiYoc7vriYP0ZGnkEXkht+OG76x1w1gFDO3kYTrZYr1WwI3pFOeb71UXVOkJaMG+3hT0A2m6hP6hyifpgxjoyMAGLvcUNhi3froRaM= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773877567; c=relaxed/simple; bh=U8LqxsgGl8pPzMoHQSm3GXUaosjRDy/a3rvRqghM3i4=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=JcI/12Y75DEJYmFaKCGs+0f8fhD4XefKyGbUiWbjgAA/hZ9VsE6kb0IccXk501VF6fNgH6EKXeWmY3HG2nL4RjmMa3rvbDMixkivIr5aPOlF91hcU0cSOkQVRPDLhYyVAilEoKF8T64fk0Sd1vii/pnsFcS6hrwqjG3+yGiL/+s= 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=YJJpnqBk; arc=none smtp.client-ip=74.125.82.74 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="YJJpnqBk" Received: by mail-dl1-f74.google.com with SMTP id a92af1059eb24-128d285d6c3so410710c88.1 for ; Wed, 18 Mar 2026 16:46:05 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1773877565; x=1774482365; 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=FHgnOqAqVJ/nZ21E+abJVIPEw9OV5mDZ+DHTpPzA2N8=; b=YJJpnqBkiT68ho/nAKjUhO1hO5eOO8U6zswV3CoyDTPuxhLx+HivLXX/LajsfnAsxy 9do3LJPLgQqmEpdLeqAcl8bORSDkbNTyYpmJSdRIUPVImQTAFo/CYdvWPmQoi2vsJcjw NqIvapejS5CLO/ByLAf227R/xLhjnEHLa3LDCTYqh9J9wKB9OCL9ogSkwIfYC1RfPWJK 7lZNt9vg7ltxNpEywW3fyC4KFIjfF6595g6YycP8IxZn91JqyEitJSvGmJY+SF0BT8fU mV+/hlW0ks3ySin7OZZ0Ewni9fu91kvBNP7L/vy3QILF6IPccn0valXkFhc3Bp1toUms Mydw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1773877565; x=1774482365; 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=FHgnOqAqVJ/nZ21E+abJVIPEw9OV5mDZ+DHTpPzA2N8=; b=EE8VIedaaAWzH/8hWFIbBM3hSqsb1nNLintkHV7u3tZfcxOKLIqZyVL7Ny51tLgN2/ v09YVlA9UkxrVk8F9hE5hMMurw0nENhfIJy6R1ed33TU6g0XtOFAegY6SB8M9nKHHa0v +qlCs9aaS9rGHJMBe0SASNYqmN+283sLlmrb0KpyB8Cjtfhz40QVZGSwSbyd+kUhamHs N/A42rayYEg89bMz7Gt/PWfU6VeiXuttLgE674e5k3slm3BQvyGuGSb1W/NM6YN6DhrB GQg2QLmvdAZ7hGpIqYCGebD+gP3L5yDSkZiHn7Yj+QaUexkjqp3qv0CwTauNeeJQxFDt sXWQ== X-Forwarded-Encrypted: i=1; AJvYcCWWuKbZBqJO+mvuNHNfuXJq6PW0lshpGtMTv8LDT5q9IWTCvwXDcm3Tvq12TOIhZgMxBUWh4S1w4NwC7tU=@vger.kernel.org X-Gm-Message-State: AOJu0YzCxnaDQmSlpZMZXLCPhEk6j5yTqHSkg581YVuwihMn5CVL+9FJ CLahMTyN6hXd7DIOABCdAh4i4hSHEC3wVlFxtWYDHbWIOkqIWpz1B+V0SnIHEp5CZD9iITtmfNE ye9DmYUDtkA== X-Received: from dlbvs5.prod.google.com ([2002:a05:7022:3f05:b0:128:cff2:6560]) (user=irogers job=prod-delivery.src-stubby-dispatcher) by 2002:a05:7022:250f:b0:128:ea68:27f4 with SMTP id a92af1059eb24-1299baa0042mr2372545c88.4.1773877564922; Wed, 18 Mar 2026 16:46:04 -0700 (PDT) Date: Wed, 18 Mar 2026 16:45:56 -0700 In-Reply-To: <20260318234600.730340-1-irogers@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260318175808.582009-1-irogers@google.com> <20260318234600.730340-1-irogers@google.com> X-Mailer: git-send-email 2.53.0.851.ga537e3e6e9-goog Message-ID: <20260318234600.730340-2-irogers@google.com> Subject: [PATCH v8 1/5] perf evsel: Improve falling back from cycles From: Ian Rogers To: acme@kernel.org, namhyung@kernel.org, tmricht@linux.ibm.com Cc: irogers@google.com, 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, 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 Tested-by: Thomas Richter --- 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