From nobody Mon Feb 9 16:08:25 2026 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8F90D2DFF0D for ; Thu, 26 Jun 2025 12:36:18 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1750941380; cv=none; b=bgujWDvklvNwmYXri4P0zTMVIL4RPVQ+39hVP2EspG+o9WYPGFkpofvi1xKy/6R2phr7izUaHw+84NpoAZhv2HWiayoHS/yrI4TYj3S4J8vkuaRljLsCeUharCj2rl1TkgyWwSqm/kF8sluVUU/EZW0bUPMgiSeAdavHSFkONTs= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1750941380; c=relaxed/simple; bh=cOpwCH8DVaBtcRF0XPiHH/CxI5nZlNIp5nt3wZOKeWs=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=tc1GCIWopzUU+2gEtESe1d5wHCib/B9F/4ktZ2MfSzSiabu0bCxnr4BTzxV/6uPZ5J8s2Lptk/PUjvpEJnofucpl4VzBENvro36eQvcn8TaifeOvZfH43vmPpovgudNFWupwiK4JRCB0zgeosOa9V48kzb9RjCmJDmD5d4ceAkY= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=H9CPucYu; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="H9CPucYu" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1750941377; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=8wnuRWICz/3L1A5kr+hgYjZ7aQO+C6vPwfPXybDrYEg=; b=H9CPucYulMPrbxDTFima73+/Qs+YqmF7y8UVEAzh/p6AyU9mwPTnqPhEEqvnwJ/uwalqsN S8EFASm+5PqAz55BFOqZJd/ps7rzf55ClJYk0PODU/fOmKt0Mhyb0tEM+qWA28fN9mmCFP +0e6bXVtpvTC04c2YFcQtet3D+Gndpc= Received: from mx-prod-mc-02.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-106-pd2-vGxGP-6TCkJ4sGP65A-1; Thu, 26 Jun 2025 08:36:16 -0400 X-MC-Unique: pd2-vGxGP-6TCkJ4sGP65A-1 X-Mimecast-MFC-AGG-ID: pd2-vGxGP-6TCkJ4sGP65A_1750941375 Received: from mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.111]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-02.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 4B52B1955EC3; Thu, 26 Jun 2025 12:36:15 +0000 (UTC) Received: from fedora.brq.redhat.com (unknown [10.43.17.241]) by mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 683A9180045B; Thu, 26 Jun 2025 12:36:12 +0000 (UTC) From: Tomas Glozar To: Steven Rostedt Cc: linux-trace-kernel@vger.kernel.org, linux-kernel@vger.kernel.org, John Kacur , Luis Goncalves , Arnaldo Carvalho de Melo , Chang Yin , Costa Shulyupin , Crystal Wood , Gabriele Monaco , Tomas Glozar Subject: [PATCH v2 3/9] rtla/timerlat_bpf: Allow resuming tracing Date: Thu, 26 Jun 2025 14:33:59 +0200 Message-ID: <20250626123405.1496931-4-tglozar@redhat.com> In-Reply-To: <20250626123405.1496931-1-tglozar@redhat.com> References: <20250626123405.1496931-1-tglozar@redhat.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.111 Content-Type: text/plain; charset="utf-8" Currently, rtla-timerlat BPF program uses a global variable stored in a .bss section to store whether tracing has been stopped. Move the information to a separate map, so that it is easily writable from userspace, and add a function that clears the value, resuming tracing after it has been stopped. Signed-off-by: Tomas Glozar --- tools/tracing/rtla/src/timerlat.bpf.c | 13 +++++++++---- tools/tracing/rtla/src/timerlat_bpf.c | 13 +++++++++++++ tools/tracing/rtla/src/timerlat_bpf.h | 3 +++ 3 files changed, 25 insertions(+), 4 deletions(-) diff --git a/tools/tracing/rtla/src/timerlat.bpf.c b/tools/tracing/rtla/src= /timerlat.bpf.c index 96196d46e170..084cd10c21fc 100644 --- a/tools/tracing/rtla/src/timerlat.bpf.c +++ b/tools/tracing/rtla/src/timerlat.bpf.c @@ -28,6 +28,13 @@ struct { __type(value, unsigned long long); } summary_irq SEC(".maps"), summary_thread SEC(".maps"), summary_user SEC(= ".maps"); =20 +struct { + __uint(type, BPF_MAP_TYPE_ARRAY); + __uint(max_entries, 1); + __type(key, unsigned int); + __type(value, unsigned long long); +} stop_tracing SEC(".maps"); + struct { __uint(type, BPF_MAP_TYPE_RINGBUF); __uint(max_entries, 1); @@ -41,8 +48,6 @@ const volatile int irq_threshold; const volatile int thread_threshold; const volatile bool aa_only; =20 -int stop_tracing; - nosubprog unsigned long long map_get(void *map, unsigned int key) { @@ -109,7 +114,7 @@ nosubprog void set_stop_tracing(void) int value =3D 0; =20 /* Suppress further sample processing */ - stop_tracing =3D 1; + map_set(&stop_tracing, 0, 1); =20 /* Signal to userspace */ bpf_ringbuf_output(&signal_stop_tracing, &value, sizeof(value), 0); @@ -121,7 +126,7 @@ int handle_timerlat_sample(struct trace_event_raw_timer= lat_sample *tp_args) unsigned long long latency, latency_us; int bucket; =20 - if (stop_tracing) + if (map_get(&stop_tracing, 0)) return 0; =20 latency =3D tp_args->timer_latency / output_divisor; diff --git a/tools/tracing/rtla/src/timerlat_bpf.c b/tools/tracing/rtla/src= /timerlat_bpf.c index 0bc44ce5d69b..1666215dd687 100644 --- a/tools/tracing/rtla/src/timerlat_bpf.c +++ b/tools/tracing/rtla/src/timerlat_bpf.c @@ -106,6 +106,19 @@ int timerlat_bpf_wait(int timeout) return retval; } =20 +/* + * timerlat_bpf_restart_tracing - restart stopped tracing + */ +int timerlat_bpf_restart_tracing(void) +{ + unsigned int key =3D 0; + unsigned long long value =3D 0; + + return bpf_map__update_elem(bpf->maps.stop_tracing, + &key, sizeof(key), + &value, sizeof(value), BPF_ANY); +} + static int get_value(struct bpf_map *map_irq, struct bpf_map *map_thread, struct bpf_map *map_user, diff --git a/tools/tracing/rtla/src/timerlat_bpf.h b/tools/tracing/rtla/src= /timerlat_bpf.h index f1b54dbddb0e..118487436d30 100644 --- a/tools/tracing/rtla/src/timerlat_bpf.h +++ b/tools/tracing/rtla/src/timerlat_bpf.h @@ -18,6 +18,7 @@ int timerlat_bpf_attach(void); void timerlat_bpf_detach(void); void timerlat_bpf_destroy(void); int timerlat_bpf_wait(int timeout); +int timerlat_bpf_restart_tracing(void); int timerlat_bpf_get_hist_value(int key, long long *value_irq, long long *value_thread, @@ -28,6 +29,7 @@ int timerlat_bpf_get_summary_value(enum summary_field key, long long *value_thread, long long *value_user, int cpus); + static inline int have_libbpf_support(void) { return 1; } #else static inline int timerlat_bpf_init(struct timerlat_params *params) @@ -38,6 +40,7 @@ static inline int timerlat_bpf_attach(void) { return -1; } static inline void timerlat_bpf_detach(void) { }; static inline void timerlat_bpf_destroy(void) { }; static inline int timerlat_bpf_wait(int timeout) { return -1; } +static inline int timerlat_bpf_restart_tracing(void) { return -1; }; static inline int timerlat_bpf_get_hist_value(int key, long long *value_irq, long long *value_thread, --=20 2.49.0