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Wed, 23 Apr 2025 03:37:55 -0700 (PDT) X-Google-Smtp-Source: AGHT+IGCW39oL+DTOq34k/J8w9aq68eyfD5vKWVHY8SgLjQZi5WLtsz5YNU1V68pZbV8+BR4U4+dxw== X-Received: by 2002:a5d:64c2:0:b0:39f:175b:a68d with SMTP id ffacd0b85a97d-39f175ba69fmr6143780f8f.11.1745404675397; Wed, 23 Apr 2025 03:37:55 -0700 (PDT) Received: from gmonaco-thinkpadt14gen3.rmtit.csb ([185.107.56.30]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-39efa433141sm18478248f8f.35.2025.04.23.03.37.54 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 23 Apr 2025 03:37:54 -0700 (PDT) Message-ID: <02f047788f369cd0387d2934fa99fe3e8e1913c2.camel@redhat.com> Subject: Re: [PATCH v4 19/22] rv: Add rtapp_pagefault monitor From: Gabriele Monaco To: Nam Cao , Steven Rostedt , linux-trace-kernel@vger.kernel.org, linux-kernel@vger.kernel.org Cc: john.ogness@linutronix.de Date: Wed, 23 Apr 2025 12:37:53 +0200 In-Reply-To: <2eff7190ba245eb157f95ae461fef54183d07665.1745390829.git.namcao@linutronix.de> References: <2eff7190ba245eb157f95ae461fef54183d07665.1745390829.git.namcao@linutronix.de> Autocrypt: addr=gmonaco@redhat.com; prefer-encrypt=mutual; keydata=mDMEZuK5YxYJKwYBBAHaRw8BAQdAmJ3dM9Sz6/Hodu33Qrf8QH2bNeNbOikqYtxWFLVm0 1a0JEdhYnJpZWxlIE1vbmFjbyA8Z21vbmFjb0ByZWRoYXQuY29tPoiZBBMWCgBBFiEEysoR+AuB3R Zwp6j270psSVh4TfIFAmbiuWMCGwMFCQWjmoAFCwkIBwICIgIGFQoJCAsCBBYCAwECHgcCF4AACgk Q70psSVh4TfJzZgD/TXjnqCyqaZH/Y2w+YVbvm93WX2eqBqiVZ6VEjTuGNs8A/iPrKbzdWC7AicnK xyhmqeUWOzFx5P43S1E1dhsrLWgP Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.56.1 (3.56.1-1.fc42) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 On Wed, 2025-04-23 at 08:50 +0200, Nam Cao wrote: > Userspace real-time applications may have design flaws that they > raise > page faults in real-time threads, and thus have unexpected latencies. >=20 > Add an linear temporal logic monitor to detect this scenario. >=20 > Signed-off-by: Nam Cao > --- > =C2=A0kernel/trace/rv/Kconfig=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2= =A0=C2=A0=C2=A0 |=C2=A0 1 + > =C2=A0kernel/trace/rv/Makefile=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2= =A0=C2=A0 |=C2=A0 1 + > =C2=A0kernel/trace/rv/monitors/pagefault/Kconfig=C2=A0=C2=A0=C2=A0 | 11 += ++ > =C2=A0.../trace/rv/monitors/pagefault/pagefault.c=C2=A0=C2=A0 | 82 > +++++++++++++++++++ > =C2=A0.../trace/rv/monitors/pagefault/pagefault.h=C2=A0=C2=A0 | 57 ++++++= +++++++ > =C2=A0.../rv/monitors/pagefault/pagefault_trace.h=C2=A0=C2=A0 | 14 ++++ > =C2=A0kernel/trace/rv/rv_trace.h=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2= =A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= |=C2=A0 1 + > =C2=A0tools/verification/models/rtapp/pagefault.ltl |=C2=A0 1 + > =C2=A08 files changed, 168 insertions(+) > =C2=A0create mode 100644 kernel/trace/rv/monitors/pagefault/Kconfig > =C2=A0create mode 100644 kernel/trace/rv/monitors/pagefault/pagefault.c > =C2=A0create mode 100644 kernel/trace/rv/monitors/pagefault/pagefault.h > =C2=A0create mode 100644 > kernel/trace/rv/monitors/pagefault/pagefault_trace.h > =C2=A0create mode 100644 tools/verification/models/rtapp/pagefault.ltl >=20 > diff --git a/kernel/trace/rv/Kconfig b/kernel/trace/rv/Kconfig > index 5c407d291661..6f86d8501e87 100644 > --- a/kernel/trace/rv/Kconfig > +++ b/kernel/trace/rv/Kconfig > @@ -42,6 +42,7 @@ source "kernel/trace/rv/monitors/scpd/Kconfig" > =C2=A0source "kernel/trace/rv/monitors/snep/Kconfig" > =C2=A0source "kernel/trace/rv/monitors/sncid/Kconfig" > =C2=A0source "kernel/trace/rv/monitors/rtapp/Kconfig" > +source "kernel/trace/rv/monitors/pagefault/Kconfig" > =C2=A0# Add new monitors here > =C2=A0 > =C2=A0config RV_REACTORS > diff --git a/kernel/trace/rv/Makefile b/kernel/trace/rv/Makefile > index 9b28c2419995..353ecf939d0e 100644 > --- a/kernel/trace/rv/Makefile > +++ b/kernel/trace/rv/Makefile > @@ -13,6 +13,7 @@ obj-$(CONFIG_RV_MON_SCPD) +=3D monitors/scpd/scpd.o > =C2=A0obj-$(CONFIG_RV_MON_SNEP) +=3D monitors/snep/snep.o > =C2=A0obj-$(CONFIG_RV_MON_SNCID) +=3D monitors/sncid/sncid.o > =C2=A0obj-$(CONFIG_RV_MON_RTAPP) +=3D monitors/rtapp/rtapp.o > +obj-$(CONFIG_RV_MON_PAGEFAULT) +=3D monitors/pagefault/pagefault.o > =C2=A0# Add new monitors here > =C2=A0obj-$(CONFIG_RV_REACTORS) +=3D rv_reactors.o > =C2=A0obj-$(CONFIG_RV_REACT_PRINTK) +=3D reactor_printk.o > diff --git a/kernel/trace/rv/monitors/pagefault/Kconfig > b/kernel/trace/rv/monitors/pagefault/Kconfig > new file mode 100644 > index 000000000000..b31dee208459 > --- /dev/null > +++ b/kernel/trace/rv/monitors/pagefault/Kconfig > @@ -0,0 +1,11 @@ > +# SPDX-License-Identifier: GPL-2.0-only > +# > +config RV_MON_PAGEFAULT > + depends on RV > + select RV_LTL_MONITOR > + depends on RV_MON_RTAPP > + default y > + select LTL_MON_EVENTS_ID > + bool "pagefault monitor" > + help > + =C2=A0 Monitor that real-time tasks do not raise page faults > diff --git a/kernel/trace/rv/monitors/pagefault/pagefault.c > b/kernel/trace/rv/monitors/pagefault/pagefault.c > new file mode 100644 > index 000000000000..ff7df49871b2 > --- /dev/null > +++ b/kernel/trace/rv/monitors/pagefault/pagefault.c > @@ -0,0 +1,82 @@ > +// SPDX-License-Identifier: GPL-2.0 > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > + > +#define MODULE_NAME "pagefault" > + > +#include > +#include > +#include > + > +#include "pagefault.h" > +#include > + > +static void ltl_atoms_fetch(struct task_struct *task, struct > ltl_monitor *mon) > +{ > + ltl_atom_set(mon, LTL_RT, rt_or_dl_task(task)); > +} Mmh, you probably already considered that, so ignore my comment in that cas= e. I just realised this function would tell you a PI boosted task is an RT tas= k, is that acceptable in your model? It's probably a configuration mistake on its own if an RT task following th= ose rules shares resources with non-RT tasks not following them, but if that's something allowed, you may see this atom change more often than you'd like,= not sure if that can be something worth noting. Perhaps you could add a comment saying that this is not a problem and why (= e.g. instead of using rt_or_dl_task_policy for the job). What do you think? Besides this detail, the monitor looks good to me Reviewed-by: Gabriele Monaco Thanks, Gabriele