From: Mathieu Poirier <mathieu.poirier@linaro.org>
To: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Suzuki K Poulose <suzuki.poulose@arm.com>,
linux-arm-kernel@lists.infradead.org, coresight@lists.linaro.org,
mike.leach@linaro.org, lcherian@marvell.com,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH V3 08/14] coresight: core: Add support for dedicated percpu sinks
Date: Tue, 16 Feb 2021 13:44:19 -0700 [thread overview]
Message-ID: <20210216204419.GB2936551@xps15> (raw)
In-Reply-To: <72bd5139-a6e1-64c0-c111-818bc04a81b8@arm.com>
On Tue, Feb 16, 2021 at 04:10:18PM +0530, Anshuman Khandual wrote:
>
>
> On 2/5/21 12:04 AM, Mathieu Poirier wrote:
> > On Thu, Jan 28, 2021 at 09:16:34AM +0000, Suzuki K Poulose wrote:
> >> On 1/27/21 8:55 AM, Anshuman Khandual wrote:
> >>> Add support for dedicated sinks that are bound to individual CPUs. (e.g,
> >>> TRBE). To allow quicker access to the sink for a given CPU bound source,
> >>> keep a percpu array of the sink devices. Also, add support for building
> >>> a path to the CPU local sink from the ETM.
> >>>
> >>> This adds a new percpu sink type CORESIGHT_DEV_SUBTYPE_SINK_PERCPU_SYSMEM.
> >>> This new sink type is exclusively available and can only work with percpu
> >>> source type device CORESIGHT_DEV_SUBTYPE_SOURCE_PERCPU_PROC.
> >>>
> >>> This defines a percpu structure that accommodates a single coresight_device
> >>> which can be used to store an initialized instance from a sink driver. As
> >>> these sinks are exclusively linked and dependent on corresponding percpu
> >>> sources devices, they should also be the default sink device during a perf
> >>> session.
> >>>
> >>> Outwards device connections are scanned while establishing paths between a
> >>> source and a sink device. But such connections are not present for certain
> >>> percpu source and sink devices which are exclusively linked and dependent.
> >>> Build the path directly and skip connection scanning for such devices.
> >>>
> >>> Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
> >>> Cc: Mike Leach <mike.leach@linaro.org>
> >>> Cc: Suzuki K Poulose <suzuki.poulose@arm.com>
> >>> Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
> >>> ---
> >>> Changes in V3:
> >>>
> >>> - Updated coresight_find_default_sink()
> >>>
> >>> drivers/hwtracing/coresight/coresight-core.c | 16 ++++++++++++++--
> >>> include/linux/coresight.h | 12 ++++++++++++
> >>> 2 files changed, 26 insertions(+), 2 deletions(-)
> >>>
> >>> diff --git a/drivers/hwtracing/coresight/coresight-core.c b/drivers/hwtracing/coresight/coresight-core.c
> >>> index 0062c89..4795e28 100644
> >>> --- a/drivers/hwtracing/coresight/coresight-core.c
> >>> +++ b/drivers/hwtracing/coresight/coresight-core.c
> >>> @@ -23,6 +23,7 @@
> >>> #include "coresight-priv.h"
> >>> static DEFINE_MUTEX(coresight_mutex);
> >>> +DEFINE_PER_CPU(struct coresight_device *, csdev_sink);
> >>> /**
> >>> * struct coresight_node - elements of a path, from source to sink
> >>> @@ -784,6 +785,13 @@ static int _coresight_build_path(struct coresight_device *csdev,
> >>> if (csdev == sink)
> >>> goto out;
> >>> + if (coresight_is_percpu_source(csdev) && coresight_is_percpu_sink(sink) &&
> >>> + sink == per_cpu(csdev_sink, source_ops(csdev)->cpu_id(csdev))) {
> >>> + _coresight_build_path(sink, sink, path);
> >
> > The return value for _coresight_build_path() needs to be checked. Otherwise a
> > failure to allocate a node for the sink will go unoticed and make for a very
> > hard problem to debug.
>
> How about this instead ?
>
> diff --git a/drivers/hwtracing/coresight/coresight-core.c b/drivers/hwtracing/coresight/coresight-core.c
> index 4795e28..e93e669 100644
> --- a/drivers/hwtracing/coresight/coresight-core.c
> +++ b/drivers/hwtracing/coresight/coresight-core.c
> @@ -787,9 +787,10 @@ static int _coresight_build_path(struct coresight_device *csdev,
>
> if (coresight_is_percpu_source(csdev) && coresight_is_percpu_sink(sink) &&
> sink == per_cpu(csdev_sink, source_ops(csdev)->cpu_id(csdev))) {
> - _coresight_build_path(sink, sink, path);
> - found = true;
> - goto out;
> + if (_coresight_build_path(sink, sink, path) == 0) {
> + found = true;
> + goto out;
> + }
I am missing the context now but it is a step in the right direction. I will
re-assess on your next revision.
> }
>
> /* Not a sink - recursively explore each port found on this element */
>
> >
> >>> + found = true;
> >>> + goto out;
> >>> + }
> >>> +
> >>> /* Not a sink - recursively explore each port found on this element */
> >>> for (i = 0; i < csdev->pdata->nr_outport; i++) {
> >>> struct coresight_device *child_dev;
> >>> @@ -999,8 +1007,12 @@ coresight_find_default_sink(struct coresight_device *csdev)
> >>> int depth = 0;
> >>> /* look for a default sink if we have not found for this device */
> >>> - if (!csdev->def_sink)
> >>> - csdev->def_sink = coresight_find_sink(csdev, &depth);
> >>> + if (!csdev->def_sink) {
> >>> + if (coresight_is_percpu_source(csdev))
> >>> + csdev->def_sink = per_cpu(csdev_sink, source_ops(csdev)->cpu_id(csdev));
> >>> + if (!csdev->def_sink)
> >>> + csdev->def_sink = coresight_find_sink(csdev, &depth);
> >>> + }
> >>> return csdev->def_sink;
> >>> }
> >>> diff --git a/include/linux/coresight.h b/include/linux/coresight.h
> >>> index 976ec26..bc3a5ca 100644
> >>> --- a/include/linux/coresight.h
> >>> +++ b/include/linux/coresight.h
> >>> @@ -50,6 +50,7 @@ enum coresight_dev_subtype_sink {
> >>> CORESIGHT_DEV_SUBTYPE_SINK_PORT,
> >>> CORESIGHT_DEV_SUBTYPE_SINK_BUFFER,
> >>> CORESIGHT_DEV_SUBTYPE_SINK_SYSMEM,
> >>> + CORESIGHT_DEV_SUBTYPE_SINK_PERCPU_SYSMEM,
> >
> > Do we absolutely need to add a new sink type? It is only used in
> > _coresight_build_path() and that code could be:
> >
> > if (coresight_is_percpu_source(csdev)) {
> > sink == per_cpu(csdev_sink, source_ops(csdev)->cpu_id(csdev));
>
> Do you mean if (sink == per_cpu(...)) above ?
>
> > if (sink && sink == csdev) {
>
> How could the sink fetched from the source csdev be the same ?
The above should have been:
if (coresight_is_percpu_source(csdev)) {
per_cpu_sink == per_cpu(csdev_sink, source_ops(csdev)->cpu_id(csdev));
if (per_cpu_sink && per_cpu_sink == sink) {
Apologies for the confusion.
Mathieu
>
> I would still suggest keeping CORESIGHT_DEV_SUBTYPE_SINK_PERCPU_SYSMEM for
> logical separation between source and sink, which also improves clarity
> and readability.
next prev parent reply other threads:[~2021-02-16 20:45 UTC|newest]
Thread overview: 90+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-27 8:55 [PATCH V3 00/14] arm64: coresight: Enable ETE and TRBE Anshuman Khandual
2021-01-27 8:55 ` [PATCH V3 01/14] coresight: etm-perf: Allow an event to use different sinks Anshuman Khandual
2021-02-01 23:17 ` Mathieu Poirier
2021-02-02 9:42 ` Suzuki K Poulose
2021-02-02 16:33 ` Mike Leach
2021-02-02 22:41 ` Suzuki K Poulose
2021-02-04 12:27 ` Mike Leach
2021-02-02 16:37 ` Mathieu Poirier
2021-01-27 8:55 ` [PATCH V3 02/14] coresight: Do not scan for graph if none is present Anshuman Khandual
2021-02-01 23:44 ` Mathieu Poirier
2021-02-02 11:10 ` Mike Leach
2021-02-02 14:36 ` Suzuki K Poulose
2021-01-27 8:55 ` [PATCH V3 03/14] coresight: etm4x: Add support for PE OS lock Anshuman Khandual
2021-02-02 17:40 ` Mathieu Poirier
2021-02-02 18:03 ` Mathieu Poirier
2021-02-15 14:08 ` Mike Leach
2021-01-27 8:55 ` [PATCH V3 04/14] coresight: ete: Add support for ETE sysreg access Anshuman Khandual
2021-02-02 17:52 ` Mathieu Poirier
2021-02-03 15:51 ` Suzuki K Poulose
2021-02-15 14:08 ` Mike Leach
2021-01-27 8:55 ` [PATCH V3 05/14] coresight: ete: Add support for ETE tracing Anshuman Khandual
2021-02-02 18:56 ` Mathieu Poirier
2021-02-02 22:50 ` Suzuki K Poulose
2021-02-15 13:21 ` Mike Leach
2021-02-15 14:08 ` Mike Leach
2021-01-27 8:55 ` [PATCH V3 06/14] dts: bindings: Document device tree bindings for ETE Anshuman Khandual
2021-02-09 19:00 ` Rob Herring
2021-02-10 12:33 ` Suzuki K Poulose
2021-02-18 18:33 ` Rob Herring
2021-02-18 22:51 ` Suzuki K Poulose
2021-01-27 8:55 ` [PATCH V3 07/14] coresight: etm-perf: Handle stale output handles Anshuman Khandual
2021-02-03 19:05 ` Mathieu Poirier
2021-02-03 23:36 ` Suzuki K Poulose
2021-02-15 16:27 ` Mike Leach
2021-01-27 8:55 ` [PATCH V3 08/14] coresight: core: Add support for dedicated percpu sinks Anshuman Khandual
2021-01-28 9:16 ` Suzuki K Poulose
2021-02-04 18:34 ` Mathieu Poirier
2021-02-16 10:40 ` Anshuman Khandual
2021-02-16 20:44 ` Mathieu Poirier [this message]
2021-02-16 10:21 ` Anshuman Khandual
2021-02-15 16:27 ` Mike Leach
2021-02-15 16:56 ` Mathieu Poirier
2021-02-15 17:58 ` Mike Leach
2021-02-16 20:30 ` Mathieu Poirier
2021-01-27 8:55 ` [PATCH V3 09/14] arm64: Add TRBE definitions Anshuman Khandual
2021-01-28 9:31 ` Suzuki K Poulose
2021-01-28 17:18 ` Catalin Marinas
2021-02-15 18:06 ` Mike Leach
2021-01-27 8:55 ` [PATCH V3 10/14] arm64: nvhe: Allow TRBE access at EL1 Anshuman Khandual
2021-01-27 9:58 ` Marc Zyngier
2021-01-28 9:34 ` Suzuki K Poulose
2021-01-28 9:46 ` Marc Zyngier
2021-01-28 9:48 ` Suzuki K Poulose
2021-01-27 8:55 ` [PATCH V3 11/14] coresight: sink: Add TRBE driver Anshuman Khandual
[not found] ` <12cdc8ca-0a69-bfba-bbcd-fb392d6ca051@arm.com>
2021-02-02 5:55 ` Anshuman Khandual
2021-02-05 17:53 ` Mathieu Poirier
2021-02-08 4:20 ` Anshuman Khandual
2021-02-09 17:39 ` Mathieu Poirier
2021-02-10 4:12 ` Anshuman Khandual
2021-02-10 16:54 ` Mathieu Poirier
2021-02-10 19:00 ` Mathieu Poirier
2021-02-12 5:43 ` Anshuman Khandual
2021-02-12 17:02 ` Mathieu Poirier
2021-02-11 19:00 ` Mathieu Poirier
2021-02-12 3:31 ` Anshuman Khandual
2021-02-12 16:57 ` Mathieu Poirier
2021-02-15 9:26 ` Anshuman Khandual
2021-02-12 20:26 ` Mathieu Poirier
2021-02-15 9:46 ` Anshuman Khandual
2021-02-16 9:00 ` Mike Leach
2021-02-16 9:44 ` Anshuman Khandual
2021-02-16 12:12 ` Mike Leach
2021-02-18 7:50 ` Suzuki K Poulose
2021-02-18 14:30 ` Mike Leach
2021-02-18 15:14 ` Suzuki K Poulose
2021-02-22 10:42 ` Mike Leach
2021-01-27 8:55 ` [PATCH V3 12/14] dts: bindings: Document device tree bindings for Arm TRBE Anshuman Khandual
2021-02-09 19:04 ` Rob Herring
2021-01-27 8:55 ` [PATCH V3 13/14] perf: aux: Add flags for the buffer format Anshuman Khandual
2021-01-27 12:51 ` Peter Zijlstra
2021-02-16 10:59 ` Mike Leach
2021-01-27 8:55 ` [PATCH V3 14/14] coresight: etm-perf: Add support for trace " Anshuman Khandual
2021-01-27 12:54 ` Peter Zijlstra
2021-01-27 13:00 ` Al Grant
2021-02-18 3:05 ` Anshuman Khandual
2021-01-27 14:12 ` Suzuki K Poulose
2021-02-16 11:01 ` Mike Leach
2021-01-27 18:50 ` [PATCH V3 00/14] arm64: coresight: Enable ETE and TRBE Mathieu Poirier
2021-02-01 18:44 ` Mathieu Poirier
2021-02-18 4:23 ` Anshuman Khandual
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