From: Leo Yan <leo.yan@arm.com>
To: James Clark <james.clark@linaro.org>
Cc: Suzuki K Poulose <suzuki.poulose@arm.com>,
Mike Leach <mike.leach@arm.com>, Suyash Mahar <smahar@meta.com>,
Yeoreum Yun <yeoreum.yun@arm.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Qi Liu <liuqi115@huawei.com>, Junhao He <hejunhao3@huawei.com>,
coresight@lists.linaro.org, linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, Jonathan Cameron <jic23@kernel.org>
Subject: Re: [PATCH v3 4/8] coresight: tmc-etr: Prevent per-thread events from sharing a sink
Date: Thu, 13 Aug 2026 17:05:04 +0100 [thread overview]
Message-ID: <20260813160504.GC8904@e132581.arm.com> (raw)
In-Reply-To: <20260728-james-cs-multiple-per-threads-v3-4-6aee7579f1dc@linaro.org>
On Tue, Jul 28, 2026 at 04:00:16PM +0100, James Clark wrote:
[...]
> The identity and compatibility of a session are determined by the owning
> process, the target process, and the inheritance settings together.
Could you elaborate a bit on the session model you are trying to support
here?
My understanding of a legacy sink such as ETR/ETF is that it can be
owned by only one perf session at a time. Multiple events belonging to
that session may use the sink, but an attempt from another perf session
should be rejected with -EBUSY.
For per-thread mode, I wonder if we could support _only_ non-inherited
events. In that case, we would not need to determine compatibility based
on the target process and inheritance settings.
From the patch, it seems trying to support a more flexible model, where
an already active legacy sink can also be shared by another perf session
and also support inherit mode for child events?
Thanks,
Leo
next prev parent reply other threads:[~2026-08-13 16:05 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-07-28 15:00 [PATCH v3 0/8] coresight: Prevent per-thread events from sharing a sink James Clark
2026-07-28 15:00 ` [PATCH v3 1/8] coresight: tmc-etr: Don't stop Perf cleanup for active sysfs reads James Clark
2026-08-12 16:45 ` Leo Yan
2026-08-13 9:02 ` James Clark
2026-07-28 15:00 ` [PATCH v3 2/8] coresight: configfs: Don't assume active until cscfg_mgr is set James Clark
2026-08-13 9:09 ` Leo Yan
2026-08-13 9:24 ` James Clark
2026-07-28 15:00 ` [PATCH v3 3/8] coresight: etm-perf: Flush workqueue before unloading module James Clark
2026-08-13 14:19 ` Leo Yan
2026-07-28 15:00 ` [PATCH v3 4/8] coresight: tmc-etr: Prevent per-thread events from sharing a sink James Clark
2026-08-13 16:05 ` Leo Yan [this message]
2026-07-28 15:00 ` [PATCH v3 5/8] coresight: tmc-etr: Use session ID for buffer ownership James Clark
2026-07-28 15:00 ` [PATCH v3 6/8] coresight: tmc-etf: Prevent per-thread events from sharing a sink James Clark
2026-07-28 15:00 ` [PATCH v3 7/8] coresight: etb10: " James Clark
2026-07-28 15:00 ` [PATCH v3 8/8] coresight: ultrasoc-smb: " James Clark
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