Re: (subset) [PATCH v6 00/17] coresight: Use per-sink trace ID maps for Perf sessions

[Suzuki K Poulose]

On Mon, 22 Jul 2024 11:11:42 +0100, James Clark wrote:
> This will allow sessions with more than CORESIGHT_TRACE_IDS_MAX ETMs
> as long as there are fewer than that many ETMs connected to each sink.
> 
> Each sink owns its own trace ID map, and any Perf session connecting to
> that sink will allocate from it, even if the sink is currently in use by
> other users. This is similar to the existing behavior where the dynamic
> trace IDs are constant as long as there is any concurrent Perf session
> active. It's not completely optimal because slightly more IDs will be
> used than necessary, but the optimal solution involves tracking the PIDs
> of each session and allocating ID maps based on the session owner. This
> is difficult to do with the combination of per-thread and per-cpu modes
> and some scheduling issues. The complexity of this isn't likely to worth
> it because even with multiple users they'd just see a difference in the
> ordering of ID allocations rather than hitting any limits (unless the
> hardware does have too many ETMs connected to one sink).
> 
> [...]

Applied, the kernel driver changes to coresight/next. Thanks!

[09/17] coresight: Remove unused ETM Perf stubs
        https://git.kernel.org/coresight/c/34172002bdac
[10/17] coresight: Clarify comments around the PID of the sink owner
        https://git.kernel.org/coresight/c/eda1d11979c0
[11/17] coresight: Move struct coresight_trace_id_map to common header
        https://git.kernel.org/coresight/c/acb0184fe9bc
[12/17] coresight: Expose map arguments in trace ID API
        https://git.kernel.org/coresight/c/7e52877868ae
[13/17] coresight: Make CPU id map a property of a trace ID map
        https://git.kernel.org/coresight/c/d53c8253c782
[14/17] coresight: Use per-sink trace ID maps for Perf sessions
        https://git.kernel.org/coresight/c/5ad628a76176
[15/17] coresight: Remove pending trace ID release mechanism
        https://git.kernel.org/coresight/c/de0029fdde86
[16/17] coresight: Emit sink ID in the HW_ID packets
        https://git.kernel.org/coresight/c/487eec8da80a
[17/17] coresight: Make trace ID map spinlock local to the map
        https://git.kernel.org/coresight/c/988d40a4d4e7

Best regards,
-- 
Suzuki K Poulose <suzuki.poulose@xxxxxxx>