v4: Re: [PATCH v7 00/15] coresight: Add new API to allocate trace source ID values

[Suzuki K Poulose]

Arnaldo

Gentle ping


On 31/01/2023 11:49, Suzuki K Poulose wrote:
> Hi Arnaldo
>
> On 24/01/2023 11:36, Suzuki K Poulose wrote:
> > Hi Arnaldo
> >
> > Gentle ping.
> >
> > On 19/01/2023 12:00, Suzuki K Poulose wrote:
> > > Hi Arnaldo,
> > >
> > > On 16/01/2023 12:49, Mike Leach wrote:
> > > > The current method for allocating trace source ID values to sources is
> > > > to use a fixed algorithm for CPU based sources of (cpu_num * 2 + 0x10).
> > > > The STM is allocated ID 0x1.
> > > >
> > > > This fixed algorithm is used in both the CoreSight driver code, and by
> > > > perf when writing the trace metadata in the AUXTRACE_INFO record.
> > > >
> > > > The method needs replacing as currently:-
> > > > 1. It is inefficient in using available IDs.
> > > > 2. Does not scale to larger systems with many cores and the algorithm
> > > > has no limits so will generate invalid trace IDs for cpu number > 44.
> > > >
> > > > Additionally requirements to allocate additional system IDs on some
> > > > systems have been seen.
> > > >
> > > > This patch set  introduces an API that allows the allocation of 
> > > > trace IDs
> > > > in a dynamic manner.
> > > >
> > > > Architecturally reserved IDs are never allocated, and the system is
> > > > limited to allocating only valid IDs.
> > > >
> > > > Each of the current trace sources ETM3.x, ETM4.x and STM is updated 
> > > > to use
> > > > the new API.
> > > >
> > > > For the ETMx.x devices IDs are allocated on certain events
> > > > a) When using sysfs, an ID will be allocated on hardware enable, or 
> > > > a read of
> > > > sysfs TRCTRACEID register and freed when the sysfs reset is written.
> > > >
> > > > b) When using perf, ID is allocated on during setup AUX event, and 
> > > > freed on
> > > > event free. IDs are communicated using the AUX_OUTPUT_HW_ID packet.
> > > > The ID allocator is notified when perf sessions start and stop
> > > > so CPU based IDs are kept constant throughout any perf session.
> > > >
> > > >
> > > > Note: This patchset breaks some backward compatibility for perf 
> > > > record and
> > > > perf report.
> > > >
> > > > The version of the AUXTRACE_INFO has been updated to reflect the 
> > > > fact that
> > > > the trace source IDs are generated differently. This will
> > > > mean older versions of perf report cannot decode the newer file.
> > > >
> > > > Appies to coresight/next
> >
> > ...
> >
> > > > Mike Leach (15):
> > > >    coresight: trace-id: Add API to dynamically assign Trace ID values
> > > >    coresight: Remove obsolete Trace ID unniqueness checks
> > > >    coresight: perf: traceid: Add perf ID allocation and notifiers
> > > >    coresight: stm: Update STM driver to use Trace ID API
> > > >    coresight: etm4x: Update ETM4 driver to use Trace ID API
> > > >    coresight: etm3x: Update ETM3 driver to use Trace ID API
> > > >    coresight: etmX.X: stm: Remove trace_id() callback
> > > >    coresight: trace id: Remove legacy get trace ID function.
> > > >    perf: cs-etm: Move mapping of Trace ID and cpu into helper function
> > > >    perf: cs-etm: Update record event to use new Trace ID protocol
> > > >    kernel: events: Export perf_report_aux_output_id()
> > > >    perf: cs-etm: Handle PERF_RECORD_AUX_OUTPUT_HW_ID packet
> > > >    coresight: events: PERF_RECORD_AUX_OUTPUT_HW_ID used for Trace ID
> > > >    coresight: trace-id: Add debug & test macros to Trace ID allocation
> > > >    coresight: etm3x: docs: Alter sysfs documentation for trace id 
> > > > updates
> > >
> > > I have pushed the kernel patches on this series to coresight tree 
> > > next[0].
> > >
> > > I will be sending them out to Greg for v6.3. Please could you queue the
> > > perf tool changes in the series ? i.e., Patches 9,10 and 12.
> > >
> > >
> > > [0] 
> > > https://git.kernel.org/pub/scm/linux/kernel/git/coresight/linux.git/log/?h=next
> >
> > Please could you pick up the perf tool changes above ?
>
> Please could you confirm if you are able to queue the perf tool changes 
> ? Or would you like me route it via coresight tree ?
>
> Kind regards
> Suzuki


Suzuki