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Message-ID: <e6b436f0-3d1b-47c4-836f-5d5a2a0a0a31@arm.com>
Date: Thu, 6 Jun 2024 15:10:08 +0100
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Subject: Re: [PATCH v2 11/16] coresight: Expose map arguments in trace ID API
To: Suzuki K Poulose <suzuki.poulose@arm.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>,
 Maxime Coquelin <mcoquelin.stm32@gmail.com>,
 Alexandre Torgue <alexandre.torgue@foss.st.com>,
 Peter Zijlstra <peterz@infradead.org>, Ingo Molnar <mingo@redhat.com>,
 Arnaldo Carvalho de Melo <acme@kernel.org>,
 Namhyung Kim <namhyung@kernel.org>, Mark Rutland <mark.rutland@arm.com>,
 Jiri Olsa <jolsa@kernel.org>, Ian Rogers <irogers@google.com>,
 Adrian Hunter <adrian.hunter@intel.com>, John Garry
 <john.g.garry@oracle.com>, Will Deacon <will@kernel.org>,
 linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
 linux-stm32@st-md-mailman.stormreply.com, linux-perf-users@vger.kernel.org,
 coresight@lists.linaro.org, gankulkarni@os.amperecomputing.com,
 mike.leach@linaro.org, leo.yan@linux.dev, anshuman.khandual@arm.com
References: <20240604143030.519906-1-james.clark@arm.com>
 <20240604143030.519906-12-james.clark@arm.com>
 <d8b016dc-2ab0-442b-97b9-00ae352553c6@arm.com>
Content-Language: en-US
From: James Clark <james.clark@arm.com>
In-Reply-To: <d8b016dc-2ab0-442b-97b9-00ae352553c6@arm.com>
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On 06/06/2024 14:50, Suzuki K Poulose wrote:
> On 04/06/2024 15:30, James Clark wrote:
>> The trace ID API is currently hard coded to always use the global map.
>> Add public versions that allow the map to be passed in so that Perf
>> mode can use per-sink maps. Keep the non-map versions so that sysfs
>> mode can continue to use the default global map.
>>
>> System ID functions are unchanged because they will always use the
>> default map.
>>
>> Signed-off-by: James Clark <james.clark@arm.com>
>> ---
>>   .../hwtracing/coresight/coresight-trace-id.c  | 36 ++++++++++++++-----
>>   .../hwtracing/coresight/coresight-trace-id.h  | 20 +++++++++--
>>   2 files changed, 45 insertions(+), 11 deletions(-)
>>
>> diff --git a/drivers/hwtracing/coresight/coresight-trace-id.c
>> b/drivers/hwtracing/coresight/coresight-trace-id.c
>> index 19005b5b4dc4..5561989a03fa 100644
>> --- a/drivers/hwtracing/coresight/coresight-trace-id.c
>> +++ b/drivers/hwtracing/coresight/coresight-trace-id.c
>> @@ -12,7 +12,7 @@
>>     #include "coresight-trace-id.h"
>>   -/* Default trace ID map. Used on systems that don't require per
>> sink mappings */
>> +/* Default trace ID map. Used in sysfs mode and for system sources */
>>   static struct coresight_trace_id_map id_map_default;
>>     /* maintain a record of the mapping of IDs and pending releases
>> per cpu */
>> @@ -47,7 +47,7 @@ static void coresight_trace_id_dump_table(struct
>> coresight_trace_id_map *id_map,
>>   #endif
>>     /* unlocked read of current trace ID value for given CPU */
>> -static int _coresight_trace_id_read_cpu_id(int cpu)
>> +static int _coresight_trace_id_read_cpu_id(int cpu, struct
>> coresight_trace_id_map *id_map)
>>   {
>>       return atomic_read(&per_cpu(cpu_id, cpu));
>>   }
>> @@ -152,7 +152,7 @@ static void
>> coresight_trace_id_release_all_pending(void)
>>       DUMP_ID_MAP(id_map);
>>   }
>>   -static int coresight_trace_id_map_get_cpu_id(int cpu, struct
>> coresight_trace_id_map *id_map)
>> +static int _coresight_trace_id_get_cpu_id(int cpu, struct
>> coresight_trace_id_map *id_map)
>>   {
>>       unsigned long flags;
>>       int id;
>> @@ -160,7 +160,7 @@ static int coresight_trace_id_map_get_cpu_id(int
>> cpu, struct coresight_trace_id_
>>       spin_lock_irqsave(&id_map_lock, flags);
> 
> Could we also reduce the contention on the id_map_lock, by moving the
> spinlock per map ? It can be a separate patch.
> 
> This patch as such looks good to me.
> 
> Suzuki
> 
> 

Good point yes we can do that.

>>         /* check for existing allocation for this CPU */
>> -    id = _coresight_trace_id_read_cpu_id(cpu);
>> +    id = _coresight_trace_id_read_cpu_id(cpu, id_map);
>>       if (id)
>>           goto get_cpu_id_clr_pend;
>>   @@ -196,13 +196,13 @@ static int
>> coresight_trace_id_map_get_cpu_id(int cpu, struct coresight_trace_id_
>>       return id;
>>   }
>>   -static void coresight_trace_id_map_put_cpu_id(int cpu, struct
>> coresight_trace_id_map *id_map)
>> +static void _coresight_trace_id_put_cpu_id(int cpu, struct
>> coresight_trace_id_map *id_map)
>>   {
>>       unsigned long flags;
>>       int id;
>>         /* check for existing allocation for this CPU */
>> -    id = _coresight_trace_id_read_cpu_id(cpu);
>> +    id = _coresight_trace_id_read_cpu_id(cpu, id_map);
>>       if (!id)
>>           return;
>>   @@ -254,22 +254,40 @@ static void
>> coresight_trace_id_map_put_system_id(struct coresight_trace_id_map *
>>     int coresight_trace_id_get_cpu_id(int cpu)
>>   {
>> -    return coresight_trace_id_map_get_cpu_id(cpu, &id_map_default);
>> +    return _coresight_trace_id_get_cpu_id(cpu, &id_map_default);
>>   }
>>   EXPORT_SYMBOL_GPL(coresight_trace_id_get_cpu_id);
>>   +int coresight_trace_id_get_cpu_id_map(int cpu, struct
>> coresight_trace_id_map *id_map)
>> +{
>> +    return _coresight_trace_id_get_cpu_id(cpu, id_map);
>> +}
>> +EXPORT_SYMBOL_GPL(coresight_trace_id_get_cpu_id_map);
>> +
>>   void coresight_trace_id_put_cpu_id(int cpu)
>>   {
>> -    coresight_trace_id_map_put_cpu_id(cpu, &id_map_default);
>> +    _coresight_trace_id_put_cpu_id(cpu, &id_map_default);
>>   }
>>   EXPORT_SYMBOL_GPL(coresight_trace_id_put_cpu_id);
>>   +void coresight_trace_id_put_cpu_id_map(int cpu, struct
>> coresight_trace_id_map *id_map)
>> +{
>> +    _coresight_trace_id_put_cpu_id(cpu, id_map);
>> +}
>> +EXPORT_SYMBOL_GPL(coresight_trace_id_put_cpu_id_map);
>> +
>>   int coresight_trace_id_read_cpu_id(int cpu)
>>   {
>> -    return _coresight_trace_id_read_cpu_id(cpu);
>> +    return _coresight_trace_id_read_cpu_id(cpu, &id_map_default);
>>   }
>>   EXPORT_SYMBOL_GPL(coresight_trace_id_read_cpu_id);
>>   +int coresight_trace_id_read_cpu_id_map(int cpu, struct
>> coresight_trace_id_map *id_map)
>> +{
>> +    return _coresight_trace_id_read_cpu_id(cpu, id_map);
>> +}
>> +EXPORT_SYMBOL_GPL(coresight_trace_id_read_cpu_id_map);
>> +
>>   int coresight_trace_id_get_system_id(void)
>>   {
>>       return coresight_trace_id_map_get_system_id(&id_map_default);
>> diff --git a/drivers/hwtracing/coresight/coresight-trace-id.h
>> b/drivers/hwtracing/coresight/coresight-trace-id.h
>> index 49438a96fcc6..840babdd0794 100644
>> --- a/drivers/hwtracing/coresight/coresight-trace-id.h
>> +++ b/drivers/hwtracing/coresight/coresight-trace-id.h
>> @@ -42,8 +42,6 @@
>>   #define IS_VALID_CS_TRACE_ID(id)    \
>>       ((id > CORESIGHT_TRACE_ID_RES_0) && (id <
>> CORESIGHT_TRACE_ID_RES_TOP))
>>   -/* Allocate and release IDs for a single default trace ID map */
>> -
>>   /**
>>    * Read and optionally allocate a CoreSight trace ID and associate
>> with a CPU.
>>    *
>> @@ -59,6 +57,12 @@
>>    */
>>   int coresight_trace_id_get_cpu_id(int cpu);
>>   +/**
>> + * Version of coresight_trace_id_get_cpu_id() that allows the ID map
>> to operate
>> + * on to be provided.
>> + */
>> +int coresight_trace_id_get_cpu_id_map(int cpu, struct
>> coresight_trace_id_map *id_map);
>> +
>>   /**
>>    * Release an allocated trace ID associated with the CPU.
>>    *
>> @@ -72,6 +76,12 @@ int coresight_trace_id_get_cpu_id(int cpu);
>>    */
>>   void coresight_trace_id_put_cpu_id(int cpu);
>>   +/**
>> + * Version of coresight_trace_id_put_cpu_id() that allows the ID map
>> to operate
>> + * on to be provided.
>> + */
>> +void coresight_trace_id_put_cpu_id_map(int cpu, struct
>> coresight_trace_id_map *id_map);
>> +
>>   /**
>>    * Read the current allocated CoreSight Trace ID value for the CPU.
>>    *
>> @@ -92,6 +102,12 @@ void coresight_trace_id_put_cpu_id(int cpu);
>>    */
>>   int coresight_trace_id_read_cpu_id(int cpu);
>>   +/**
>> + * Version of coresight_trace_id_read_cpu_id() that allows the ID map
>> to operate
>> + * on to be provided.
>> + */
>> +int coresight_trace_id_read_cpu_id_map(int cpu, struct
>> coresight_trace_id_map *id_map);
>> +
>>   /**
>>    * Allocate a CoreSight trace ID for a system component.
>>    *
>