[EXT] Re: [PATCH v6 1/6] eal: trace: add trace point emit for blob
Ferruh Yigit
ferruh.yigit at amd.com
Wed Jan 25 17:09:33 CET 2023
On 1/25/2023 3:02 PM, Ankur Dwivedi wrote:
>
>>
>> ----------------------------------------------------------------------
>> On 1/20/2023 8:40 AM, Ankur Dwivedi wrote:
>>> Adds a trace point emit function for capturing a blob. The blob
>>> captures the length passed by the application followed by the array.
>>>
>>> The maximum blob bytes which can be captured is bounded by
>>> RTE_TRACE_BLOB_LEN_MAX macro. The value for max blob length macro is
>>> 64 bytes. If the length is less than 64 the remaining trailing bytes
>>> are set to zero.
>>>
>>> This patch also adds test case for emit blob tracepoint function.
>>>
>>> Signed-off-by: Ankur Dwivedi <adwivedi at marvell.com>
>>> ---
>>> app/test/test_trace.c | 11 ++++++++
>>> doc/guides/prog_guide/trace_lib.rst | 12 ++++++++
>>> lib/eal/common/eal_common_trace_points.c | 2 ++
>>> lib/eal/include/rte_eal_trace.h | 6 ++++
>>> lib/eal/include/rte_trace_point.h | 32 ++++++++++++++++++++++
>>> lib/eal/include/rte_trace_point_register.h | 9 ++++++
>>> lib/eal/version.map | 3 ++
>>> 7 files changed, 75 insertions(+)
>>>
>>> diff --git a/app/test/test_trace.c b/app/test/test_trace.c index
>>> 6bedf14024..ad4a394a29 100644
>>> --- a/app/test/test_trace.c
>>> +++ b/app/test/test_trace.c
>>> @@ -4,6 +4,7 @@
>>>
>>> #include <rte_eal_trace.h>
>>> #include <rte_lcore.h>
>>> +#include <rte_random.h>
>>> #include <rte_trace.h>
>>>
>>> #include "test.h"
>>> @@ -177,7 +178,12 @@ test_fp_trace_points(void) static int
>>> test_generic_trace_points(void)
>>> {
>>> + uint8_t arr[RTE_TRACE_BLOB_LEN_MAX];
>>> int tmp;
>>> + int i;
>>> +
>>> + for (i = 0; i < RTE_TRACE_BLOB_LEN_MAX; i++)
>>> + arr[i] = i;
>>>
>>> rte_eal_trace_generic_void();
>>> rte_eal_trace_generic_u64(0x10000000000000);
>>> @@ -195,6 +201,11 @@ test_generic_trace_points(void)
>>> rte_eal_trace_generic_ptr(&tmp);
>>> rte_eal_trace_generic_str("my string");
>>> rte_eal_trace_generic_size_t(sizeof(void *));
>>> + rte_eal_trace_generic_blob(arr, 0);
>>> + rte_eal_trace_generic_blob(arr, 17);
>>> + rte_eal_trace_generic_blob(arr, RTE_TRACE_BLOB_LEN_MAX);
>>> + rte_eal_trace_generic_blob(arr, rte_rand() %
>>> + RTE_TRACE_BLOB_LEN_MAX);
>>> RTE_EAL_TRACE_GENERIC_FUNC;
>>>
>>> return TEST_SUCCESS;
>>> diff --git a/doc/guides/prog_guide/trace_lib.rst
>>> b/doc/guides/prog_guide/trace_lib.rst
>>> index 9a8f38073d..3e0ea5835c 100644
>>> --- a/doc/guides/prog_guide/trace_lib.rst
>>> +++ b/doc/guides/prog_guide/trace_lib.rst
>>> @@ -352,3 +352,15 @@ event ID.
>>> The ``packet.header`` and ``packet.context`` will be written in the
>>> slow path at the time of trace memory creation. The ``trace.header``
>>> and trace payload will be emitted when the tracepoint function is invoked.
>>> +
>>> +Limitations
>>> +-----------
>>> +
>>> +- The ``rte_trace_point_emit_blob()`` function can capture a maximum
>>> +blob of
>>> + length ``RTE_TRACE_BLOB_LEN_MAX`` bytes. The application can call
>>> + ``rte_trace_point_emit_blob()`` multiple times with length less
>>> +than or equal to
>>> + ``RTE_TRACE_BLOB_LEN_MAX``, if it needs to capture more than
>>> +``RTE_TRACE_BLOB_LEN_MAX``
>>> + bytes.
>>> +- If the length passed to the ``rte_trace_point_emit_blob()`` is less
>>> +than
>>> + ``RTE_TRACE_BLOB_LEN_MAX``, then the trailing
>>> +``(RTE_TRACE_BLOB_LEN_MAX - len)``
>>> + bytes in the trace are set to zero.
>>> diff --git a/lib/eal/common/eal_common_trace_points.c
>>> b/lib/eal/common/eal_common_trace_points.c
>>> index 0b0b254615..051f89809c 100644
>>> --- a/lib/eal/common/eal_common_trace_points.c
>>> +++ b/lib/eal/common/eal_common_trace_points.c
>>> @@ -40,6 +40,8 @@
>> RTE_TRACE_POINT_REGISTER(rte_eal_trace_generic_size_t,
>>> lib.eal.generic.size_t)
>>> RTE_TRACE_POINT_REGISTER(rte_eal_trace_generic_func,
>>> lib.eal.generic.func)
>>> +RTE_TRACE_POINT_REGISTER(rte_eal_trace_generic_blob,
>>> + lib.eal.generic.blob)
>>>
>>> RTE_TRACE_POINT_REGISTER(rte_eal_trace_alarm_set,
>>> lib.eal.alarm.set)
>>> diff --git a/lib/eal/include/rte_eal_trace.h
>>> b/lib/eal/include/rte_eal_trace.h index 5ef4398230..e0b836eb2f 100644
>>> --- a/lib/eal/include/rte_eal_trace.h
>>> +++ b/lib/eal/include/rte_eal_trace.h
>>> @@ -143,6 +143,12 @@ RTE_TRACE_POINT(
>>> rte_trace_point_emit_string(func);
>>> )
>>>
>>> +RTE_TRACE_POINT(
>>> + rte_eal_trace_generic_blob,
>>> + RTE_TRACE_POINT_ARGS(void *in, uint8_t len),
>>> + rte_trace_point_emit_blob(in, len);
>>> +)
>>> +
>>> #define RTE_EAL_TRACE_GENERIC_FUNC
>>> rte_eal_trace_generic_func(__func__)
>>>
>>> /* Interrupt */
>>> diff --git a/lib/eal/include/rte_trace_point.h
>>> b/lib/eal/include/rte_trace_point.h
>>> index 0f8700974f..aca8344dbf 100644
>>> --- a/lib/eal/include/rte_trace_point.h
>>> +++ b/lib/eal/include/rte_trace_point.h
>>> @@ -144,6 +144,16 @@ _tp _args \
>>> #define rte_trace_point_emit_ptr(val)
>>> /** Tracepoint function payload for string datatype */ #define
>>> rte_trace_point_emit_string(val)
>>> +/**
>>> + * Tracepoint function to capture a blob.
>>> + *
>>> + * @param val
>>> + * Pointer to the array to be captured.
>>> + * @param len
>>> + * Length to be captured. The maximum supported length is
>>> + * RTE_TRACE_BLOB_LEN_MAX bytes.
>>> + */
>>> +#define rte_trace_point_emit_blob(val, len)
>>>
>>
>> This is just for doxygen right, why doxygen comments are not above the actual
>> macros but there is a separate #if block for it?
>
> The actual macro is within a #ifndef __DOXYGEN__ block. I think that is the reason for including
> Doxygen comments here.
Thanks for confirming.
Why comments are not as part of actual macro, but there is a separate
'#ifdef __DOXYGEN__' block?
>>
>>> #endif /* __DOXYGEN__ */
>>>
>>> @@ -152,6 +162,9 @@ _tp _args \
>>> /** @internal Macro to define event header size. */ #define
>>> __RTE_TRACE_EVENT_HEADER_SZ sizeof(uint64_t)
>>>
>>> +/** Macro to define maximum emit length of blob. */ #define
>>> +RTE_TRACE_BLOB_LEN_MAX 64
>>> +
>>> /**
>>> * Enable recording events of the given tracepoint in the trace buffer.
>>> *
>>> @@ -374,12 +387,31 @@ do { \
>>> mem = RTE_PTR_ADD(mem, __RTE_TRACE_EMIT_STRING_LEN_MAX);
>> \ } while
>>> (0)
>>>
>>> +#define rte_trace_point_emit_blob(in, len) \ do { \
>>> + if (unlikely(in == NULL)) \
>>> + return; \
>>> + if (len > RTE_TRACE_BLOB_LEN_MAX) \
>>> + len = RTE_TRACE_BLOB_LEN_MAX; \
>>> + __rte_trace_point_emit(len, uint8_t); \
>>> + memcpy(mem, in, len); \
>>> + mem = RTE_PTR_ADD(mem, len); \
>>> + memset(mem, 0, RTE_TRACE_BLOB_LEN_MAX - len); \
>>> + mem = RTE_PTR_ADD(mem, RTE_TRACE_BLOB_LEN_MAX - len); \
>>
>>
>> Is first memset later memcpy not done because of performance concerns?
>
> The memset sets to 0 the unused bytes (RTE_TRACE_BLOB_LEN_MAX - len). So memset is done after memcpy.
yep, I can see what is done.
Question is, you can do more simply:
memset(mem, 0, RTE_TRACE_BLOB_LEN_MAX);
memcpy(mem, in, len);
mem = RTE_PTR_ADD(mem, RTE_TRACE_BLOB_LEN_MAX - len);
Why did you prefer the implementation you did, intentionally? If so what
is the intention, performance concerns?
btw, I want to remind that size of the 'len' can be max 64 bytes.
>>
>>> +} while (0)
>>> +
>>> #else
>>>
>>> #define __rte_trace_point_emit_header_generic(t) RTE_SET_USED(t)
>>> #define __rte_trace_point_emit_header_fp(t) RTE_SET_USED(t) #define
>>> __rte_trace_point_emit(in, type) RTE_SET_USED(in) #define
>>> rte_trace_point_emit_string(in) RTE_SET_USED(in)
>>> +#define rte_trace_point_emit_blob(in, len) \ do { \
>>> + RTE_SET_USED(in); \
>>> + RTE_SET_USED(len); \
>>> +} while (0)
>>> +
>>>
>>> #endif /* ALLOW_EXPERIMENTAL_API */
>>> #endif /* _RTE_TRACE_POINT_REGISTER_H_ */ diff --git
>>> a/lib/eal/include/rte_trace_point_register.h
>>> b/lib/eal/include/rte_trace_point_register.h
>>> index a32f4d731b..7efbac8a72 100644
>>> --- a/lib/eal/include/rte_trace_point_register.h
>>> +++ b/lib/eal/include/rte_trace_point_register.h
>>> @@ -47,6 +47,15 @@ do { \
>>> RTE_STR(in)"[32]", "string_bounded_t"); \ } while (0)
>>>
>>> +#define rte_trace_point_emit_blob(in, len) \ do { \
>>> + RTE_SET_USED(in); \
>>> + __rte_trace_point_emit(len, uint8_t); \
>>> + __rte_trace_point_emit_field(RTE_TRACE_BLOB_LEN_MAX, \
>>> + RTE_STR(in)"["RTE_STR(RTE_TRACE_BLOB_LEN_MAX)"]", \
>>> + RTE_STR(uint8_t)); \
>>> +} while (0)
>>> +
>>
>> Why this macro defined here again, it is also defined in 'rte_trace_point.h'
>> already?
>> Is it because of 'register_fn()' in '__rte_trace_point_register()'?
>
> Yes the register happens in this function.
You are not really answering questions.
There are three copy of '#define rte_trace_point_emit_blob(in, len)' one
of them is for doxygen comment, please explain why there are two more
copies of it?
>>
>>> #ifdef __cplusplus
>>> }
>>> #endif
>>> diff --git a/lib/eal/version.map b/lib/eal/version.map index
>>> 7ad12a7dc9..67be24686a 100644
>>> --- a/lib/eal/version.map
>>> +++ b/lib/eal/version.map
>>> @@ -440,6 +440,9 @@ EXPERIMENTAL {
>>> rte_thread_detach;
>>> rte_thread_equal;
>>> rte_thread_join;
>>> +
>>> + # added in 23.03
>>> + __rte_eal_trace_generic_blob;
>>
>> This is not a function but a trace object.
>> I guess it was agreed that trace object not need to be exported, and trace can
>> be found by name?
>
> Yes the export in version.map can be removed. Will remove it in next patch series.
ack.
Will there be a separate patch to remove existing symbols? Although I am
not sure if it will be ABI break.
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