diff options
| -rw-r--r-- | Documentation/technical/api-trace2.txt | 8 | ||||
| -rw-r--r-- | trace2.c | 2 | ||||
| -rw-r--r-- | trace2.h | 10 | ||||
| -rw-r--r-- | trace2/tr2_tls.c | 6 | ||||
| -rw-r--r-- | trace2/tr2_tls.h | 18 |
5 files changed, 24 insertions, 20 deletions
diff --git a/Documentation/technical/api-trace2.txt b/Documentation/technical/api-trace2.txt index 2afa28bb5a..431d424f9d 100644 --- a/Documentation/technical/api-trace2.txt +++ b/Documentation/technical/api-trace2.txt @@ -685,8 +685,8 @@ The "exec_id" field is a command-unique id and is only useful if the `"thread_start"`:: This event is generated when a thread is started. It is - generated from *within* the new thread's thread-proc (for TLS - reasons). + generated from *within* the new thread's thread-proc (because + it needs to access data in the thread's thread-local storage). + ------------ { @@ -698,7 +698,7 @@ The "exec_id" field is a command-unique id and is only useful if the `"thread_exit"`:: This event is generated when a thread exits. It is generated - from *within* the thread's thread-proc (for TLS reasons). + from *within* the thread's thread-proc. + ------------ { @@ -1206,7 +1206,7 @@ worked on 508 items at offset 2032. Thread "th04" worked on 508 items at offset 508. + This example also shows that thread names are assigned in a racy manner -as each thread starts and allocates TLS storage. +as each thread starts. Config (def param) Events:: @@ -52,7 +52,7 @@ static struct tr2_tgt *tr2_tgt_builtins[] = * Force (rather than lazily) initialize any of the requested * builtin TRACE2 targets at startup (and before we've seen an * actual TRACE2 event call) so we can see if we need to setup - * the TR2 and TLS machinery. + * private data structures and thread-local storage. * * Return the number of builtin targets enabled. */ @@ -73,8 +73,7 @@ void trace2_initialize_clock(void); /* * Initialize TRACE2 tracing facility if any of the builtin TRACE2 * targets are enabled in the system config or the environment. - * This includes setting up the Trace2 thread local storage (TLS). - * Emits a 'version' message containing the version of git + * This emits a 'version' message containing the version of git * and the Trace2 protocol. * * This function should be called from `main()` as early as possible in @@ -302,7 +301,8 @@ void trace2_exec_result_fl(const char *file, int line, int exec_id, int code); /* * Emit a 'thread_start' event. This must be called from inside the - * thread-proc to set up the trace2 TLS data for the thread. + * thread-proc to allow the thread to create its own thread-local + * storage. * * Thread names should be descriptive, like "preload_index". * Thread names will be decorated with an instance number automatically. @@ -315,8 +315,8 @@ void trace2_thread_start_fl(const char *file, int line, /* * Emit a 'thread_exit' event. This must be called from inside the - * thread-proc to report thread-specific data and cleanup TLS data - * for the thread. + * thread-proc so that the thread can access and clean up its + * thread-local storage. */ void trace2_thread_exit_fl(const char *file, int line); diff --git a/trace2/tr2_tls.c b/trace2/tr2_tls.c index 7da94aba52..8d2182fbdb 100644 --- a/trace2/tr2_tls.c +++ b/trace2/tr2_tls.c @@ -69,9 +69,9 @@ struct tr2tls_thread_ctx *tr2tls_get_self(void) ctx = pthread_getspecific(tr2tls_key); /* - * If the thread-proc did not call trace2_thread_start(), we won't - * have any TLS data associated with the current thread. Fix it - * here and silently continue. + * If the current thread's thread-proc did not call + * trace2_thread_start(), then the thread will not have any + * thread-local storage. Create it now and silently continue. */ if (!ctx) ctx = tr2tls_create_self("unknown", getnanotime() / 1000); diff --git a/trace2/tr2_tls.h b/trace2/tr2_tls.h index a90bd639d4..1297509fd2 100644 --- a/trace2/tr2_tls.h +++ b/trace2/tr2_tls.h @@ -4,6 +4,12 @@ #include "strbuf.h" /* + * Notice: the term "TLS" refers to "thread-local storage" in the + * Trace2 source files. This usage is borrowed from GCC and Windows. + * There is NO relation to "transport layer security". + */ + +/* * Arbitry limit for thread names for column alignment. */ #define TR2_MAX_THREAD_NAME (24) @@ -17,9 +23,7 @@ struct tr2tls_thread_ctx { }; /* - * Create TLS data for the current thread. This gives us a place to - * put per-thread data, such as thread start time, function nesting - * and a per-thread label for our messages. + * Create thread-local storage for the current thread. * * We assume the first thread is "main". Other threads are given * non-zero thread-ids to help distinguish messages from concurrent @@ -35,7 +39,7 @@ struct tr2tls_thread_ctx *tr2tls_create_self(const char *thread_name, uint64_t us_thread_start); /* - * Get our TLS data. + * Get the thread-local storage pointer of the current thread. */ struct tr2tls_thread_ctx *tr2tls_get_self(void); @@ -45,7 +49,7 @@ struct tr2tls_thread_ctx *tr2tls_get_self(void); int tr2tls_is_main_thread(void); /* - * Free our TLS data. + * Free the current thread's thread-local storage. */ void tr2tls_unset_self(void); @@ -81,12 +85,12 @@ uint64_t tr2tls_region_elasped_self(uint64_t us); uint64_t tr2tls_absolute_elapsed(uint64_t us); /* - * Initialize the tr2 TLS system. + * Initialize thread-local storage for Trace2. */ void tr2tls_init(void); /* - * Free all tr2 TLS resources. + * Free all Trace2 thread-local storage resources. */ void tr2tls_release(void); |