diff options
author | Steven Rostedt (VMware) <rostedt@goodmis.org> | 2020-08-18 16:57:52 +0300 |
---|---|---|
committer | Ingo Molnar <mingo@kernel.org> | 2020-09-01 10:58:06 +0300 |
commit | d25e37d89dd2f41d7acae0429039d2f0ae8b4a07 (patch) | |
tree | 16e6d52b374b3907e51dd3a96b30f3c427f9a55f /include/linux | |
parent | a945c8345ec0decb2f1a7f19a8c5e60bcb1dd1eb (diff) | |
download | linux-d25e37d89dd2f41d7acae0429039d2f0ae8b4a07.tar.xz |
tracepoint: Optimize using static_call()
Currently the tracepoint site will iterate a vector and issue indirect
calls to however many handlers are registered (ie. the vector is
long).
Using static_call() it is possible to optimize this for the common
case of only having a single handler registered. In this case the
static_call() can directly call this handler. Otherwise, if the vector
is longer than 1, call a function that iterates the whole vector like
the current code.
[peterz: updated to new interface]
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/20200818135805.279421092@infradead.org
Diffstat (limited to 'include/linux')
-rw-r--r-- | include/linux/tracepoint-defs.h | 5 | ||||
-rw-r--r-- | include/linux/tracepoint.h | 86 |
2 files changed, 66 insertions, 25 deletions
diff --git a/include/linux/tracepoint-defs.h b/include/linux/tracepoint-defs.h index b29950a19205..de97450cf190 100644 --- a/include/linux/tracepoint-defs.h +++ b/include/linux/tracepoint-defs.h @@ -11,6 +11,8 @@ #include <linux/atomic.h> #include <linux/static_key.h> +struct static_call_key; + struct trace_print_flags { unsigned long mask; const char *name; @@ -30,6 +32,9 @@ struct tracepoint_func { struct tracepoint { const char *name; /* Tracepoint name */ struct static_key key; + struct static_call_key *static_call_key; + void *static_call_tramp; + void *iterator; int (*regfunc)(void); void (*unregfunc)(void); struct tracepoint_func __rcu *funcs; diff --git a/include/linux/tracepoint.h b/include/linux/tracepoint.h index 598fec9f9dbf..3722a10fc46d 100644 --- a/include/linux/tracepoint.h +++ b/include/linux/tracepoint.h @@ -19,6 +19,7 @@ #include <linux/cpumask.h> #include <linux/rcupdate.h> #include <linux/tracepoint-defs.h> +#include <linux/static_call.h> struct module; struct tracepoint; @@ -92,7 +93,9 @@ extern int syscall_regfunc(void); extern void syscall_unregfunc(void); #endif /* CONFIG_HAVE_SYSCALL_TRACEPOINTS */ +#ifndef PARAMS #define PARAMS(args...) args +#endif #define TRACE_DEFINE_ENUM(x) #define TRACE_DEFINE_SIZEOF(x) @@ -148,6 +151,12 @@ static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p) #ifdef TRACEPOINTS_ENABLED +#ifdef CONFIG_HAVE_STATIC_CALL +#define __DO_TRACE_CALL(name) static_call(tp_func_##name) +#else +#define __DO_TRACE_CALL(name) __tracepoint_iter_##name +#endif /* CONFIG_HAVE_STATIC_CALL */ + /* * it_func[0] is never NULL because there is at least one element in the array * when the array itself is non NULL. @@ -157,12 +166,11 @@ static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p) * has a "void" prototype, then it is invalid to declare a function * as "(void *, void)". */ -#define __DO_TRACE(tp, proto, args, cond, rcuidle) \ +#define __DO_TRACE(name, proto, args, cond, rcuidle) \ do { \ struct tracepoint_func *it_func_ptr; \ - void *it_func; \ - void *__data; \ int __maybe_unused __idx = 0; \ + void *__data; \ \ if (!(cond)) \ return; \ @@ -182,14 +190,11 @@ static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p) rcu_irq_enter_irqson(); \ } \ \ - it_func_ptr = rcu_dereference_raw((tp)->funcs); \ - \ + it_func_ptr = \ + rcu_dereference_raw((&__tracepoint_##name)->funcs); \ if (it_func_ptr) { \ - do { \ - it_func = (it_func_ptr)->func; \ - __data = (it_func_ptr)->data; \ - ((void(*)(proto))(it_func))(args); \ - } while ((++it_func_ptr)->func); \ + __data = (it_func_ptr)->data; \ + __DO_TRACE_CALL(name)(args); \ } \ \ if (rcuidle) { \ @@ -205,7 +210,7 @@ static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p) static inline void trace_##name##_rcuidle(proto) \ { \ if (static_key_false(&__tracepoint_##name.key)) \ - __DO_TRACE(&__tracepoint_##name, \ + __DO_TRACE(name, \ TP_PROTO(data_proto), \ TP_ARGS(data_args), \ TP_CONDITION(cond), 1); \ @@ -227,11 +232,13 @@ static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p) * poking RCU a bit. */ #define __DECLARE_TRACE(name, proto, args, cond, data_proto, data_args) \ + extern int __tracepoint_iter_##name(data_proto); \ + DECLARE_STATIC_CALL(tp_func_##name, __tracepoint_iter_##name); \ extern struct tracepoint __tracepoint_##name; \ static inline void trace_##name(proto) \ { \ if (static_key_false(&__tracepoint_##name.key)) \ - __DO_TRACE(&__tracepoint_##name, \ + __DO_TRACE(name, \ TP_PROTO(data_proto), \ TP_ARGS(data_args), \ TP_CONDITION(cond), 0); \ @@ -277,21 +284,50 @@ static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p) * structures, so we create an array of pointers that will be used for iteration * on the tracepoints. */ -#define DEFINE_TRACE_FN(name, reg, unreg) \ - static const char __tpstrtab_##name[] \ - __section(__tracepoints_strings) = #name; \ - struct tracepoint __tracepoint_##name __used \ - __section(__tracepoints) = \ - { __tpstrtab_##name, STATIC_KEY_INIT_FALSE, reg, unreg, NULL };\ - __TRACEPOINT_ENTRY(name); +#define DEFINE_TRACE_FN(_name, _reg, _unreg, proto, args) \ + static const char __tpstrtab_##_name[] \ + __section(__tracepoints_strings) = #_name; \ + extern struct static_call_key STATIC_CALL_KEY(tp_func_##_name); \ + int __tracepoint_iter_##_name(void *__data, proto); \ + struct tracepoint __tracepoint_##_name __used \ + __section(__tracepoints) = { \ + .name = __tpstrtab_##_name, \ + .key = STATIC_KEY_INIT_FALSE, \ + .static_call_key = &STATIC_CALL_KEY(tp_func_##_name), \ + .static_call_tramp = STATIC_CALL_TRAMP_ADDR(tp_func_##_name), \ + .iterator = &__tracepoint_iter_##_name, \ + .regfunc = _reg, \ + .unregfunc = _unreg, \ + .funcs = NULL }; \ + __TRACEPOINT_ENTRY(_name); \ + int __tracepoint_iter_##_name(void *__data, proto) \ + { \ + struct tracepoint_func *it_func_ptr; \ + void *it_func; \ + \ + it_func_ptr = \ + rcu_dereference_raw((&__tracepoint_##_name)->funcs); \ + do { \ + it_func = (it_func_ptr)->func; \ + __data = (it_func_ptr)->data; \ + ((void(*)(void *, proto))(it_func))(__data, args); \ + } while ((++it_func_ptr)->func); \ + return 0; \ + } \ + DEFINE_STATIC_CALL(tp_func_##_name, __tracepoint_iter_##_name); -#define DEFINE_TRACE(name) \ - DEFINE_TRACE_FN(name, NULL, NULL); +#define DEFINE_TRACE(name, proto, args) \ + DEFINE_TRACE_FN(name, NULL, NULL, PARAMS(proto), PARAMS(args)); #define EXPORT_TRACEPOINT_SYMBOL_GPL(name) \ - EXPORT_SYMBOL_GPL(__tracepoint_##name) + EXPORT_SYMBOL_GPL(__tracepoint_##name); \ + EXPORT_SYMBOL_GPL(__tracepoint_iter_##name); \ + EXPORT_STATIC_CALL_GPL(tp_func_##name) #define EXPORT_TRACEPOINT_SYMBOL(name) \ - EXPORT_SYMBOL(__tracepoint_##name) + EXPORT_SYMBOL(__tracepoint_##name); \ + EXPORT_SYMBOL(__tracepoint_iter_##name); \ + EXPORT_STATIC_CALL(tp_func_##name) + #else /* !TRACEPOINTS_ENABLED */ #define __DECLARE_TRACE(name, proto, args, cond, data_proto, data_args) \ @@ -320,8 +356,8 @@ static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p) return false; \ } -#define DEFINE_TRACE_FN(name, reg, unreg) -#define DEFINE_TRACE(name) +#define DEFINE_TRACE_FN(name, reg, unreg, proto, args) +#define DEFINE_TRACE(name, proto, args) #define EXPORT_TRACEPOINT_SYMBOL_GPL(name) #define EXPORT_TRACEPOINT_SYMBOL(name) |