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tracepoint: Optimize using static_call()

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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
This commit is contained in:
Steven Rostedt (VMware)
2020-08-18 15:57:52 +02:00
committed by Ingo Molnar
parent a945c8345e
commit d25e37d89d
4 changed files with 94 additions and 36 deletions
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5
include/linux/tracepoint-defs.h
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@@ -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;