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Merge branch 'perf/jump-labels' into perf/core

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Merge reason: After much naming discussion, there seems to be consensus
              now - queue it up for v3.4.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Ingo Molnar
2012-02-28 19:59:45 +01:00
parent 83b8450317 c5905afb0e
commit a706d4fc9e
32 changed files with 589 additions and 207 deletions
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139
include/linux/jump_label.h
View File

@@ -9,15 +9,15 @@
*
* Jump labels provide an interface to generate dynamic branches using
* self-modifying code. Assuming toolchain and architecture support the result
* of a "if (static_branch(&key))" statement is a unconditional branch (which
* of a "if (static_key_false(&key))" statement is a unconditional branch (which
* defaults to false - and the true block is placed out of line).
*
* However at runtime we can change the 'static' branch target using
* jump_label_{inc,dec}(). These function as a 'reference' count on the key
* However at runtime we can change the branch target using
* static_key_slow_{inc,dec}(). These function as a 'reference' count on the key
* object and for as long as there are references all branches referring to
* that particular key will point to the (out of line) true block.
*
* Since this relies on modifying code the jump_label_{inc,dec}() functions
* Since this relies on modifying code the static_key_slow_{inc,dec}() functions
* must be considered absolute slow paths (machine wide synchronization etc.).
* OTOH, since the affected branches are unconditional their runtime overhead
* will be absolutely minimal, esp. in the default (off) case where the total
@@ -26,12 +26,26 @@
*
* When the control is directly exposed to userspace it is prudent to delay the
* decrement to avoid high frequency code modifications which can (and do)
* cause significant performance degradation. Struct jump_label_key_deferred and
* jump_label_dec_deferred() provide for this.
* cause significant performance degradation. Struct static_key_deferred and
* static_key_slow_dec_deferred() provide for this.
*
* Lacking toolchain and or architecture support, it falls back to a simple
* conditional branch.
*/
*
* struct static_key my_key = STATIC_KEY_INIT_TRUE;
*
* if (static_key_true(&my_key)) {
* }
*
* will result in the true case being in-line and starts the key with a single
* reference. Mixing static_key_true() and static_key_false() on the same key is not
* allowed.
*
* Not initializing the key (static data is initialized to 0s anyway) is the
* same as using STATIC_KEY_INIT_FALSE and static_key_false() is
* equivalent with static_branch().
*
*/
#include <linux/types.h>
#include <linux/compiler.h>
@@ -39,16 +53,17 @@
#if defined(CC_HAVE_ASM_GOTO) && defined(CONFIG_JUMP_LABEL)
struct jump_label_key {
struct static_key {
atomic_t enabled;
/* Set lsb bit to 1 if branch is default true, 0 ot */
struct jump_entry *entries;
#ifdef CONFIG_MODULES
struct jump_label_mod *next;
struct static_key_mod *next;
#endif
};
struct jump_label_key_deferred {
struct jump_label_key key;
struct static_key_deferred {
struct static_key key;
unsigned long timeout;
struct delayed_work work;
};
@@ -66,13 +81,34 @@ struct module;
#ifdef HAVE_JUMP_LABEL
#ifdef CONFIG_MODULES
#define JUMP_LABEL_INIT {ATOMIC_INIT(0), NULL, NULL}
#else
#define JUMP_LABEL_INIT {ATOMIC_INIT(0), NULL}
#endif
#define JUMP_LABEL_TRUE_BRANCH 1UL
static __always_inline bool static_branch(struct jump_label_key *key)
static
inline struct jump_entry *jump_label_get_entries(struct static_key *key)
{
return (struct jump_entry *)((unsigned long)key->entries
& ~JUMP_LABEL_TRUE_BRANCH);
}
static inline bool jump_label_get_branch_default(struct static_key *key)
{
if ((unsigned long)key->entries & JUMP_LABEL_TRUE_BRANCH)
return true;
return false;
}
static __always_inline bool static_key_false(struct static_key *key)
{
return arch_static_branch(key);
}
static __always_inline bool static_key_true(struct static_key *key)
{
return !static_key_false(key);
}
/* Deprecated. Please use 'static_key_false() instead. */
static __always_inline bool static_branch(struct static_key *key)
{
return arch_static_branch(key);
}
@@ -88,21 +124,24 @@ extern void arch_jump_label_transform(struct jump_entry *entry,
extern void arch_jump_label_transform_static(struct jump_entry *entry,
enum jump_label_type type);
extern int jump_label_text_reserved(void *start, void *end);
extern void jump_label_inc(struct jump_label_key *key);
extern void jump_label_dec(struct jump_label_key *key);
extern void jump_label_dec_deferred(struct jump_label_key_deferred *key);
extern bool jump_label_enabled(struct jump_label_key *key);
extern void static_key_slow_inc(struct static_key *key);
extern void static_key_slow_dec(struct static_key *key);
extern void static_key_slow_dec_deferred(struct static_key_deferred *key);
extern bool static_key_enabled(struct static_key *key);
extern void jump_label_apply_nops(struct module *mod);
extern void jump_label_rate_limit(struct jump_label_key_deferred *key,
unsigned long rl);
extern void
jump_label_rate_limit(struct static_key_deferred *key, unsigned long rl);
#define STATIC_KEY_INIT_TRUE ((struct static_key) \
{ .enabled = ATOMIC_INIT(1), .entries = (void *)1 })
#define STATIC_KEY_INIT_FALSE ((struct static_key) \
{ .enabled = ATOMIC_INIT(0), .entries = (void *)0 })
#else /* !HAVE_JUMP_LABEL */
#include <linux/atomic.h>
#define JUMP_LABEL_INIT {ATOMIC_INIT(0)}
struct jump_label_key {
struct static_key {
atomic_t enabled;
};
@@ -110,30 +149,45 @@ static __always_inline void jump_label_init(void)
{
}
struct jump_label_key_deferred {
struct jump_label_key key;
struct static_key_deferred {
struct static_key key;
};
static __always_inline bool static_branch(struct jump_label_key *key)
static __always_inline bool static_key_false(struct static_key *key)
{
if (unlikely(atomic_read(&key->enabled)))
if (unlikely(atomic_read(&key->enabled)) > 0)
return true;
return false;
}
static inline void jump_label_inc(struct jump_label_key *key)
static __always_inline bool static_key_true(struct static_key *key)
{
if (likely(atomic_read(&key->enabled)) > 0)
return true;
return false;
}
/* Deprecated. Please use 'static_key_false() instead. */
static __always_inline bool static_branch(struct static_key *key)
{
if (unlikely(atomic_read(&key->enabled)) > 0)
return true;
return false;
}
static inline void static_key_slow_inc(struct static_key *key)
{
atomic_inc(&key->enabled);
}
static inline void jump_label_dec(struct jump_label_key *key)
static inline void static_key_slow_dec(struct static_key *key)
{
atomic_dec(&key->enabled);
}
static inline void jump_label_dec_deferred(struct jump_label_key_deferred *key)
static inline void static_key_slow_dec_deferred(struct static_key_deferred *key)
{
jump_label_dec(&key->key);
static_key_slow_dec(&key->key);
}
static inline int jump_label_text_reserved(void *start, void *end)
@@ -144,9 +198,9 @@ static inline int jump_label_text_reserved(void *start, void *end)
static inline void jump_label_lock(void) {}
static inline void jump_label_unlock(void) {}
static inline bool jump_label_enabled(struct jump_label_key *key)
static inline bool static_key_enabled(struct static_key *key)
{
return !!atomic_read(&key->enabled);
return (atomic_read(&key->enabled) > 0);
}
static inline int jump_label_apply_nops(struct module *mod)
@@ -154,13 +208,20 @@ static inline int jump_label_apply_nops(struct module *mod)
return 0;
}
static inline void jump_label_rate_limit(struct jump_label_key_deferred *key,
static inline void
jump_label_rate_limit(struct static_key_deferred *key,
unsigned long rl)
{
}
#define STATIC_KEY_INIT_TRUE ((struct static_key) \
{ .enabled = ATOMIC_INIT(1) })
#define STATIC_KEY_INIT_FALSE ((struct static_key) \
{ .enabled = ATOMIC_INIT(0) })
#endif /* HAVE_JUMP_LABEL */
#define jump_label_key_enabled ((struct jump_label_key){ .enabled = ATOMIC_INIT(1), })
#define jump_label_key_disabled ((struct jump_label_key){ .enabled = ATOMIC_INIT(0), })
#define STATIC_KEY_INIT STATIC_KEY_INIT_FALSE
#define jump_label_enabled static_key_enabled
#endif /* _LINUX_JUMP_LABEL_H */

4
include/linux/netdevice.h
View File

@@ -214,8 +214,8 @@ enum {
#include <linux/skbuff.h>
#ifdef CONFIG_RPS
#include <linux/jump_label.h>
extern struct jump_label_key rps_needed;
#include <linux/static_key.h>
extern struct static_key rps_needed;
#endif
struct neighbour;

6
include/linux/netfilter.h
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@@ -163,13 +163,13 @@ extern struct ctl_path nf_net_ipv4_netfilter_sysctl_path[];
extern struct list_head nf_hooks[NFPROTO_NUMPROTO][NF_MAX_HOOKS];
#if defined(CONFIG_JUMP_LABEL)
#include <linux/jump_label.h>
extern struct jump_label_key nf_hooks_needed[NFPROTO_NUMPROTO][NF_MAX_HOOKS];
#include <linux/static_key.h>
extern struct static_key nf_hooks_needed[NFPROTO_NUMPROTO][NF_MAX_HOOKS];
static inline bool nf_hooks_active(u_int8_t pf, unsigned int hook)
{
if (__builtin_constant_p(pf) &&
__builtin_constant_p(hook))
return static_branch(&nf_hooks_needed[pf][hook]);
return static_key_false(&nf_hooks_needed[pf][hook]);
return !list_empty(&nf_hooks[pf][hook]);
}

12
include/linux/perf_event.h
View File

@@ -514,7 +514,7 @@ struct perf_guest_info_callbacks {
#include <linux/ftrace.h>
#include <linux/cpu.h>
#include <linux/irq_work.h>
#include <linux/jump_label.h>
#include <linux/static_key.h>
#include <linux/atomic.h>
#include <asm/local.h>
@@ -1041,7 +1041,7 @@ static inline int is_software_event(struct perf_event *event)
return event->pmu->task_ctx_nr == perf_sw_context;
}
extern struct jump_label_key perf_swevent_enabled[PERF_COUNT_SW_MAX];
extern struct static_key perf_swevent_enabled[PERF_COUNT_SW_MAX];
extern void __perf_sw_event(u32, u64, struct pt_regs *, u64);
@@ -1069,7 +1069,7 @@ perf_sw_event(u32 event_id, u64 nr, struct pt_regs *regs, u64 addr)
{
struct pt_regs hot_regs;
if (static_branch(&perf_swevent_enabled[event_id])) {
if (static_key_false(&perf_swevent_enabled[event_id])) {
if (!regs) {
perf_fetch_caller_regs(&hot_regs);
regs = &hot_regs;
@@ -1078,12 +1078,12 @@ perf_sw_event(u32 event_id, u64 nr, struct pt_regs *regs, u64 addr)
}
}
extern struct jump_label_key_deferred perf_sched_events;
extern struct static_key_deferred perf_sched_events;
static inline void perf_event_task_sched_in(struct task_struct *prev,
struct task_struct *task)
{
if (static_branch(&perf_sched_events.key))
if (static_key_false(&perf_sched_events.key))
__perf_event_task_sched_in(prev, task);
}
@@ -1092,7 +1092,7 @@ static inline void perf_event_task_sched_out(struct task_struct *prev,
{
perf_sw_event(PERF_COUNT_SW_CONTEXT_SWITCHES, 1, NULL, 0);
if (static_branch(&perf_sched_events.key))
if (static_key_false(&perf_sched_events.key))
__perf_event_task_sched_out(prev, next);
}

1
include/linux/static_key.h Normal file
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@@ -0,0 +1 @@
#include <linux/jump_label.h>

8
include/linux/tracepoint.h
View File

@@ -17,7 +17,7 @@
#include <linux/errno.h>
#include <linux/types.h>
#include <linux/rcupdate.h>
#include <linux/jump_label.h>
#include <linux/static_key.h>
struct module;
struct tracepoint;
@@ -29,7 +29,7 @@ struct tracepoint_func {
struct tracepoint {
const char *name; /* Tracepoint name */
struct jump_label_key key;
struct static_key key;
void (*regfunc)(void);
void (*unregfunc)(void);
struct tracepoint_func __rcu *funcs;
@@ -145,7 +145,7 @@ static inline void tracepoint_synchronize_unregister(void)
extern struct tracepoint __tracepoint_##name; \
static inline void trace_##name(proto) \
{ \
if (static_branch(&__tracepoint_##name.key)) \
if (static_key_false(&__tracepoint_##name.key)) \
__DO_TRACE(&__tracepoint_##name, \
TP_PROTO(data_proto), \
TP_ARGS(data_args), \
@@ -188,7 +188,7 @@ static inline void tracepoint_synchronize_unregister(void)
__attribute__((section("__tracepoints_strings"))) = #name; \
struct tracepoint __tracepoint_##name \
__attribute__((section("__tracepoints"))) = \
{ __tpstrtab_##name, JUMP_LABEL_INIT, reg, unreg, NULL };\
{ __tpstrtab_##name, STATIC_KEY_INIT_FALSE, reg, unreg, NULL };\
static struct tracepoint * const __tracepoint_ptr_##name __used \
__attribute__((section("__tracepoints_ptrs"))) = \
&__tracepoint_##name;