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MDEV-14529 - InnoDB rw-locks: optimize memory barriers
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Change lock_word from lint to int32_t: the latter is my_atomic_* friendly type.
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@svoj
svoj committed Dec 8, 2017
1 parent db715ff commit c73e77d
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Showing 5 changed files with 29 additions and 34 deletions.
6 changes: 3 additions & 3 deletions storage/innobase/include/sync0rw.h
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Original file line number Diff line number Diff line change
Expand Up @@ -501,8 +501,8 @@ bool
rw_lock_lock_word_decr(
/*===================*/
rw_lock_t* lock, /*!< in/out: rw-lock */
ulint amount, /*!< in: amount to decrement */
lint threshold); /*!< in: threshold of judgement */
int32_t amount, /*!< in: amount to decrement */
int32_t threshold); /*!< in: threshold of judgement */
#ifdef UNIV_DEBUG
/******************************************************************//**
Checks if the thread has locked the rw-lock in the specified mode, with
Expand Down Expand Up @@ -571,7 +571,7 @@ struct rw_lock_t
#endif /* UNIV_DEBUG */
{
/** Holds the state of the lock. */
volatile lint lock_word;
volatile int32_t lock_word;

/** 1: there are waiters */
volatile uint32_t waiters;
Expand Down
41 changes: 20 additions & 21 deletions storage/innobase/include/sync0rw.ic
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Original file line number Diff line number Diff line change
Expand Up @@ -77,7 +77,7 @@ rw_lock_get_writer(
/*===============*/
const rw_lock_t* lock) /*!< in: rw-lock */
{
lint lock_word = lock->lock_word;
int32_t lock_word = lock->lock_word;

ut_ad(lock_word <= X_LOCK_DECR);
if (lock_word > X_LOCK_HALF_DECR) {
Expand Down Expand Up @@ -109,7 +109,7 @@ rw_lock_get_reader_count(
/*=====================*/
const rw_lock_t* lock) /*!< in: rw-lock */
{
lint lock_word = lock->lock_word;
int32_t lock_word = lock->lock_word;
ut_ad(lock_word <= X_LOCK_DECR);

if (lock_word > X_LOCK_HALF_DECR) {
Expand Down Expand Up @@ -145,7 +145,7 @@ rw_lock_get_x_lock_count(
/*=====================*/
const rw_lock_t* lock) /*!< in: rw-lock */
{
lint lock_copy = lock->lock_word;
int32_t lock_copy = lock->lock_word;
ut_ad(lock_copy <= X_LOCK_DECR);

if (lock_copy == 0 || lock_copy == -X_LOCK_HALF_DECR) {
Expand Down Expand Up @@ -178,7 +178,7 @@ rw_lock_get_sx_lock_count(
const rw_lock_t* lock) /*!< in: rw-lock */
{
#ifdef UNIV_DEBUG
lint lock_copy = lock->lock_word;
int32_t lock_copy = lock->lock_word;

ut_ad(lock_copy <= X_LOCK_DECR);

Expand Down Expand Up @@ -208,17 +208,16 @@ bool
rw_lock_lock_word_decr(
/*===================*/
rw_lock_t* lock, /*!< in/out: rw-lock */
ulint amount, /*!< in: amount to decrement */
lint threshold) /*!< in: threshold of judgement */
int32_t amount, /*!< in: amount to decrement */
int32_t threshold) /*!< in: threshold of judgement */
{
lint local_lock_word;
int32_t local_lock_word;

local_lock_word = my_atomic_loadlint_explicit(&lock->lock_word,
MY_MEMORY_ORDER_RELAXED);
local_lock_word = my_atomic_load32_explicit(&lock->lock_word,
MY_MEMORY_ORDER_RELAXED);
while (local_lock_word > threshold) {
if (my_atomic_caslint(&lock->lock_word,
&local_lock_word,
local_lock_word - amount)) {
if (my_atomic_cas32(&lock->lock_word, &local_lock_word,
local_lock_word - amount)) {
return(true);
}
}
Expand Down Expand Up @@ -306,9 +305,9 @@ rw_lock_x_lock_func_nowait(
const char* file_name,/*!< in: file name where lock requested */
unsigned line) /*!< in: line where requested */
{
lint oldval = X_LOCK_DECR;
int32_t oldval = X_LOCK_DECR;

if (my_atomic_caslint(&lock->lock_word, &oldval, 0)) {
if (my_atomic_cas32(&lock->lock_word, &oldval, 0)) {
lock->writer_thread = os_thread_get_curr_id();

} else if (os_thread_eq(lock->writer_thread, os_thread_get_curr_id())) {
Expand Down Expand Up @@ -357,7 +356,7 @@ rw_lock_s_unlock_func(
rw_lock_t* lock) /*!< in/out: rw-lock */
{
#ifdef UNIV_DEBUG
lint dbg_lock_word = my_atomic_loadlint_explicit(
int32_t dbg_lock_word = my_atomic_load32_explicit(
&lock->lock_word, MY_MEMORY_ORDER_RELAXED);
ut_ad(dbg_lock_word > -X_LOCK_DECR);
ut_ad(dbg_lock_word != 0);
Expand All @@ -367,7 +366,7 @@ rw_lock_s_unlock_func(
ut_d(rw_lock_remove_debug_info(lock, pass, RW_LOCK_S));

/* Increment lock_word to indicate 1 less reader */
lint lock_word = my_atomic_addlint(&lock->lock_word, 1) + 1;
int32_t lock_word = my_atomic_add32(&lock->lock_word, 1) + 1;
if (lock_word == 0 || lock_word == -X_LOCK_HALF_DECR) {

/* wait_ex waiter exists. It may not be asleep, but we signal
Expand All @@ -393,9 +392,9 @@ rw_lock_x_unlock_func(
#endif /* UNIV_DEBUG */
rw_lock_t* lock) /*!< in/out: rw-lock */
{
lint lock_word;
lock_word = my_atomic_loadlint_explicit(&lock->lock_word,
MY_MEMORY_ORDER_RELAXED);
int32_t lock_word;
lock_word = my_atomic_load32_explicit(&lock->lock_word,
MY_MEMORY_ORDER_RELAXED);

ut_ad(lock_word == 0 || lock_word == -X_LOCK_HALF_DECR
|| lock_word <= -X_LOCK_DECR);
Expand All @@ -410,7 +409,7 @@ rw_lock_x_unlock_func(
if (lock_word == 0 || lock_word == -X_LOCK_HALF_DECR) {
/* There is 1 x-lock */
/* atomic increment is needed, because it is last */
if (my_atomic_addlint(&lock->lock_word, X_LOCK_DECR) <= -X_LOCK_DECR) {
if (my_atomic_add32(&lock->lock_word, X_LOCK_DECR) <= -X_LOCK_DECR) {
ut_error;
}

Expand Down Expand Up @@ -462,7 +461,7 @@ rw_lock_sx_unlock_func(
if (lock->lock_word > 0) {
lock->writer_thread = 0;

if (my_atomic_addlint(&lock->lock_word, X_LOCK_HALF_DECR) <= 0) {
if (my_atomic_add32(&lock->lock_word, X_LOCK_HALF_DECR) <= 0) {
ut_error;
}
/* Lock is now free. May have to signal read/write
Expand Down
4 changes: 0 additions & 4 deletions storage/innobase/include/sync0types.h
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Original file line number Diff line number Diff line change
Expand Up @@ -1163,15 +1163,11 @@ enum rw_lock_flag_t {
#ifdef _WIN64
#define my_atomic_addlint(A,B) my_atomic_add64((int64*) (A), (B))
#define my_atomic_loadlint(A) my_atomic_load64((int64*) (A))
#define my_atomic_loadlint_explicit(A,O) my_atomic_load64_explicit((int64*) (A), (O))
#define my_atomic_storelint(A,B) my_atomic_store64((int64*) (A), (B))
#define my_atomic_caslint(A,B,C) my_atomic_cas64((int64*) (A), (int64*) (B), (C))
#else
#define my_atomic_addlint my_atomic_addlong
#define my_atomic_loadlint my_atomic_loadlong
#define my_atomic_loadlint_explicit my_atomic_loadlong_explicit
#define my_atomic_storelint my_atomic_storelong
#define my_atomic_caslint my_atomic_caslong
#endif

/** Simple counter aligned to CACHE_LINE_SIZE
Expand Down
2 changes: 1 addition & 1 deletion storage/innobase/sync/sync0arr.cc
View file
Original file line number Diff line number Diff line change
Expand Up @@ -589,7 +589,7 @@ sync_array_cell_print(
fprintf(file,
"number of readers " ULINTPF
", waiters flag %u, "
"lock_word: " ULINTPFx "\n"
"lock_word: %x\n"
"Last time read locked in file %s line %u\n"
"Last time write locked in file %s line %u"
#if 0 /* JAN: TODO: FIX LATER */
Expand Down
10 changes: 5 additions & 5 deletions storage/innobase/sync/sync0rw.cc
View file
Original file line number Diff line number Diff line change
Expand Up @@ -316,8 +316,8 @@ rw_lock_s_lock_spin(
/* Spin waiting for the writer field to become free */
HMT_low();
while (i < srv_n_spin_wait_rounds &&
my_atomic_loadlint_explicit(&lock->lock_word,
MY_MEMORY_ORDER_RELAXED) <= 0) {
my_atomic_load32_explicit(&lock->lock_word,
MY_MEMORY_ORDER_RELAXED) <= 0) {
if (srv_spin_wait_delay) {
ut_delay(ut_rnd_interval(0, srv_spin_wait_delay));
}
Expand Down Expand Up @@ -883,12 +883,12 @@ rw_lock_validate(
/*=============*/
const rw_lock_t* lock) /*!< in: rw-lock */
{
lint lock_word;
int32_t lock_word;

ut_ad(lock);

lock_word = my_atomic_loadlint_explicit(&lock->lock_word,
MY_MEMORY_ORDER_RELAXED);
lock_word = my_atomic_load32_explicit(const_cast<int32_t*>(&lock->lock_word),
MY_MEMORY_ORDER_RELAXED);

ut_ad(lock->magic_n == RW_LOCK_MAGIC_N);
ut_ad(my_atomic_load32_explicit((int32*) &lock->waiters,
Expand Down

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