MEDIUM: threads: keep history of taken locks with DEBUG_THREAD > 0
by only storing a word in each thread context, we can keep the history of all taken/dropped locks by label. This is expected to be very cheap and to permit to store up to 8 consecutive lock operations in 64 bits. That should significantly help detect recursive locks as well as figure what thread was likely to hinder another one waiting for a lock. For now we only store the final state of the lock, we don't store the attempt to get it. It's just a matter of space since we already need 4 ops (rd,sk,wr,un) which take 2 bits, leaving max 64 labels. We're already around 45. We could also multiply by 5 and still keep 8 bits total per lock, that would limit us to 51 locks max. It seems that most of the time if we get a watchdog panic, anyway the victim thread will be perfectly located so that we don't need a specific value for this. Another benefit is that we perform a single memory write per lock.
This commit is contained in:
Willy Tarreau
parent
23371b3e7c
commit
b8a1c2380b
@ -305,35 +305,61 @@ static inline unsigned long thread_isolated()
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return _HA_ATOMIC_LOAD(&isolated_thread) == tid;
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}
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/* locking levels, for history and debugging */
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#define _LK_UN 0
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#define _LK_RD 1
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#define _LK_SK 2
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#define _LK_WR 3
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#if (DEBUG_THREAD < 1) && !defined(DEBUG_FULL)
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#define _lock_wait(_LK_, lbl, expr) do { (void)(expr); } while (0)
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#define _lock_cond(_LK_, lbl, expr) ({ typeof(expr) _expr = (expr); _expr; })
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#else
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#define _lock_wait(_LK_, lbl, expr) do { \
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(void)(expr); \
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th_ctx->lock_history = (th_ctx->lock_history << 8) + ((lbl + 1) << 2) + _LK_; \
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} while (0)
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#define _lock_cond(_LK_, lbl, expr) ({ \
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typeof(expr) _expr = (expr); \
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if (!_expr) \
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th_ctx->lock_history = (th_ctx->lock_history << 8) + ((lbl + 1) << 2) + _LK_; \
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_expr; \
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})
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#endif
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#if (DEBUG_THREAD < 2) && !defined(DEBUG_FULL)
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/* Thread debugging is DISABLED, these are the regular locking functions */
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#define HA_SPIN_INIT(l) ({ (*l) = 0; })
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#define HA_SPIN_DESTROY(l) ({ (*l) = 0; })
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#define HA_SPIN_LOCK(lbl, l) pl_take_s(l)
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#define HA_SPIN_TRYLOCK(lbl, l) (!pl_try_s(l))
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#define HA_SPIN_UNLOCK(lbl, l) pl_drop_s(l)
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#define HA_SPIN_LOCK(lbl, l) _lock_wait(_LK_SK, lbl, pl_take_s(l))
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#define HA_SPIN_TRYLOCK(lbl, l) _lock_cond(_LK_SK, lbl, !pl_try_s(l))
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#define HA_SPIN_UNLOCK(lbl, l) _lock_wait(_LK_UN, lbl, pl_drop_s(l))
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#define HA_RWLOCK_INIT(l) ({ (*l) = 0; })
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#define HA_RWLOCK_DESTROY(l) ({ (*l) = 0; })
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#define HA_RWLOCK_WRLOCK(lbl,l) pl_take_w(l)
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#define HA_RWLOCK_TRYWRLOCK(lbl,l) (!pl_try_w(l))
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#define HA_RWLOCK_WRUNLOCK(lbl,l) pl_drop_w(l)
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#define HA_RWLOCK_RDLOCK(lbl,l) pl_take_r(l)
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#define HA_RWLOCK_TRYRDLOCK(lbl,l) (!pl_try_r(l))
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#define HA_RWLOCK_RDUNLOCK(lbl,l) pl_drop_r(l)
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#define HA_RWLOCK_WRLOCK(lbl,l) _lock_wait(_LK_WR, lbl, pl_take_w(l))
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#define HA_RWLOCK_TRYWRLOCK(lbl,l) _lock_cond(_LK_WR, lbl, !pl_try_w(l))
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#define HA_RWLOCK_WRUNLOCK(lbl,l) _lock_wait(_LK_UN, lbl, pl_drop_w(l))
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#define HA_RWLOCK_RDLOCK(lbl,l) _lock_wait(_LK_RD, lbl, pl_take_r(l))
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#define HA_RWLOCK_TRYRDLOCK(lbl,l) _lock_cond(_LK_RD, lbl, (!pl_try_r(l)))
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#define HA_RWLOCK_RDUNLOCK(lbl,l) _lock_wait(_LK_UN, lbl, pl_drop_r(l))
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/* rwlock upgrades via seek locks */
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#define HA_RWLOCK_SKLOCK(lbl,l) pl_take_s(l) /* N --> S */
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#define HA_RWLOCK_SKTOWR(lbl,l) pl_stow(l) /* S --> W */
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#define HA_RWLOCK_WRTOSK(lbl,l) pl_wtos(l) /* W --> S */
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#define HA_RWLOCK_SKTORD(lbl,l) pl_stor(l) /* S --> R */
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#define HA_RWLOCK_WRTORD(lbl,l) pl_wtor(l) /* W --> R */
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#define HA_RWLOCK_SKUNLOCK(lbl,l) pl_drop_s(l) /* S --> N */
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#define HA_RWLOCK_TRYSKLOCK(lbl,l) (!pl_try_s(l)) /* N -?> S */
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#define HA_RWLOCK_TRYRDTOSK(lbl,l) (!pl_try_rtos(l)) /* R -?> S */
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#define HA_RWLOCK_TRYRDTOWR(lbl, l) (!pl_try_rtow(l)) /* R -?> W */
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#define HA_RWLOCK_SKLOCK(lbl,l) _lock_wait(_LK_SK, lbl, pl_take_s(l)) /* N --> S */
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#define HA_RWLOCK_SKTOWR(lbl,l) _lock_wait(_LK_WR, lbl, pl_stow(l)) /* S --> W */
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#define HA_RWLOCK_WRTOSK(lbl,l) _lock_wait(_LK_SK, lbl, pl_wtos(l)) /* W --> S */
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#define HA_RWLOCK_SKTORD(lbl,l) _lock_wait(_LK_RD, lbl, pl_stor(l)) /* S --> R */
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#define HA_RWLOCK_WRTORD(lbl,l) _lock_wait(_LK_RD, lbl, pl_wtor(l)) /* W --> R */
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#define HA_RWLOCK_SKUNLOCK(lbl,l) _lock_wait(_LK_UN, lbl, pl_drop_s(l)) /* S --> N */
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#define HA_RWLOCK_TRYSKLOCK(lbl,l) _lock_cond(_LK_SK, lbl, !pl_try_s(l)) /* N -?> S */
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#define HA_RWLOCK_TRYRDTOSK(lbl,l) _lock_cond(_LK_SK, lbl, !pl_try_rtos(l)) /* R -?> S */
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#define HA_RWLOCK_TRYRDTOWR(lbl, l) _lock_cond(_LK_WR, lbl, !pl_try_rtow(l)) /* R -?> W */
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#else /* (DEBUG_THREAD < 2) && !defined(DEBUG_FULL) */
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@ -368,28 +394,28 @@ static inline unsigned long thread_isolated()
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#define HA_SPIN_INIT(l) __spin_init(l)
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#define HA_SPIN_DESTROY(l) __spin_destroy(l)
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#define HA_SPIN_LOCK(lbl, l) __spin_lock(lbl, l, __func__, __FILE__, __LINE__)
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#define HA_SPIN_TRYLOCK(lbl, l) __spin_trylock(lbl, l, __func__, __FILE__, __LINE__)
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#define HA_SPIN_UNLOCK(lbl, l) __spin_unlock(lbl, l, __func__, __FILE__, __LINE__)
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#define HA_SPIN_LOCK(lbl, l) _lock_wait(_LK_SK, lbl, __spin_lock(lbl, l, __func__, __FILE__, __LINE__))
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#define HA_SPIN_TRYLOCK(lbl, l) _lock_cond(_LK_SK, lbl, __spin_trylock(lbl, l, __func__, __FILE__, __LINE__))
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#define HA_SPIN_UNLOCK(lbl, l) _lock_wait(_LK_UN, lbl, __spin_unlock(lbl, l, __func__, __FILE__, __LINE__))
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#define HA_RWLOCK_INIT(l) __ha_rwlock_init((l))
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#define HA_RWLOCK_DESTROY(l) __ha_rwlock_destroy((l))
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#define HA_RWLOCK_WRLOCK(lbl,l) __ha_rwlock_wrlock(lbl, l, __func__, __FILE__, __LINE__)
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#define HA_RWLOCK_TRYWRLOCK(lbl,l) __ha_rwlock_trywrlock(lbl, l, __func__, __FILE__, __LINE__)
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#define HA_RWLOCK_WRUNLOCK(lbl,l) __ha_rwlock_wrunlock(lbl, l, __func__, __FILE__, __LINE__)
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#define HA_RWLOCK_RDLOCK(lbl,l) __ha_rwlock_rdlock(lbl, l)
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#define HA_RWLOCK_TRYRDLOCK(lbl,l) __ha_rwlock_tryrdlock(lbl, l)
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#define HA_RWLOCK_RDUNLOCK(lbl,l) __ha_rwlock_rdunlock(lbl, l)
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#define HA_RWLOCK_WRLOCK(lbl,l) _lock_wait(_LK_WR, lbl, __ha_rwlock_wrlock(lbl, l, __func__, __FILE__, __LINE__))
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#define HA_RWLOCK_TRYWRLOCK(lbl,l) _lock_cond(_LK_WR, lbl, __ha_rwlock_trywrlock(lbl, l, __func__, __FILE__, __LINE__))
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#define HA_RWLOCK_WRUNLOCK(lbl,l) _lock_wait(_LK_UN, lbl, __ha_rwlock_wrunlock(lbl, l, __func__, __FILE__, __LINE__))
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#define HA_RWLOCK_RDLOCK(lbl,l) _lock_wait(_LK_RD, lbl, __ha_rwlock_rdlock(lbl, l))
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#define HA_RWLOCK_TRYRDLOCK(lbl,l) _lock_cond(_LK_RD, lbl, __ha_rwlock_tryrdlock(lbl, l))
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#define HA_RWLOCK_RDUNLOCK(lbl,l) _lock_wait(_LK_UN, lbl, __ha_rwlock_rdunlock(lbl, l))
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#define HA_RWLOCK_SKLOCK(lbl,l) __ha_rwlock_sklock(lbl, l, __func__, __FILE__, __LINE__)
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#define HA_RWLOCK_SKTOWR(lbl,l) __ha_rwlock_sktowr(lbl, l, __func__, __FILE__, __LINE__)
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#define HA_RWLOCK_WRTOSK(lbl,l) __ha_rwlock_wrtosk(lbl, l, __func__, __FILE__, __LINE__)
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#define HA_RWLOCK_SKTORD(lbl,l) __ha_rwlock_sktord(lbl, l, __func__, __FILE__, __LINE__)
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#define HA_RWLOCK_WRTORD(lbl,l) __ha_rwlock_wrtord(lbl, l, __func__, __FILE__, __LINE__)
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#define HA_RWLOCK_SKUNLOCK(lbl,l) __ha_rwlock_skunlock(lbl, l, __func__, __FILE__, __LINE__)
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#define HA_RWLOCK_TRYSKLOCK(lbl,l) __ha_rwlock_trysklock(lbl, l, __func__, __FILE__, __LINE__)
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#define HA_RWLOCK_TRYRDTOSK(lbl,l) __ha_rwlock_tryrdtosk(lbl, l, __func__, __FILE__, __LINE__)
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#define HA_RWLOCK_TRYRDTOWR(lbl,l) __ha_rwlock_tryrdtowr(lbl, l, __func__, __FILE__, __LINE__)
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#define HA_RWLOCK_SKLOCK(lbl,l) _lock_wait(_LK_SK, lbl, __ha_rwlock_sklock(lbl, l, __func__, __FILE__, __LINE__))
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#define HA_RWLOCK_SKTOWR(lbl,l) _lock_wait(_LK_WR, lbl, __ha_rwlock_sktowr(lbl, l, __func__, __FILE__, __LINE__))
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#define HA_RWLOCK_WRTOSK(lbl,l) _lock_wait(_LK_SK, lbl, __ha_rwlock_wrtosk(lbl, l, __func__, __FILE__, __LINE__))
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#define HA_RWLOCK_SKTORD(lbl,l) _lock_wait(_LK_RD, lbl, __ha_rwlock_sktord(lbl, l, __func__, __FILE__, __LINE__))
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#define HA_RWLOCK_WRTORD(lbl,l) _lock_wait(_LK_RD, lbl, __ha_rwlock_wrtord(lbl, l, __func__, __FILE__, __LINE__))
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#define HA_RWLOCK_SKUNLOCK(lbl,l) _lock_wait(_LK_UN, lbl, __ha_rwlock_skunlock(lbl, l, __func__, __FILE__, __LINE__))
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#define HA_RWLOCK_TRYSKLOCK(lbl,l) _lock_cond(_LK_SK, lbl, __ha_rwlock_trysklock(lbl, l, __func__, __FILE__, __LINE__))
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#define HA_RWLOCK_TRYRDTOSK(lbl,l) _lock_cond(_LK_RD, lbl, __ha_rwlock_tryrdtosk(lbl, l, __func__, __FILE__, __LINE__))
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#define HA_RWLOCK_TRYRDTOWR(lbl,l) _lock_cond(_LK_WR, lbl, __ha_rwlock_tryrdtowr(lbl, l, __func__, __FILE__, __LINE__))
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/* Following functions are used to collect some stats about locks. We wrap
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* pthread functions to known how much time we wait in a lock. */
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@ -165,7 +165,7 @@ struct thread_ctx {
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uint64_t prev_mono_time; /* previous system wide monotonic time (leaving poll) */
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uint64_t curr_mono_time; /* latest system wide monotonic time (leaving poll) */
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// around 8 bytes here for thread-local variables
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ulong lock_history; /* history of used locks, see thread.h for more details */
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// third cache line here on 64 bits: accessed mostly using atomic ops
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ALWAYS_ALIGN(64);
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