[PATCH v3] linux-gen: timer: enhance timer expire scalability #1871
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platform/linux-generic/odp_timer.c
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| uintptr_t slot_addr; | ||
| int slot_index = (tick / tp->param.res_ns) % MAX_SLOT_NUM; | ||
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| odp_spinlock_lock(&tp->timing_wheel.lock_pool[slot_index]); |
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To avoid locking on every scan call, could timer expiration first checked with relaxed reads and only when a thread finds expired timer, it would lock (or use atomics) to remove the expired timer from the data structure. Relaxed checking needs that expiration times are saved into a data structure that does not break, if another thread cancels/expires a timer simultaneuosly.
Use stash and pre-allocated memory to store tick_buf index, so timer_expire can find expire tick_buf index with hash function without walk through all tick_buf. Additional overhead is introduced to start and cancel operation. Expire operation cycle cost is constant with more timers. Timer set and cancel operation cycles Base 69 Current 139 Expire operation cycles Timer num. 10 100 1000 Base 37 38 190 Current 40 39 37 Signed-off-by: Tianyu Li <tianyu.li@arm.com>
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Use stash and pre-allocated memory to store tick_buf index, so timer_expire can find expire tick_buf index with hash function without walk through all tick_buf.
Addtional overhead introduced to timer start and cancel operation. Expire operation cost remain constant.
Timer set and cancel operation cycles
Base 69
Current 139
Expire operation cycles
Timer num. 10 100 1000
Base 37 38 190
Current 40 39 37