chenBright commented on code in PR #3009: URL: https://github.com/apache/brpc/pull/3009#discussion_r2173632622
########## src/bthread/task_control.cpp: ########## @@ -524,12 +525,29 @@ void TaskControl::print_rq_sizes(std::ostream& os) { double TaskControl::get_cumulated_worker_time() { int64_t cputime_ns = 0; + int64_t now = butil::cpuwide_time_ns(); BAIDU_SCOPED_LOCK(_modify_group_mutex); for_each_task_group([&](TaskGroup* g) { if (g) { - cputime_ns += g->_cumulated_cputime_ns; + // With the acquire-release atomic operation, the CPU time of the bthread is + // only calculated once through `_cumulated_cputime_ns' or `_last_run_ns'. + cputime_ns += g->_cumulated_cputime_ns.load(butil::memory_order_acquire); + // The bthread is still running on the worker, + // so we need to add the elapsed time since it started. + // In extreme cases, before getting `_last_run_ns_in_tc', + // `_last_run_ns_in_tc' may have been updated multiple times, + // and `cputime_ns' will miss some cpu time, which is ok. + int64_t last_run_ns = g->_last_run_ns; + if (last_run_ns > _last_get_cumulated_time_ns) { + g->_last_run_ns_in_tc = last_run_ns; + cputime_ns += now - last_run_ns; + } else if (last_run_ns == g->_last_run_ns_in_tc) { + // The bthread is still running on the same worker. + cputime_ns += now - last_run_ns; + } Review Comment: Perhaps we can use the implicit feature of modern CPUs that 128-bit aligned load/store operations are atomic to implement atomic operations on combination of `_cumulated_cputime_ns` and `_last_run_ns`. x86_64: `_mm_load_si128`, `_mm_store_si128` Arm and later: `vld1q_s64` For scenarios that do not support 128-bit atomic operations, use the current PR implementation without lock. For a monitoring item used for debugging, this trade-off is reasonable. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: dev-unsubscr...@brpc.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org --------------------------------------------------------------------- To unsubscribe, e-mail: dev-unsubscr...@brpc.apache.org For additional commands, e-mail: dev-h...@brpc.apache.org