幸运的是,在处理器内部,有很多 PMU event,可用来帮助我们分析造成 CPU stall 的原因。用好 PMU 需要我们熟悉处理器微架构,可以参考 Intel SDM。 4. 最佳实践是什么? 如果IPC < 1.0, 很可能是 Memory stall 占主导,可从软件和硬件两个方面考虑这个问题。软件方面:减少不必要的访存操作,提升 cache 命中率,尽量...
幸运的是,在处理器内部,有很多 PMU event,可用来帮助我们分析造成 CPU stall 的原因。用好 PMU 需要我们熟悉处理器微架构,可以参考 Intel SDM。 4. 最佳实践是什么? 如果IPC < 1.0, 很可能是 Memory stall 占主导,可从软件和硬件两个方面考虑这个问题。软件方面:减少不必要的访存操作,提升 cache 命中率,尽量...
Off-CPU analysis can be an effective way to locate types of latency where threads block and wait for some other event. By tracing this from the kernel scheduler functions that context switch threads, all off-CPU latency types can be analyzed in the same way, without needing to trace multiple...
cpu, task, group_leader, NULL, NULL, NULL, cgroup_fd); pmu = event->pmu; // 3.创建perf_event_context ctx对象, ctx保存了事件上下文的各种信息 ctx = find_get_context(pmu, task, event); // 4.创建一个文件,指定 perf 类型文件的操作函数为 perf_fops event_file = anon_inode_...
fcba7e2 components bootloader bt driver esp32 hwcrypto include ld lib Kconfig abi.cpp brownout.c component.mk cpu_freq.c cpu_start.c crosscore_int.c deepsleep.c event_default_handlers.c event_loop.c gdbstub.c heap_alloc_caps.c int_wdt.c ...
bt driver esp32 hwcrypto include ld lib test Kconfig Makefile.projbuild abi.cpp brownout.c component.mk cpu_freq.c cpu_start.c cpu_util.c crosscore_int.c deepsleep.c event_default_handlers.c event_loop.c freertos_hooks.c gdbstub.c ...
A CPI < 1 is typical for instruction bound code, while a CPI > 1 may show up for a stall cycle bound application, also likely memory bound. If a CPI value exceeds the threshold, the VTune Profiler highlights this value in pink. A high value for this ratio (>1) indicates that ov...
Bit 01: Supports treating interrupts as break-event for MWAIT, even when interrupts disabled. Bits 31-02: Reserved. EDX Bits 03-00: Number of C0* sub C-states supported using MWAIT. Bits 07-04: Number of C1* sub C-states supported using MWAIT. Bits 11-08: Number of C2* sub C-...
To place the device in PM2 or PM6, the core should execute a wait-for-interrupt (WFI) or wait-for-event (WFE) instruction. If the WFI instruction is called from an interrupt service routine, the interrupt that wakes the device from PM2 or PM6 must be of a sufficient priority to be ...
[56377.012166] INFO: rcu_sched self-detected stall on CPU { [56377.012167] INFO: rcu_sched self-detected stall on CPU [56377.012168] INFO: rcu_sched self-detected stall on CPU [56377.012169] INFO: rcu_sched self-detected stall on CPU [56377.012170] 47 [56377.012171] { [56377.012171] { [...