perf

I am trying to trace function zap_pte_range from mm/memory.c using perf . But function is not listed in the perf probe -F . So is there a way to dynamically trace this function? I.e. with explicitly adding the tracepoint and recompiling the kernel? perf probe -a zap_pte_range gives: [kernel.kallsyms] with build id 33b15ec444475ee7806331034772f61666fa6719 not found, continuing without symbols Failed to find symbol zap_pte_range in kernel Error: Failed to add events. There is no such trace point. So apparently you cannot trace it the easy way. It seems that this function was inlined by compiler

一、手动安装ceph。 根据http://my.oschina.net/linuxhunter/blog/682013，手动安装jewel版本ceph到硬件服务器。 二、测试ceph集群的方法。 使用ceph自带的rados bench命令简单测试手动搭建ceph集群的性能，查看系统性能的工具使用perf命令。由于默认安装的ubuntu环境没有安装perf工具及其依赖，所有要手动安装perf工具。#apt-get install perf linux-tools-4.4.0-21-generic。安装完成后启用两个终端分别运行#perf top命令和#rados banch -p test_rbd 60 write --no-cleanup命令。 三、发现的问题。 在运行#perf top命令的终端上发现ceph-osd在调用ceph_crc32_sctp这个函数上占用了35%的CPU时间，而此时集群的压力并不大，因此决定从源代码上找找ceph_crc32_sctp为什么占用那么多的CPU时间。 ceph_crc32_sctp这个函数位于src/common/sctp_crc32.c这个文件中，只有ceph_choose_crc32函数调用ceph_crc32_sctp函数。分析ceph_choose_crc32这个函数不难发现，该函数根据当前CPU的架构来选择计算crc32的方法

I found mtrace by Dr.Clements. Although it is useful, it doesn't work normally in the situation I need. I intend to use the record to understand memory access pattern in different scenario. Can someone share the related experience? Any suggestion will be appreciated. 0313 Updated : I'm trying to use qemu-mtrace to boot ubuntu 16.04 with linux-mtrace(3.8.0), but it only show several error message and terminated. Hope some tool be able to log every access. $ ./qemu-system-x86_64 -mtrace-enable -mtrace-file mtrace.out -hda ubuntu.img -m 1024 Error: mtrace_entry_ascope (exit, syscall:xx) with no

I was using perf mem -t load record "commands" to profile system memory access latency. After, I run perf mem -D report and I got the following results: [root@mdtm-server wenji]# perf mem -D report # PID, TID, IP, ADDR, LOCAL WEIGHT, DSRC, SYMBOL 2054 2054 0xffffffff811186bf 0x016ffffe8fbffc804b0 49 0x68100842 /lib/modules/3.12.23/build/vmlinux:perf_event_aux_ctx 2054 2054 0xffffffff81321d6e 0xffff880c7fc87d44 7 0x68100142 /lib/modules/3.12.23/build/vmlinux:ghes_copy_tofrom_phys What does "ADDR", "DSRC", "SYMBOL" mean? IP - PC of the load/store instruction; SYMBOL - name of function,

For some reason, I can't sample ( perf record ) hardware cache events: # perf record -e L1-dcache-stores -a -c 100 -- sleep 5 [ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 0.607 MB perf.data (~26517 samples) ] # perf script but I can count them ( perf stat ): # perf stat -e L1-dcache-stores -a -- sleep 5 Performance counter stats for 'sleep 5': 711,781 L1-dcache-stores 5.000842990 seconds time elapsed I tried on different CPUs, OS versions (and kernel versions), perf versions but the result is the same. Is this an expected behaviour? What is the reason? Can

I want to understand which events can have the precise modifier on my CPU (Sandy Bridge). Intel Software Developer's Manual (Table 18-32. PEBS Performance Events for Intel Microarchitecture Code Name Sandy Bridge) contains only the following events: INST_RETIRED , UOPS_RETIRED , BR_INST_RETIRED , BR_MISP_RETIRED , MEM_UOPS_RETIRED , MEM_LOAD_UOPS_RETIRED , MEM_LOAD_UOPS_LLC_HIT_RETIRED . And SandyBridge_core_V15.json lists the same events with PEBS > 0. However there are some examples of using perf , which add :p to the cycles event. And I can successfully run perf record -e cycles:p on my

I know that I can get the total percentage of branch mispredictions during the execution of a program with perf stat . But how can I get the statistics for a specific branch ( if or switch statement in C code)? You can sample on the branch-misses event: sudo perf record -e branch-misses <yourapp> and then report it (and even selecting the function you're interested in): sudo perf report -n --symbols=<yourfunction> There you can access the annotated code and get some statistics for a given branch. Or directly annotate it with the perf command with --symbol option. 来源： https://stackoverflow.com