I run a perf session looks like this in my KDE/Plasma desktop-environment: [ PERF SESSION ]
1016 2020-08-13 09:57:24 echo 1 > /proc/sys/kernel/sched_schedstats 1017 2020-08-13 09:57:24 echo prandom_u32 >> /sys/kernel/debug/tracing/set_event 1018 2020-08-13 09:57:24 echo traceon > /sys/kernel/debug/tracing/events/random/prandom_u32/trigger 1019 2020-08-13 09:57:25 echo 1 > /sys/kernel/debug/tracing/events/enable 1020 2020-08-13 09:57:32 sysctl -n kernel.sched_schedstats 1021 2020-08-13 09:57:32 cat /sys/kernel/debug/tracing/events/enable 1022 2020-08-13 09:57:32 grep prandom_u32 /sys/kernel/debug/tracing/set_event 1023 2020-08-13 09:57:33 cat /sys/kernel/debug/tracing/events/random/prandom_u32/trigger root# /home/dileks/bin/perf record -a -g -e random:prandom_u32 sleep 5 Simple-Test: Press F5 in Firefox in each opened tab (5 tabs in total) root# /home/dileks/bin/perf report --no-children --stdio > /tmp/perf-report.txt - Sedat - [ perf-report.txt ] # To display the perf.data header info, please use --header/--header-only options. # # # Total Lost Samples: 0 # # Samples: 273 of event 'random:prandom_u32' # Event count (approx.): 273 # # Overhead Command Shared Object Symbol # ........ ............... ................. ............... # 27.47% firefox-esr [kernel.kallsyms] [k] prandom_u32 | ---prandom_u32 prandom_u32 shmem_get_inode shmem_mknod path_openat do_filp_open do_sys_openat2 __x64_sys_openat do_syscall_64 entry_SYSCALL_64_after_hwframe __open64 0x7a6f6d2e67726f2f 13.19% DNS Resolver #9 [kernel.kallsyms] [k] prandom_u32 | ---prandom_u32 prandom_u32 | |--5.86%--__ip4_datagram_connect | ip4_datagram_connect | __sys_connect | __x64_sys_connect | do_syscall_64 | entry_SYSCALL_64_after_hwframe | | | |--4.40%--__libc_connect | | 0x2c1 | | | --1.47%--connect | PR_GetAddrInfoByName | |--2.93%--udp_lib_get_port | inet_dgram_connect | __sys_connect | __x64_sys_connect | do_syscall_64 | entry_SYSCALL_64_after_hwframe | | | |--2.20%--__libc_connect | | 0x2c1 | | | --0.73%--connect | PR_GetAddrInfoByName | |--2.20%--__ip_select_ident | __ip_make_skb | ip_make_skb | udp_sendmsg | __sys_sendto | __x64_sys_sendto | do_syscall_64 | entry_SYSCALL_64_after_hwframe | __libc_send | --2.20%--netlink_autobind netlink_bind __sys_bind __x64_sys_bind do_syscall_64 entry_SYSCALL_64_after_hwframe bind getaddrinfo PR_GetAddrInfoByName 12.45% FS Broker 7060 [kernel.kallsyms] [k] prandom_u32 | ---prandom_u32 prandom_u32 shmem_get_inode shmem_mknod path_openat do_filp_open do_sys_openat2 __x64_sys_openat do_syscall_64 entry_SYSCALL_64_after_hwframe __open64 0x7a6f6d2e67726f2f 8.79% FS Broker 6334 [kernel.kallsyms] [k] prandom_u32 | ---prandom_u32 prandom_u32 shmem_get_inode shmem_mknod path_openat do_filp_open do_sys_openat2 __x64_sys_openat do_syscall_64 entry_SYSCALL_64_after_hwframe __open64 0x7a6f6d2e67726f2f 8.06% FS Broker 7161 [kernel.kallsyms] [k] prandom_u32 | ---prandom_u32 prandom_u32 shmem_get_inode shmem_mknod path_openat do_filp_open do_sys_openat2 __x64_sys_openat do_syscall_64 entry_SYSCALL_64_after_hwframe __open64 0x7a6f6d2e67726f2f 8.06% FS Broker 7195 [kernel.kallsyms] [k] prandom_u32 | ---prandom_u32 prandom_u32 shmem_get_inode shmem_mknod path_openat do_filp_open do_sys_openat2 __x64_sys_openat do_syscall_64 entry_SYSCALL_64_after_hwframe __open64 0x7a6f6d2e67726f2f 7.33% FS Broker 7126 [kernel.kallsyms] [k] prandom_u32 | ---prandom_u32 prandom_u32 shmem_get_inode shmem_mknod path_openat do_filp_open do_sys_openat2 __x64_sys_openat do_syscall_64 entry_SYSCALL_64_after_hwframe __open64 0x7a6f6d2e67726f2f 7.33% Socket Thread [kernel.kallsyms] [k] prandom_u32 | ---prandom_u32 prandom_u32 tcp_v4_connect __inet_stream_connect inet_stream_connect __sys_connect __x64_sys_connect do_syscall_64 entry_SYSCALL_64_after_hwframe __libc_connect 4.40% Cache2 I/O [kernel.kallsyms] [k] prandom_u32 | ---prandom_u32 prandom_u32 __ext4_new_inode ext4_create path_openat do_filp_open do_sys_openat2 __x64_sys_openat do_syscall_64 entry_SYSCALL_64_after_hwframe __open64 0x61632e2f736b656c 1.10% Xorg [kernel.kallsyms] [k] prandom_u32 | ---prandom_u32 prandom_u32 shmem_get_inode __shmem_file_setup create_shmem i915_gem_object_create_region i915_gem_create_ioctl drm_ioctl_kernel drm_ioctl __se_sys_ioctl do_syscall_64 entry_SYSCALL_64_after_hwframe ioctl 0.73% QSGRenderThread [kernel.kallsyms] [k] prandom_u32 | ---prandom_u32 prandom_u32 shmem_get_inode __shmem_file_setup create_shmem i915_gem_object_create_region i915_gem_create_ioctl drm_ioctl_kernel drm_ioctl __se_sys_ioctl do_syscall_64 entry_SYSCALL_64_after_hwframe ioctl 0.37% DOM Worker [kernel.kallsyms] [k] prandom_u32 | ---prandom_u32 prandom_u32 __ext4_new_inode ext4_create path_openat do_filp_open do_sys_openat2 __x64_sys_openat do_syscall_64 entry_SYSCALL_64_after_hwframe __open64 0x6f6d2e2f736b656c 0.37% cupsd [kernel.kallsyms] [k] prandom_u32 | ---prandom_u32 prandom_u32 __ext4_new_inode ext4_create path_openat do_filp_open do_sys_openat2 __x64_sys_openat do_syscall_64 entry_SYSCALL_64_after_hwframe __open64 0x7263736275732f73 0.37% mozStorage #8 [kernel.kallsyms] [k] prandom_u32 | ---prandom_u32 prandom_u32 __ext4_new_inode ext4_create path_openat do_filp_open do_sys_openat2 __x64_sys_openat do_syscall_64 entry_SYSCALL_64_after_hwframe __open64 0x6f6d2e2f736b656c # Samples: 0 of event 'dummy:HG' # Event count (approx.): 0 # # Overhead Command Shared Object Symbol # ........ ....... ............. ...... # # # (Tip: Print event counts in CSV format with: perf stat -x,) # - EOF -