[英]“perf stat” returning <not supported> for all events on ARCH Linux ARM
我有perf
我的Cortex-A15的Chromebook運行Arch Linux的ARM工作的罰款。
我更新了pacman
以獲得gcc-5.3,它要求更新我的內核,所以我做了。
現在perf
的回報:
[cortex@alarm Speckle]$ perf stat uname -a
Linux alarm 3.8.11-3-ARCH #1 SMP Wed Jan 20 13:44:59 MST 2016 armv7l GNU/Linux
Performance counter stats for 'uname -a':
<not supported> task-clock
<not supported> context-switches
<not supported> cpu-migrations
<not supported> page-faults
<not supported> cycles
<not supported> stalled-cycles-frontend
<not supported> stalled-cycles-backend
<not supported> instructions
<not supported> branches
<not supported> branch-misses
0.002148765 seconds time elapsed
如果我運行perf list
,它告訴我它應該支持以下事件:
[cortex@alarm Speckle]$ perf list
List of pre-defined events (to be used in -e):
branch-instructions OR branches [Hardware event]
branch-misses [Hardware event]
bus-cycles [Hardware event]
cache-misses [Hardware event]
cache-references [Hardware event]
cpu-cycles OR cycles [Hardware event]
instructions [Hardware event]
ref-cycles [Hardware event]
並檢查我的內核配置,似乎仍然應該支持perf
。
[cortex@alarm Speckle]$ zgrep PERF /proc/config.gz
CONFIG_CGROUP_PERF=y
CONFIG_HAVE_PERF_EVENTS=y
CONFIG_PERF_USE_VMALLOC=y
CONFIG_PERF_EVENTS=y
# CONFIG_DEBUG_PERF_USE_VMALLOC is not set
CONFIG_HW_PERF_EVENTS=y
# CONFIG_CPU_FREQ_DEFAULT_GOV_PERFORMANCE is not set
CONFIG_CPU_FREQ_GOV_PERFORMANCE=y
# CONFIG_CLS_U32_PERF is not set
# CONFIG_DEVFREQ_GOV_PERFORMANCE is not set
如果我嘗試使用ocount / oprofile,它似乎可以工作:
[cortex@alarm ~]$ ocount --events INST_RETIRED uname -a
Linux alarm 3.8.11-3-ARCH #1 SMP Wed Jan 20 13:44:59 MST 2016 armv7l GNU/Linux
Events were actively counted for 1598252 nanoseconds.
Event counts (actual) for /usr/bin/uname:
Event Count % time counted
INST_RETIRED 609,518 100.00
查看pacman的日志,看起來這是發生內核更改的地方嗎?
[2016-04-26 06:24] [ALPM] upgraded libtool (2.4.6-3 -> 2.4.6-4)
[2016-04-26 06:27] [ALPM] upgraded linux-firmware (20150904.6ebf5d5-1 -> 20160315.deb1d83-1)
[2016-04-26 06:27] [ALPM] upgraded linux-peach (3.8.11-2 -> 3.8.11-3)
[2016-04-26 06:27] [ALPM-SCRIPTLET] >>> Updating module dependencies. Please wait ...
[2016-04-26 06:27] [ALPM-SCRIPTLET] A new kernel version needs to be flashed onto /dev/sda1.
[2016-04-26 06:27] [ALPM-SCRIPTLET] Do you want to do this now? [y|N]
[2016-04-26 06:28] [ALPM-SCRIPTLET] 8752+0 records in
[2016-04-26 06:28] [ALPM-SCRIPTLET] 8752+0 records out
[2016-04-26 06:28] [ALPM-SCRIPTLET] 4481024 bytes (4.5 MB, 4.3 MiB) copied, 12.7236 s, 352 kB/s
我是怎么搞砸了?我如何獲得perf
回來?
我發現的解決方案是將性能從perf 4.5-2
降級到perf 4.3-1
。
cd /var/cache/pacman/pkg/
sudo pacman -U perf-4.3-1-armv7h.pkg.tar.xz
現在,運行perf stat ls
返回我期望的計數器。
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