linux – perf在用户和内核级别测量事件的选项是什么意思？

Question

Linux perf工具提供对cpu事件计数器的访问.它允许您指定要计数的事件以及何时计算这些事件.

https://perf.wiki.kernel.org/index.php/Tutorial

By default,events are measured at both user and kernel levels:

perf stat -e cycles dd if=/dev/zero of=/dev/null count=100000

To measure only at the user level,it is necessary to pass a modifier:

perf stat -e cycles:u dd if=/dev/zero of=/dev/null count=100000

To measure both user and kernel (explicitly):

perf stat -e cycles:uk dd if=/dev/zero of=/dev/null count=100000

从这一点开始,我预计这些周期：你的意思是“只运行非内核代码时才计算事件”,记录的计数不会映射到内核符号,但似乎并非如此.

这是一个例子：

perf record -e cycles:u du -sh ~
[...]
perf report --stdio -i perf.data
[...]
9.24%  du       [kernel.kallsyms]  [k] system_call
[...]
0.70%  du       [kernel.kallsyms]  [k] page_fault
[...]

如果我这样做但使用循环：uk然后我会报告更多的内核符号,所以事件修饰符确实有效.使用周期：k生成几乎只有内核符号的报告,但它确实包含一些libc符号.

这里发生了什么？这是预期的行为吗？我是否误解了链接文档中使用的语言？

链接文档还包括此表,如果有帮助,则使用略有不同的描述：

06001

编辑：更多信息：

cpu是Intel Haswell.具体型号为i7-5820K.

Distro是最新的Arch Linux(滚动版本计划),内核为4.1.6.

perf本身的版本是4.2.0.

EDIT2：

示例运行的输出更多.如您所见,周期：您主要报告非内核符号.我知道当您查看带注释的程序集输出时,perf有时会将错误属性计数到相邻指令.也许这是相关的？

周期：U

# perf record -e cycles:u du -sh ~
179G    /home/khouli
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.116 MB perf.data (2755 samples) ]
# sudo perf report --stdio -i perf.data
# To display the perf.data header info,please use --header/--header-only options.
#
#
# Total Lost Samples: 0
#
# Samples: 2K of event 'cycles:u'
# Event count (approx.): 661835375
#
# Overhead  Command  Shared Object      Symbol
# ........  .......  .................  ..............................
#
    11.02%  du       libc-2.22.so       [.] _int_malloc
     9.73%  du       libc-2.22.so       [.] _int_free
     9.24%  du       du                 [.] fts_read
     9.23%  du       [kernel.kallsyms]  [k] system_call
     4.17%  du       libc-2.22.so       [.] strlen
     4.17%  du       libc-2.22.so       [.] __memmove_sse2
     3.47%  du       libc-2.22.so       [.] __readdir64
     3.33%  du       libc-2.22.so       [.] malloc_consolidate
     2.87%  du       libc-2.22.so       [.] malloc
     1.83%  du       libc-2.22.so       [.] msort_with_tmp.part.0
     1.63%  du       libc-2.22.so       [.] __memcpy_avx_unaligned
     1.63%  du       libc-2.22.so       [.] __getdents64
     1.52%  du       libc-2.22.so       [.] free
     1.47%  du       libc-2.22.so       [.] __memmove_avx_unaligned
     1.44%  du       du                 [.] 0x000000000000e609
     1.41%  du       libc-2.22.so       [.] _wordcopy_bwd_dest_aligned
     1.19%  du       du                 [.] 0x000000000000e644
     0.93%  du       libc-2.22.so       [.] __fxstatat64
     0.85%  du       libc-2.22.so       [.] do_fcntl
     0.73%  du       [kernel.kallsyms]  [k] page_fault
[lots more symbols,almost all in du...]

周期：英国

# perf record -e cycles:uk du -sh ~
179G    /home/khouli
[ perf record: Woken up 1 times to write data ]
[ext4] with build id 0f47443e26a238299e8a5963737da23dd3530376 not found,continuing without symbols
[ perf record: Captured and wrote 0.120 MB perf.data (2856 samples) ]
# perf report --stdio -i perf.data
# To display the perf.data header info,please use --header/--header-only options.
#
#
# Total Lost Samples: 0
#
# Samples: 2K of event 'cycles:uk'
# Event count (approx.): 3118065867
#
# Overhead  Command  Shared Object      Symbol
# ........  .......  .................  ..............................................
#
    13.80%  du       [kernel.kallsyms]  [k] __d_lookup_rcu
     6.16%  du       [kernel.kallsyms]  [k] security_inode_getattr
     2.52%  du       [kernel.kallsyms]  [k] str2hashbuf_signed
     2.43%  du       [kernel.kallsyms]  [k] system_call
     2.35%  du       [kernel.kallsyms]  [k] half_md4_transform
     2.31%  du       [kernel.kallsyms]  [k] ext4_htree_store_dirent
     1.97%  du       [kernel.kallsyms]  [k] copy_user_enhanced_fast_string
     1.96%  du       libc-2.22.so       [.] _int_malloc
     1.93%  du       du                 [.] fts_read
     1.90%  du       [kernel.kallsyms]  [k] system_call_after_swapgs
     1.83%  du       libc-2.22.so       [.] _int_free
     1.44%  du       [kernel.kallsyms]  [k] link_path_walk
     1.33%  du       libc-2.22.so       [.] __memmove_sse2
     1.19%  du       [kernel.kallsyms]  [k] _raw_spin_lock
     1.19%  du       [kernel.kallsyms]  [k] __fget_light
     1.12%  du       [kernel.kallsyms]  [k] kmem_cache_alloc
     1.12%  du       [kernel.kallsyms]  [k] __ext4_check_dir_entry
     1.05%  du       [kernel.kallsyms]  [k] lockref_get_not_dead
     1.02%  du       [kernel.kallsyms]  [k] generic_fillattr
     0.95%  du       [kernel.kallsyms]  [k] do_dentry_open
     0.95%  du       [kernel.kallsyms]  [k] path_init
     0.95%  du       [kernel.kallsyms]  [k] lockref_put_return
     0.91%  du       libc-2.22.so       [.] do_fcntl
     0.91%  du       [kernel.kallsyms]  [k] ext4_getattr
     0.91%  du       [kernel.kallsyms]  [k] rb_insert_color
     0.88%  du       [kernel.kallsyms]  [k] __kmalloc
     0.88%  du       libc-2.22.so       [.] __readdir64
     0.88%  du       libc-2.22.so       [.] malloc
     0.84%  du       [kernel.kallsyms]  [k] ext4fs_dirhash
     0.84%  du       [kernel.kallsyms]  [k] __slab_free
     0.84%  du       [kernel.kallsyms]  [k] in_group_p
     0.81%  du       [kernel.kallsyms]  [k] get_empty_filp
     0.77%  du       libc-2.22.so       [.] malloc_consolidate
[more...]

周期：K

# perf record -e cycles:k du -sh ~
179G    /home/khouli
[ perf record: Woken up 1 times to write data ]
[ext4] with build id 0f47443e26a238299e8a5963737da23dd3530376 not found,continuing
without symbols
[ perf record: Captured and wrote 0.118 MB perf.data (2816 samples) ]
# perf report --stdio -i perf.data
# To display the perf.data header info,please use --header/--header-only options.
#
#
# Total Lost Samples: 0
#
# Samples: 2K of event 'cycles:k'
# Event count (approx.): 2438426748
#
# Overhead  Command  Shared Object      Symbol
# ........  .......  .................  ..............................................
#
    17.11%  du       [kernel.kallsyms]  [k] __d_lookup_rcu
     6.97%  du       [kernel.kallsyms]  [k] security_inode_getattr
     4.22%  du       [kernel.kallsyms]  [k] half_md4_transform
     3.10%  du       [kernel.kallsyms]  [k] str2hashbuf_signed
     3.01%  du       [kernel.kallsyms]  [k] system_call_after_swapgs
     2.59%  du       [kernel.kallsyms]  [k] ext4_htree_store_dirent
     2.24%  du       [kernel.kallsyms]  [k] copy_user_enhanced_fast_string
     2.14%  du       [kernel.kallsyms]  [k] lockref_get_not_dead
     1.86%  du       [kernel.kallsyms]  [k] ext4_getattr
     1.85%  du       [kernel.kallsyms]  [k] kfree
     1.68%  du       [kernel.kallsyms]  [k] __ext4_check_dir_entry
     1.53%  du       [kernel.kallsyms]  [k] __fget_light
     1.34%  du       [kernel.kallsyms]  [k] link_path_walk
     1.34%  du       [kernel.kallsyms]  [k] path_init
     1.22%  du       [kernel.kallsyms]  [k] __kmalloc
     1.22%  du       [kernel.kallsyms]  [k] kmem_cache_alloc
     1.14%  du       [kernel.kallsyms]  [k] do_dentry_open
     1.11%  du       [kernel.kallsyms]  [k] ext4_readdir
     1.07%  du       [kernel.kallsyms]  [k] __find_get_block_slow
     1.07%  du       libc-2.22.so       [.] do_fcntl
     1.04%  du       [kernel.kallsyms]  [k] _raw_spin_lock
     0.99%  du       [kernel.kallsyms]  [k] _raw_read_lock
     0.95%  du       libc-2.22.so       [.] __fxstatat64
     0.94%  du       [kernel.kallsyms]  [k] rb_insert_color
     0.94%  du       [kernel.kallsyms]  [k] generic_fillattr
     0.93%  du       [kernel.kallsyms]  [k] ext4fs_dirhash
     0.93%  du       [kernel.kallsyms]  [k] find_get_entry
     0.89%  du       [kernel.kallsyms]  [k] rb_next
     0.89%  du       [kernel.kallsyms]  [k] is_dx_dir
     0.89%  du       [kernel.kallsyms]  [k] in_group_p
     0.89%  du       [kernel.kallsyms]  [k] cp_new_stat
   [more...]

perf_event_paranoid

$cat /proc/sys/kernel/perf_event_paranoid
1

内核配置为perf

$cat /proc/config.gz | gunzip | grep -A70 'Kernel Perf'
# Kernel Performance Events And Counters
#
CONFIG_PERF_EVENTS=y
# CONFIG_DEBUG_PERF_USE_VMALLOC is not set
CONFIG_VM_EVENT_COUNTERS=y
CONFIG_SLUB_DEBUG=y
# CONFIG_COMPAT_BRK is not set
# CONFIG_SLAB is not set
CONFIG_SLUB=y
CONFIG_SLUB_cpu_PARTIAL=y
CONFIG_SYSTEM_TRUSTED_KEYRING=y
CONFIG_PROFILING=y
CONFIG_TRACEPOINTS=y
CONFIG_OPROFILE=m
# CONFIG_OPROFILE_EVENT_MULTIPLEX is not set
CONFIG_HAVE_OPROFILE=y
CONFIG_OPROFILE_NMI_TIMER=y
CONFIG_KPROBES=y
CONFIG_JUMP_LABEL=y
CONFIG_KPROBES_ON_FTRACE=y
CONFIG_UPROBES=y
# CONFIG_HAVE_64BIT_ALIGNED_ACCESS is not set
CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS=y
CONFIG_ARCH_USE_BUILTIN_BSWAP=y
CONFIG_KRETPROBES=y
CONFIG_USER_RETURN_NOTIFIER=y
CONFIG_HAVE_IOREMAP_PROT=y
CONFIG_HAVE_KPROBES=y
CONFIG_HAVE_KRETPROBES=y
CONFIG_HAVE_OPTPROBES=y
CONFIG_HAVE_KPROBES_ON_FTRACE=y
CONFIG_HAVE_ARCH_TRACEHOOK=y
CONFIG_HAVE_DMA_ATTRS=y
CONFIG_HAVE_DMA_CONTIGUOUS=y
CONFIG_GENERIC_SMP_IDLE_THREAD=y
CONFIG_HAVE_REGS_AND_STACK_ACCESS_API=y
CONFIG_HAVE_CLK=y
CONFIG_HAVE_DMA_API_DEBUG=y
CONFIG_HAVE_HW_BREAKPOINT=y
CONFIG_HAVE_MIXED_BREAKPOINTS_REGS=y
CONFIG_HAVE_USER_RETURN_NOTIFIER=y
CONFIG_HAVE_PERF_EVENTS_NMI=y
CONFIG_HAVE_PERF_REGS=y
CONFIG_HAVE_PERF_USER_STACK_DUMP=y
CONFIG_HAVE_ARCH_JUMP_LABEL=y
CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG=y
CONFIG_HAVE_ALIGNED_STRUCT_PAGE=y
CONFIG_HAVE_CMPXCHG_LOCAL=y
CONFIG_HAVE_CMPXCHG_DOUBLE=y
CONFIG_ARCH_WANT_COMPAT_IPC_PARSE_VERSION=y
CONFIG_ARCH_WANT_OLD_COMPAT_IPC=y
CONFIG_HAVE_ARCH_SECCOMP_FILTER=y
CONFIG_SECCOMP_FILTER=y
CONFIG_HAVE_CC_STACKPROTECTOR=y
CONFIG_CC_STACKPROTECTOR=y
# CONFIG_CC_STACKPROTECTOR_NONE is not set
# CONFIG_CC_STACKPROTECTOR_REGULAR is not set
CONFIG_CC_STACKPROTECTOR_STRONG=y
CONFIG_HAVE_CONTEXT_TRACKING=y
CONFIG_HAVE_VIRT_cpu_ACCOUNTING_GEN=y
CONFIG_HAVE_IRQ_TIME_ACCOUNTING=y
CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE=y
CONFIG_HAVE_ARCH_HUGE_VMAP=y
CONFIG_HAVE_ARCH_SOFT_DIRTY=y
CONFIG_MODULES_USE_ELF_RELA=y
CONFIG_HAVE_IRQ_EXIT_ON_IRQ_STACK=y
CONFIG_ARCH_HAS_ELF_RANDOMIZE=y
CONFIG_OLD_SIGSUSPEND3=y
CONFIG_COMPAT_OLD_SIGACTION=y

linux – perf在用户和内核级别测量事件的选项是什么意思？

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