Re: [PATCH] perf-record: Create events initially disabled -- again

David Ahern
2012-05-15T01:52:49Z

On 5/14/12 8:54 AM, Arnaldo Carvalho de Melo wrote:
> Em Mon, May 14, 2012 at 08:21:02AM -0600, David Ahern escreveu:
>> On 5/14/12 7:09 AM, David Ahern wrote:
>>>> A problem I see is that it'll break group handling again:
>>>>
>>>> $ ./perf stat -g sleep 1
>>>>
>>>> Performance counter stats for 'sleep 1':
>>>>
>>>> <not counted> task-clock
>>>> <not counted> context-switches
>>>> <not counted> CPU-migrations
>>>> <not counted> page-faults
>>>> <not counted> cycles
>>>> <not counted> stalled-cycles-frontend
>>>> <not counted> stalled-cycles-backend
>>>> <not counted> instructions
>>>> <not counted> branches
>>>> <not counted> branch-misses
>>>>
>>>> 1.000868932 seconds time elapsed
>>>>
>>>> So I suggest changing perf_target__none() check to a proper one
>>>> (perf_target__no_cpu? - the name might be changed soon) for your
>>>> purpose.
>>>
>>> Something else is wrong then. I tested that command (saw your patch in
>>> the history) and it worked for me. Also, this code path does not affect
>>> perf-stat -- it touches perf-record and perf-test only.
>>
>> I think it is something else. I am running latest git tree
>> (3.4.0-rc7). perf from Linus' tree and acme/core both show:
>>
>> perf stat -g -- find /usr>/dev/null
>>
>> Performance counter stats for 'find /usr':
>>
>> <not counted> task-clock
>> <not counted> context-switches
>> <not counted> CPU-migrations
>> <not counted> page-faults
>> <not counted> cycles
>> <not counted> stalled-cycles-frontend
>> <not counted> stalled-cycles-backend
>> <not counted> instructions
>> <not counted> branches
>> <not counted> branch-misses
>>
>> 0.111976940 seconds time elapsed
>>
>> (Using find to make sure some work is done as opposed to sleep;
>> openssl speed also shows the above.)
>
> [acme@sandy ~]$ perf stat -g -- find /usr>/dev/null
> find: `/usr/lib64/audit': Permission denied
> ^Cfind: Interrupt
>
> Performance counter stats for 'find /usr':
>
> <not counted> task-clock
> <not counted> context-switches
> <not counted> CPU-migrations
> <not counted> page-faults
> <not counted> cycles
> <not counted> stalled-cycles-frontend
> <not counted> stalled-cycles-backend
> <not counted> instructions
> <not counted> branches
> <not counted> branch-misses
>
> 1.282060271 seconds time elapsed
>
>
> [acme@sandy ~]$ uname -r
> 3.4.0-rc4-uprobes+
>
> But:
>
> [acme@felicio linux]$ uname -r
> 3.4.0-rc3+
> [acme@felicio linux]$ perf stat -g -- find /usr>/dev/null
> ^Cfind: Interrupt
>
> Performance counter stats for 'find /usr':
>
> 126.499751 task-clock # 0.122 CPUs utilized
> <not counted> context-switches
> <not counted> CPU-migrations
> <not counted> page-faults
> 366,694,182 cycles # 2.899 GHz
> 151,332,137 stalled-cycles-frontend # 41.27% frontend cycles idle
> 103,373,418 stalled-cycles-backend # 28.19% backend cycles idle
> 408,309,250 instructions # 1.11 insns per cycle
> # 0.37 stalled cycles
> # per insn
> 77,453,802 branches # 612.284 M/sec
> 1,703,728 branch-misses # 2.20% of all branches
>
> 1.032917277 seconds time elapsed
>
>
> [acme@felicio linux]$
>
> Bisecting...
>
> - Arnaldo

Seems like a few issues going on here. In all case the command run is:
perf stat -g -- find / >/dev/null

v3.1 kernel, v3.1 perf command -- command runs fine and generates output.

v3.2 kernel, v3.2 perf command -- fails - no output and nothing in dmesg.

Using latest acme/core version of perf generates a WARNING on all
versions tried - v3.1, v3.2, v3.4-rc3, and v3.4-rc7:

[ 143.964857] ------------[ cut here ]------------
[ 143.964870] WARNING: at
/mnt/sw/kernels/kernel-2.6.git/arch/x86/kernel/cpu/perf_event.c:860
x86_pmu_start+0xdc/0x110()
[ 143.964873] Hardware name: Bochs
[ 143.964875] Modules linked in: lockd ip6t_REJECT nf_conntrack_ipv6
nf_conntrack_ipv4 nf_defrag_ipv6 nf_defrag_ipv4 xt_state nf_conntrack
ip6table_filter ip6_tables ppdev parport_pc parport virtio_net i2c_piix4
i2c_core sunrpc virtio_blk [last unloaded: scsi_wait_scan]
[ 143.964897] Pid: 968, comm: find Not tainted 3.2.0 #1
[ 143.964900] Call Trace:
[ 143.964908] [<ffffffff8106dd2f>] warn_slowpath_common+0x7f/0xc0
[ 143.964913] [<ffffffff8106dd8a>] warn_slowpath_null+0x1a/0x20
[ 143.964917] [<ffffffff810248bc>] x86_pmu_start+0xdc/0x110
[ 143.964921] [<ffffffff81024f32>] x86_pmu_enable+0x212/0x270
[ 143.964928] [<ffffffff8110f946>] perf_event_context_sched_in+0xe6/0x100
[ 143.964932] [<ffffffff8111131e>] perf_event_comm+0x11e/0x330
[ 143.964940] [<ffffffff81378284>] ? get_random_int+0x74/0x90
[ 143.964947] [<ffffffff8117be40>] set_task_comm+0x60/0x70
[ 143.964951] [<ffffffff8117c541>] setup_new_exec+0xe1/0x2d0
[ 143.964958] [<ffffffff811c47ec>] load_elf_binary+0x3ec/0x1a10
[ 143.964972] [<ffffffff8113c672>] ? get_user_pages+0x52/0x60
[ 143.964977] [<ffffffff8117a168>] ? get_user_arg_ptr+0x38/0x80
[ 143.964982] [<ffffffff8117af2c>] search_binary_handler+0xec/0x300
[ 143.964986] [<ffffffff811c4400>] ? do_mmap+0x40/0x40
[ 143.964990] [<ffffffff8117c2eb>] do_execve_common+0x2ab/0x330
[ 143.964994] [<ffffffff8117c3aa>] do_execve+0x3a/0x40
[ 143.964998] [<ffffffff8101d347>] sys_execve+0x47/0x70
[ 143.965010] [<ffffffff815d9bdc>] stub_execve+0x6c/0xc0
[ 143.965013] ---[ end trace 8de43f6b89ac81e1 ]---

David