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

David Ahern
2012-05-15T03:28:13Z

On 5/14/12 7:52 PM, David Ahern wrote:
> 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 ]---

I think I'm getting dizzy, and I knew I tested the whole 'perf-stat -g'
thing. It works *fine* on a Westmere box (E5620); the above comments
apply to a VM on a Nehalem server (E5540). (host is running 3.4.0-rc7
kernel and -cpu host argument for qemu-kvm.)

Namhyung/Arnaldo: What processor are you using?

David