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Date: Tue, 15 May 2012 00:46:49 -0300
From: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
To: David Ahern <dsahern@gmail.com>
Cc: Namhyung Kim <namhyung.kim@lge.com>, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] perf-record: Create events initially disabled -- again
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Em Mon, May 14, 2012 at 09:28:07PM -0600, David Ahern escreveu:
> 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?

Here it is mostly:

[acme@sandy autotest]$ grep "model name" /proc/cpuinfo | sort -u
model name	: Intel(R) Core(TM) i7-2920XM CPU @ 2.50GHz

Sandy Bridge.

- Arnaldo
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