Messages in this thread | | | Date | Mon, 14 May 2012 16:25:50 -0600 | From | David Ahern <> | Subject | Re: Perf events warning.. |
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On 5/14/12 4:20 PM, Peter Zijlstra wrote: > On Fri, 2012-05-11 at 08:43 -0700, Linus Torvalds wrote: >> Peter, Ingo, Arnaldo, >> google doesn't find a warning like this, so it can't be *too* >> commonly reported. >> >> Anyway, doing some profiling of git "make test" (wonderful load for >> doing lots of small processes that do lots of page faults etc), this >> WARN_ON_ONCE() triggered: >> >> ------------[ cut here ]------------ >> WARNING: at kernel/events/core.c:2066 task_ctx_sched_out+0x63/0x70() >> Hardware name: System Product Name >> Pid: 18120, comm: git Not tainted 3.4.0-rc6-00089-g4a01c681d58f-dirty #3 >> Call Trace: >> [<ffffffff810308c5>] warn_slowpath_common+0x75/0xb0 >> [<ffffffff810309c5>] warn_slowpath_null+0x15/0x20 >> [<ffffffff81096d63>] task_ctx_sched_out+0x63/0x70 >> [<ffffffff8109af06>] perf_event_comm+0x1d6/0x2e0 >> [<ffffffff81368ba8>] ? get_random_int+0x88/0xb0 >> [<ffffffff8102e1e2>] ? __mmdrop+0x62/0x90 >> [<ffffffff810e1f93>] set_task_comm+0x63/0x80 >> [<ffffffff810e3206>] setup_new_exec+0x86/0x250 >> [<ffffffff81126b69>] load_elf_binary+0x389/0x1930 >> [<ffffffff81125222>] ? load_misc_binary+0x292/0x390 >> [<ffffffff810bcbdd>] ? get_user_pages+0x4d/0x50 >> [<ffffffff810e13b2>] ? get_arg_page+0xa2/0xd0 >> [<ffffffff810e2b65>] search_binary_handler+0xd5/0x200 >> [<ffffffff811267e0>] ? elf_map+0x170/0x170 >> [<ffffffff810e300d>] do_execve_common.clone.39+0x37d/0x430 >> [<ffffffff810e30d6>] do_execve+0x16/0x20 >> [<ffffffff8100ab75>] sys_execve+0x45/0x70 >> [<ffffffff816b10ac>] stub_execve+0x6c/0xc0 >> ---[ end trace 6fccf3db70f1b560 ]--- >> >> any comments/ideas? > > So far I can't make any of the things I came up stick. You ran something > simple like: 'perf record -e cycles:pp -F 20000 make test' ? Or did you > do something more interesting?
By chance I just hit this: [ 31.528795] WARNING: at /mnt/sw/kernel-2.6.git/arch/x86/kernel/cpu/perf_event.c:1054 x86_pmu_start+0xdc/0x110() [ 31.528799] Hardware name: Bochs [ 31.528801] Modules linked in: nfs fscache auth_rpcgss nfs_acl lockd ip6t_REJECT nf_conntrack_ipv6 nf_defrag_ipv6 nf_conntrack_ipv4 nf_defrag_ipv4 xt_state ip6table_filter nf_conntrack ip6_tables virtio_net ppdev i2c_piix4 parport_pc parport i2c_core sunrpc virtio_blk [last unloaded: scsi_wait_scan] [ 31.528825] Pid: 959, comm: find Not tainted 3.4.0-rc6+ #1 [ 31.528827] Call Trace: [ 31.528835] [<ffffffff8105792f>] warn_slowpath_common+0x7f/0xc0 [ 31.528839] [<ffffffff8105798a>] warn_slowpath_null+0x1a/0x20 [ 31.528843] [<ffffffff8102543c>] x86_pmu_start+0xdc/0x110 [ 31.528847] [<ffffffff81025af2>] x86_pmu_enable+0x212/0x270 [ 31.528854] [<ffffffff81116466>] perf_event_context_sched_in+0xe6/0x100 [ 31.528857] [<ffffffff81118083>] perf_event_comm+0x103/0x2b0 [ 31.528863] [<ffffffff81184342>] set_task_comm+0x72/0xe0 [ 31.528867] [<ffffffff81184a1b>] setup_new_exec+0x8b/0x240 [ 31.528873] [<ffffffff811cc8b7>] load_elf_binary+0x3e7/0x19a0 [ 31.528879] [<ffffffff811443c2>] ? get_user_pages+0x52/0x60 [ 31.528883] [<ffffffff81182708>] ? get_user_arg_ptr+0x38/0x80 [ 31.528887] [<ffffffff81182bae>] search_binary_handler+0xee/0x340 [ 31.528891] [<ffffffff811cc4d0>] ? load_elf_library+0x230/0x230 [ 31.528895] [<ffffffff811847ff>] do_execve_common+0x36f/0x410 [ 31.528899] [<ffffffff811848da>] do_execve+0x3a/0x40 [ 31.528903] [<ffffffff8101d477>] sys_execve+0x47/0x70 [ 31.528908] [<ffffffff815f226c>] stub_execve+0x6c/0xc0 [ 31.528911] ---[ end trace ba6387065a9b9696 ]---
As for the something interesting part - not really: debugging the regression on 'perf stat --group -- find /usr >/dev/null'
David
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