Messages in this thread | | | Date | Wed, 25 Jul 2012 14:11:21 +0200 | From | Jiri Olsa <> | Subject | Re: [PATCH 04/11] perf kvm: fix bug resolving guest kernel syms - v2 |
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On Fri, Jul 20, 2012 at 05:25:49PM -0600, David Ahern wrote: > Guest kernel symbols are not resolved despite passing the information > needed to resolve them. e.g., > > perf kvm --guest --guestmount=/tmp/guest-mount record -a -- sleep 1 > perf kvm --guest --guestmount=/tmp/guest-mount report --stdio > > 36.55% [guest/11399] [unknown] [g] 0xffffffff81600bc8 > 33.19% [guest/10474] [unknown] [g] 0x00000000c0116e00 > 30.26% [guest/11094] [unknown] [g] 0xffffffff8100a288 > 43.69% [guest/10474] [unknown] [g] 0x00000000c0103d90 > 37.38% [guest/11399] [unknown] [g] 0xffffffff81600bc8 > 12.24% [guest/11094] [unknown] [g] 0xffffffff810aa91d > 6.69% [guest/11094] [unknown] [u] 0x00007fa784d721c3 > > which is just pathetic. > > After a maddening 2 days sifting through perf minutia I found it -- > id_hdr_size is not initialized for guest machines. This shows up on the > report side as random garbage for the cpu and timestamp, e.g., > > 29816 7310572949125804849 0x1ac0 [0x50]: PERF_RECORD_MMAP ... > > That messes up the sample sorting such that synthesized guest maps are > processed last. > > With this patch you get a much more helpful report: > > 12.11% [guest/11399] [guest.kernel.kallsyms.11399] [g] irqtime_account_process_tick > 10.58% [guest/11399] [guest.kernel.kallsyms.11399] [g] run_timer_softirq > 6.95% [guest/11094] [guest.kernel.kallsyms.11094] [g] printk_needs_cpu > 6.50% [guest/11094] [guest.kernel.kallsyms.11094] [g] do_timer > 6.45% [guest/11399] [guest.kernel.kallsyms.11399] [g] idle_balance > 4.90% [guest/11094] [guest.kernel.kallsyms.11094] [g] native_read_tsc > ... > > v2: > - changed rbtree walk to use rb_first per Namhyung's suggestion > > Signed-off-by: David Ahern <dsahern@gmail.com> > Cc: Arnaldo Carvalho de Melo <acme@ghostprotocols.net> > Cc: Ingo Molnar <mingo@kernel.org> > Cc: Jiri Olsa <jolsa@redhat.com>
Tested-by: Jiri Olsa <jolsa@redhat.com>
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