Messages in this thread | | | Date | Wed, 17 Apr 2019 16:40:02 +0200 | From | Jiri Olsa <> | Subject | Re: [PATCH v1] perf record: collect user registers set jointly with dwarf stacks |
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On Wed, Apr 17, 2019 at 11:35:42AM -0300, Arnaldo Carvalho de Melo wrote: > Em Wed, Apr 17, 2019 at 09:39:52AM +0200, Jiri Olsa escreveu: > > On Mon, Apr 15, 2019 at 06:36:13PM +0300, Alexey Budankov wrote: > > > > > > When dwarf stacks are collected jointly with user specified register > > > set using --user-regs option like below the full register context is > > > still captured on a sample: > > > > > > $ perf record -g --call-graph dwarf,1024 --user-regs=IP,SP,BP -- matrix.gcc.g.O3 > > > > > > 188143843893585 0x6b48 [0x4f8]: PERF_RECORD_SAMPLE(IP, 0x4002): 23828/23828: 0x401236 period: 1363819 addr: 0x7ffedbdd51ac > > > ... FP chain: nr:0 > > > ... user regs: mask 0xff0fff ABI 64-bit > > > .... AX 0x53b > > > .... BX 0x7ffedbdd3cc0 > > > .... CX 0xffffffff > > > .... DX 0x33d3a > > > .... SI 0x7f09b74c38d0 > > > .... DI 0x0 > > > .... BP 0x401260 > > > .... SP 0x7ffedbdd3cc0 > > > .... IP 0x401236 > > > .... FLAGS 0x20a > > > .... CS 0x33 > > > .... SS 0x2b > > > .... R8 0x7f09b74c3800 > > > .... R9 0x7f09b74c2da0 > > > .... R10 0xfffffffffffff3ce > > > .... R11 0x246 > > > .... R12 0x401070 > > > .... R13 0x7ffedbdd5db0 > > > .... R14 0x0 > > > .... R15 0x0 > > > ... ustack: size 1024, offset 0xe0 > > > . data_src: 0x5080021 > > > ... thread: stack_test2.g.O:23828 > > > ...... dso: /root/abudanko/stacks/stack_test2.g.O3 > > > > > > After applying the change suggested in the patch the sample data contain > > > only user specified register values: > > > > > > $ perf record -g --call-graph dwarf,1024 --user-regs=IP,SP,BP -- matrix.gcc.g.03 > > > > > > 188368474305373 0x5e40 [0x470]: PERF_RECORD_SAMPLE(IP, 0x4002): 23839/23839: 0x401236 period: 1260507 addr: 0x7ffd3d85e96c > > > ... FP chain: nr:0 > > > ... user regs: mask 0x1c0 ABI 64-bit > > > .... BP 0x401260 > > > .... SP 0x7ffd3d85cc20 > > > .... IP 0x401236 > > > ... ustack: size 1024, offset 0x58 > > > . data_src: 0x5080021 > > > ... thread: stack_test2.g.O:23839 > > > ...... dso: /root/abudanko/stacks/stack_test2.g.O3 > > > > > > Signed-off-by: Alexey Budankov <alexey.budankov@linux.intel.com> > > > > Acked-by: Jiri Olsa <jolsa@kernel.org> > > So, there are registers that are needed to do the DWARF unwinding, > right? But at the same time, if the user says only some are needed, he > better know what they're doing and ask for at least the registers needed > for the unwinding process to be successfull, right?
yep, that's how understand that
jirka
> > - Arnaldo > > > thanks, > > jirka > > > > > --- > > > tools/perf/util/evsel.c | 3 ++- > > > 1 file changed, 2 insertions(+), 1 deletion(-) > > > > > > diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c > > > index 84cfb9fe2fc6..29a223b4c699 100644 > > > --- a/tools/perf/util/evsel.c > > > +++ b/tools/perf/util/evsel.c > > > @@ -702,7 +702,8 @@ static void __perf_evsel__config_callchain(struct perf_evsel *evsel, > > > if (!function) { > > > perf_evsel__set_sample_bit(evsel, REGS_USER); > > > perf_evsel__set_sample_bit(evsel, STACK_USER); > > > - attr->sample_regs_user |= PERF_REGS_MASK; > > > + if (!opts->sample_user_regs) > > > + attr->sample_regs_user |= PERF_REGS_MASK; > > > attr->sample_stack_user = param->dump_size; > > > attr->exclude_callchain_user = 1; > > > } else { > > > -- > > > 2.20.1 > > > > > -- > > - Arnaldo
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