From: Namhyung Kim <namhyung@kernel.org>
To: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>,
Ingo Molnar <mingo@kernel.org>,
linux-kernel@vger.kernel.org, Anton Blanchard <anton@au1.ibm.com>,
Jiri Olsa <jolsa@redhat.com>,
Arnaldo Carvalho de Melo <acme@redhat.com>
Subject: Re: [PATCH 01/32] perf tools powerpc: Cache the DWARF debug info
Date: Fri, 31 Oct 2014 12:10:17 +0900 [thread overview]
Message-ID: <87a94d6ijq.fsf@sejong.aot.lge.com> (raw)
In-Reply-To: <20141029212620.GC17916@us.ibm.com> (Sukadev Bhattiprolu's message of "Wed, 29 Oct 2014 14:26:20 -0700")
Hi Sukadev,
On Wed, 29 Oct 2014 14:26:20 -0700, Sukadev Bhattiprolu wrote:
> Namhyung Kim [namhyung@kernel.org] wrote:
> | I don't know how dwfl_report_offline() can make it to find out a mod
> | from pc as it's an (loaded) virtual address. Maybe I miss something or
> | is your dso's are prelinked?
>
> Scratching my head on this and a related issue.
>
> The code seems to work consistently on Fedora20 and we recently noticed
> that it does not work on RHEL7. Maybe related to the issue you point out.
>
> On Fedora20 objdump -D /usr/lib64/libc-2.18.so shows something like this:
>
> 00000080a7be3bf0 <.__random>:
> 80a7be3bf0: 7c 08 02 a6 mflr r0
> 80a7be3bf4: fb e1 ff f8 std r31,-8(r1)
> 80a7be3bf8: 60 00 00 00 nop
> 80a7be3bfc: 39 00 00 01 li r8,1
> 80a7be3c00: 3b e2 9a f0 addi r31,r2,-25872
> 80a7be3c04: 39 40 00 00 li r10,0
> 80a7be3c08: f8 01 00 10 std r0,16(r1)
> 80a7be3c0c: f8 21 ff 71 stdu r1,-144(r1)
> 80a7be3c10: 7d 20 f8 29 lwarx r9,0,r31,1
> 80a7be3c14: 7c 09 50 00 cmpw r9,r10
> 80a7be3c18: 40 82 00 0c bne 80a7be3c24 <.__random+0x34>
>
> and my small test program (and perf) can use the addresses to correctly
> say if LR is relevant or not.
Looks like it's prelink'ed.
>
> But on RHEL7, objdump shows addresses differently:
>
> 0000000000063870 <.__random>:
> 63870: 7c 08 02 a6 mflr r0
> 63874: fb e1 ff f8 std r31,-8(r1)
> 63878: 60 00 00 00 nop
> 6387c: 3b e2 9a e0 addi r31,r2,-25888
> 63880: 39 00 00 01 li r8,1
> 63884: 39 40 00 00 li r10,0
> 63888: f8 01 00 10 std r0,16(r1)
> 6388c: f8 21 ff 71 stdu r1,-144(r1)
> 63890: 7d 20 f8 29 lwarx r9,0,r31,1
>
> and perf and my test program fail. Not sure if this is something related
> to the way it is built.
Then I think struct dso might not be a proper place to cache since a dso
can be mapped to different locations/addresses and it has no idea about
the location.
Maybe it's worth move the caching logic to a different place like struct
thread as libunwind does now, and make it generic so that the arch's
can also get the benefit when unwinding. A problem I can expect is that
it will have thread x dso number of cache entries which can consume a
lot of memory and fd IMHO.
Thanks,
Namhyung
next prev parent reply other threads:[~2014-10-31 3:10 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-10-28 13:31 [GIT PULL 00/32] perf/core improvements and fixes Arnaldo Carvalho de Melo
2014-10-28 13:31 ` [PATCH 01/32] perf tools powerpc: Cache the DWARF debug info Arnaldo Carvalho de Melo
2014-10-29 6:39 ` Namhyung Kim
2014-10-29 21:26 ` Sukadev Bhattiprolu
2014-10-31 3:10 ` Namhyung Kim [this message]
2014-10-28 13:31 ` [PATCH 02/32] perf tools: Set thread->mg.machine in all places Arnaldo Carvalho de Melo
2014-10-28 13:31 ` [PATCH 03/32] perf tools: A thread's machine can be found via thread->mg->machine Arnaldo Carvalho de Melo
2014-10-28 13:31 ` [PATCH 04/32] perf thread: Adopt resolve_callchain method from machine Arnaldo Carvalho de Melo
2014-10-28 13:31 ` [PATCH 05/32] perf callchains: Use thread->mg->machine Arnaldo Carvalho de Melo
2014-10-28 13:32 ` [PATCH 06/32] perf tests: Remove misplaced __maybe_unused Arnaldo Carvalho de Melo
2014-10-28 13:32 ` [PATCH 07/32] perf tests: Use thread->mg->machine Arnaldo Carvalho de Melo
2014-10-28 13:32 ` [PATCH 08/32] perf tools: Add PARSE_OPT_DISABLED flag Arnaldo Carvalho de Melo
2014-10-28 13:32 ` [PATCH 09/32] perf tools: Export usage string and option table of perf record Arnaldo Carvalho de Melo
2014-10-28 13:32 ` [PATCH 10/32] perf kvm: Print kvm specific --help output Arnaldo Carvalho de Melo
2014-10-28 13:32 ` [PATCH 11/32] perf tools: Add support for exclusive option Arnaldo Carvalho de Melo
2014-10-28 13:32 ` [PATCH 12/32] perf probe: Use PARSE_OPT_EXCLUSIVE flag Arnaldo Carvalho de Melo
2014-10-28 13:32 ` [PATCH 13/32] perf callchain: Use global caching provided by libunwind Arnaldo Carvalho de Melo
2014-10-28 13:32 ` [PATCH 14/32] perf tools: Ensure return negative value when write header error Arnaldo Carvalho de Melo
2014-10-28 13:32 ` [PATCH 15/32] perf pmu: Let pmu's with no events show up on perf list Arnaldo Carvalho de Melo
2014-10-28 13:32 ` [PATCH 16/32] perf tools: Build programs to copy 32-bit compatibility Arnaldo Carvalho de Melo
2014-10-28 13:32 ` [PATCH 17/32] perf tools: Add support for 32-bit compatibility VDSOs Arnaldo Carvalho de Melo
2014-10-28 13:32 ` [PATCH 18/32] perf tools: Do not attempt to run perf-read-vdso32 if it wasn't built Arnaldo Carvalho de Melo
2014-10-28 13:32 ` [PATCH 19/32] perf tools: Make CPUINFO_PROC an array to support different kernel versions Arnaldo Carvalho de Melo
2014-10-28 13:32 ` [PATCH 20/32] perf pmu: Add proper error handling to print_pmu_events() Arnaldo Carvalho de Melo
2014-10-28 13:32 ` [PATCH 21/32] perf tools: Fix report -F abort for data without branch info Arnaldo Carvalho de Melo
2014-10-28 13:32 ` [PATCH 22/32] perf tools: Fix report -F in_tx " Arnaldo Carvalho de Melo
2014-10-28 13:32 ` [PATCH 23/32] perf tools: Fix report -F mispredict " Arnaldo Carvalho de Melo
2014-10-28 13:32 ` [PATCH 24/32] perf tools: Fix report -F symbol_to " Arnaldo Carvalho de Melo
2014-10-28 13:32 ` [PATCH 25/32] perf tools: Fix report -F symbol_from " Arnaldo Carvalho de Melo
2014-10-28 13:32 ` [PATCH 26/32] perf tools: Fix report -F dso_to " Arnaldo Carvalho de Melo
2014-10-28 13:32 ` [PATCH 27/32] perf tools: Fix report -F dso_from " Arnaldo Carvalho de Melo
2014-10-28 13:32 ` [PATCH 28/32] perf tools: Add facility to export data in database-friendly way Arnaldo Carvalho de Melo
2014-10-28 13:32 ` [PATCH 29/32] perf scripting python: Extend interface to export data in a " Arnaldo Carvalho de Melo
2014-10-28 13:32 ` [PATCH 30/32] perf script: Add Python script to export to postgresql Arnaldo Carvalho de Melo
2014-10-28 13:32 ` [PATCH 31/32] perf probe: Trivial typo fix for --demangle Arnaldo Carvalho de Melo
2014-10-28 13:32 ` [PATCH 32/32] perf probe: Add --quiet option to suppress output result message Arnaldo Carvalho de Melo
2014-10-29 9:11 ` [GIT PULL 00/32] perf/core improvements and fixes Ingo Molnar
2014-10-29 12:58 ` Arnaldo Carvalho de Melo
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