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Violators will be prosecuted for from ; Tue, 13 Jun 2017 11:55:23 -0400 Subject: Re: [PATCH v2] perf: libdw support for powerpc [ping] To: Mark Wielaard References: <1496312681-20133-1-git-send-email-pbonzini@redhat.com> <593E81ED.8060606@linux.vnet.ibm.com> <1497354282.3755.201.camel@klomp.org> Cc: Paolo Bonzini , linux-kernel@vger.kernel.org, acme@kernel.org, "Naveen N. Rao" , linuxppc-dev@lists.ozlabs.org, Ravi Bangoria From: Ravi Bangoria Date: Tue, 13 Jun 2017 21:25:09 +0530 MIME-Version: 1.0 In-Reply-To: <1497354282.3755.201.camel@klomp.org> Content-Type: text/plain; charset=utf-8 Message-Id: <59400ADD.4090709@linux.vnet.ibm.com> List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Hi Mark, On Tuesday 13 June 2017 05:14 PM, Mark Wielaard wrote: > I see the same on very short runs. But when doing a slightly longer run, > even just using ls -lahR, which does some more work, then I do see user > backtraces. They are still missing for some of the early samples though. > It is as if there is a stack/memory address mismatch when the probe is > "too early" in ld.so. > > Could you do a test run on some program that does some more work to see > if you never get any user stack traces, or if you only not get them for > some specific probes? Thanks for checking. I tried a proper workload this time, but I still don't see any userspace callchain getting unwound. $ ./perf record --call-graph=dwarf -- zip -q -r temp.zip . [ perf record: Woken up 2891 times to write data ] [ perf record: Captured and wrote 723.290 MB perf.data (87934 samples) ] With libdw: $ LD_LIBRARY_PATH=/home/ravi/elfutils-git/usr/local/lib:\ /home/ravi/elfutils-git/usr/local/lib/elfutils/:$LD_LIBRARY_PATH\ ./perf script zip 16699 6857.354633: 37371 cycles:u: ecedc xmon_core (/usr/lib/debug/lib/modules/4.11.0-3.el7.ppc64le/vmlinux) 8c4fc __hash_page_64K (/usr/lib/debug/lib/modules/4.11.0-3.el7.ppc64le/vmlinux) 83450 hash_preload (/usr/lib/debug/lib/modules/4.11.0-3.el7.ppc64le/vmlinux) 7cc34 update_mmu_cache (/usr/lib/debug/lib/modules/4.11.0-3.el7.ppc64le/vmlinux) 330064 alloc_set_pte (/usr/lib/debug/lib/modules/4.11.0-3.el7.ppc64le/vmlinux) 330efc do_fault (/usr/lib/debug/lib/modules/4.11.0-3.el7.ppc64le/vmlinux) 334580 __handle_mm_fault (/usr/lib/debug/lib/modules/4.11.0-3.el7.ppc64le/vmlinux) 335040 handle_mm_fault (/usr/lib/debug/lib/modules/4.11.0-3.el7.ppc64le/vmlinux) 7bf94 do_page_fault (/usr/lib/debug/lib/modules/4.11.0-3.el7.ppc64le/vmlinux) 7bec4 do_page_fault (/usr/lib/debug/lib/modules/4.11.0-3.el7.ppc64le/vmlinux) 7be78 do_page_fault (/usr/lib/debug/lib/modules/4.11.0-3.el7.ppc64le/vmlinux) 1a4f8 handle_page_fault (/usr/lib/debug/lib/modules/4.11.0-3.el7.ppc64le/vmlinux) zip 16699 6857.354663: 300677 cycles:u: zip 16699 6857.354895: 584131 cycles:u: zip 16699 6857.355312: 589687 cycles:u: zip 16699 6857.355606: 560142 cycles:u: With libunwind: $ ./perf script zip 16699 6857.354633: 37371 cycles:u: ecedc xmon_core (/usr/lib/debug/lib/modules/4.11.0-3.el7.ppc64le/vmlinux) 8c4fc __hash_page_64K (/usr/lib/debug/lib/modules/4.11.0-3.el7.ppc64le/vmlinux) 83450 hash_preload (/usr/lib/debug/lib/modules/4.11.0-3.el7.ppc64le/vmlinux) 7cc34 update_mmu_cache (/usr/lib/debug/lib/modules/4.11.0-3.el7.ppc64le/vmlinux) 330064 alloc_set_pte (/usr/lib/debug/lib/modules/4.11.0-3.el7.ppc64le/vmlinux) 330efc do_fault (/usr/lib/debug/lib/modules/4.11.0-3.el7.ppc64le/vmlinux) 334580 __handle_mm_fault (/usr/lib/debug/lib/modules/4.11.0-3.el7.ppc64le/vmlinux) 335040 handle_mm_fault (/usr/lib/debug/lib/modules/4.11.0-3.el7.ppc64le/vmlinux) 7bf94 do_page_fault (/usr/lib/debug/lib/modules/4.11.0-3.el7.ppc64le/vmlinux) 7bec4 do_page_fault (/usr/lib/debug/lib/modules/4.11.0-3.el7.ppc64le/vmlinux) 7be78 do_page_fault (/usr/lib/debug/lib/modules/4.11.0-3.el7.ppc64le/vmlinux) 1a4f8 handle_page_fault (/usr/lib/debug/lib/modules/4.11.0-3.el7.ppc64le/vmlinux) 1920 _start (/usr/lib64/ld-2.17.so) zip 16699 6857.354663: 300677 cycles:u: fa38 _dl_new_object (/usr/lib64/ld-2.17.so) 3073 dl_main (/usr/lib64/ld-2.17.so) 2045b _dl_sysdep_start (/usr/lib64/ld-2.17.so) 1c7f _dl_start_final (/usr/lib64/ld-2.17.so) 5ce7 _dl_start (/usr/lib64/ld-2.17.so) 1937 _start (/usr/lib64/ld-2.17.so) zip 16699 6857.354895: 584131 cycles:u: 103d0 _dl_relocate_object (/usr/lib64/ld-2.17.so) zip 16699 6857.355312: 589687 cycles:u: df68 do_lookup_x (/usr/lib64/ld-2.17.so) e8d7 _dl_lookup_symbol_x (/usr/lib64/ld-2.17.so) 14bb3 _dl_fixup (/usr/lib64/ld-2.17.so) 1ef37 _dl_runtime_resolve (/usr/lib64/ld-2.17.so) 20bf7 copy_args (/usr/bin/zip) 286f main (/usr/bin/zip) 2497f generic_start_main.isra.0 (/usr/lib64/libc-2.17.so) 24b73 __libc_start_main (/usr/lib64/libc-2.17.so) zip 16699 6857.355606: 560142 cycles:u: 84764 _IO_getc (/usr/lib64/libc-2.17.so) c4d7 find_next_signature (/usr/bin/zip) 15c8b readzipfile (/usr/bin/zip) 3477 main (/usr/bin/zip) 2497f generic_start_main.isra.0 (/usr/lib64/libc-2.17.so) 24b73 __libc_start_main (/usr/lib64/libc-2.17.so) Right now, I'm busy with few other things so I'm not able to dig further. But I can look into this next week or so. Thanks, Ravi