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| author |   Anton Blanchard <anton@au1.ibm.com> | 2014-02-12 17:18:50 +1100 |
|---|---|---|
| committer |   Benjamin Herrenschmidt <benh@kernel.crashing.org> | 2014-02-17 11:19:37 +1100 |
| commit | 24b659a13866b935eca72748ce725279bd3c4466 (patch) | |
| tree | 835ca5a6661974e9e160f921b54cf433f8b1733c /arch/powerpc/kernel/vdso64 | |
| parent | powerpc: Link VDSOs at 0x0 (diff) | |
| download | linux-dev-24b659a13866b935eca72748ce725279bd3c4466.tar.xz linux-dev-24b659a13866b935eca72748ce725279bd3c4466.zip | |
powerpc: Use unstripped VDSO image for more accurate profiling data
We are seeing a lot of hits in the VDSO that are not resolved by perf.
A while(1) gettimeofday() loop shows the issue:
27.64% [vdso] [.] 0x000000000000060c
22.57% [vdso] [.] 0x0000000000000628
16.88% [vdso] [.] 0x0000000000000610
12.39% [vdso] [.] __kernel_gettimeofday
6.09% [vdso] [.] 0x00000000000005f8
3.58% test [.] 00000037.plt_call.gettimeofday@@GLIBC_2.18
2.94% [vdso] [.] __kernel_datapage_offset
2.90% test [.] main
We are using a stripped VDSO image which means only symbols with
relocation info can be resolved. There isn't a lot of point to
stripping the VDSO, the debug info is only about 1kB:
4680 arch/powerpc/kernel/vdso64/vdso64.so
5815 arch/powerpc/kernel/vdso64/vdso64.so.dbg
By using the unstripped image, we can resolve all the symbols in the
VDSO and the perf profile data looks much better:
76.53% [vdso] [.] __do_get_tspec
12.20% [vdso] [.] __kernel_gettimeofday
5.05% [vdso] [.] __get_datapage
3.20% test [.] main
2.92% test [.] 00000037.plt_call.gettimeofday@@GLIBC_2.18
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Diffstat (limited to 'arch/powerpc/kernel/vdso64')
| -rw-r--r-- | arch/powerpc/kernel/vdso64/vdso64_wrapper.S | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/powerpc/kernel/vdso64/vdso64_wrapper.S b/arch/powerpc/kernel/vdso64/vdso64_wrapper.S index 8df9e2463007..df60fca6a13d 100644 --- a/arch/powerpc/kernel/vdso64/vdso64_wrapper.S +++ b/arch/powerpc/kernel/vdso64/vdso64_wrapper.S @@ -6,7 +6,7 @@ .globl vdso64_start, vdso64_end .balign PAGE_SIZE vdso64_start: - .incbin "arch/powerpc/kernel/vdso64/vdso64.so" + .incbin "arch/powerpc/kernel/vdso64/vdso64.so.dbg" .balign PAGE_SIZE vdso64_end: |