https://github.com/torvalds/linux
Revision 6bb8f311a870d6042e0310309eb3d607ae52fe3e authored by Anton Blanchard on 31 August 2011, 01:51:45 UTC, committed by Arnaldo Carvalho de Melo on 23 September 2011, 17:37:17 UTC
I took a profile that suggested 60% of total CPU time was in the hypervisor: ... 60.20% [H] 0x33d43c 4.43% [k] ._spin_lock_irqsave 1.07% [k] ._spin_lock Using perf stat to get the user/kernel/hypervisor breakdown contradicted this. The problem is we merge all unresolved samples into the one unknown bucket. If add a comparison by sample type to sort__sym_cmp we get the real picture: ... 57.11% [.] 0x80fbf63c 4.43% [k] ._spin_lock_irqsave 1.07% [k] ._spin_lock 0.65% [H] 0x33d43c So it was almost all userspace, not hypervisor as the initial profile suggested. I found another issue while adding this. Symbol sorting sometimes shows multiple entries for the unknown bucket: ... 16.65% [.] 0x6cd3a8 7.25% [.] 0x422460 5.37% [.] yylex 4.79% [.] malloc 4.78% [.] _int_malloc 4.03% [.] _int_free 3.95% [.] hash_source_code_string 2.82% [.] 0x532908 2.64% [.] 0x36b538 0.94% [H] 0x8000000000e132a4 0.82% [H] 0x800000000000e8b0 This happens because we aren't consistent with our sorting. On one hand we check to see if both symbols match and for two unresolved samples sym is NULL so we match: if (left->ms.sym == right->ms.sym) return 0; On the other hand we use sample IP for unresolved samples when comparing against a symbol: ip_l = left->ms.sym ? left->ms.sym->start : left->ip; ip_r = right->ms.sym ? right->ms.sym->start : right->ip; This means unresolved samples end up spread across the rbtree and we can't merge them all. If we use cmp_null all unresolved samples will end up in the one bucket and the output makes more sense: ... 39.12% [.] 0x36b538 5.37% [.] yylex 4.79% [.] malloc 4.78% [.] _int_malloc 4.03% [.] _int_free 3.95% [.] hash_source_code_string 2.26% [H] 0x800000000000e8b0 Acked-by: Eric B Munson <emunson@mgebm.net> Cc: Eric B Munson <emunson@mgebm.net> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Paul Mackerras <paulus@samba.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Ian Munsie <imunsie@au1.ibm.com> Link: http://lkml.kernel.org/r/20110831115145.4f598ab2@kryten Signed-off-by: Anton Blanchard <anton@samba.org> Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
1 parent 6a0e55d
Tip revision: 6bb8f311a870d6042e0310309eb3d607ae52fe3e authored by Anton Blanchard on 31 August 2011, 01:51:45 UTC
perf sort: Fix symbol sort output by separating unresolved samples by type
perf sort: Fix symbol sort output by separating unresolved samples by type
Tip revision: 6bb8f31
File | Mode | Size |
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Documentation | ||
arch | ||
block | ||
crypto | ||
drivers | ||
firmware | ||
fs | ||
include | ||
init | ||
ipc | ||
kernel | ||
lib | ||
mm | ||
net | ||
samples | ||
scripts | ||
security | ||
sound | ||
tools | ||
usr | ||
virt | ||
.gitignore | -rw-r--r-- | 1014 bytes |
.mailmap | -rw-r--r-- | 4.1 KB |
COPYING | -rw-r--r-- | 18.3 KB |
CREDITS | -rw-r--r-- | 92.6 KB |
Kbuild | -rw-r--r-- | 2.4 KB |
Kconfig | -rw-r--r-- | 252 bytes |
MAINTAINERS | -rw-r--r-- | 196.7 KB |
Makefile | -rw-r--r-- | 52.3 KB |
README | -rw-r--r-- | 17.0 KB |
REPORTING-BUGS | -rw-r--r-- | 3.3 KB |
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