Move the list of symbols we skip into an array, making it
easier to add new ones.
Signed-off-by: Anton Blanchard <anton@samba.org>
Cc: a.p.zijlstra@chello.nl
Cc: paulus@samba.org
LKML-Reference: <20090630230140.904782938@samba.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
The zlib devel libraries may not be installed and since we aren't
using zlib we may as well remove it.
Signed-off-by: Anton Blanchard <anton@samba.org>
Cc: a.p.zijlstra@chello.nl
Cc: paulus@samba.org
LKML-Reference: <20090630230140.802078956@samba.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Fix a copy and paste error, -z was setting the group option.
Signed-off-by: Anton Blanchard <anton@samba.org>
Cc: a.p.zijlstra@chello.nl
Cc: paulus@samba.org
LKML-Reference: <20090630230140.714204656@samba.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
So that we can filter by comm. Symbols in other comms won't be
accounted for.
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Paul Mackerras <paulus@samba.org>
LKML-Reference: <1246399282-20934-3-git-send-email-acme@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
So that we can filter by dso. Symbols in other dsos won't be
accounted for.
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Paul Mackerras <paulus@samba.org>
LKML-Reference: <1246399282-20934-2-git-send-email-acme@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
I.e. we can't handle these two kinds of files in the same way:
1) prelinked system library:
[acme@doppio pahole]$ readelf -s /usr/lib64/libdw-0.141.so | egrep 'FUNC.+GLOBAL.+dwfl_report_elf'
278: 00000030450105a0 261 FUNC GLOBAL DEFAULT 12 dwfl_report_elf@@ELFUTILS_0.122
2) not prelinked library with debug information from a -debuginfo package:
[acme@doppio pahole]$ readelf -s /usr/lib/debug/usr/lib64/libdw-0.141.so.debug | egrep 'FUNC.+GLOBAL.+dwfl_report_elf'
629: 00000000000105a0 261 FUNC GLOBAL DEFAULT 12 dwfl_report_elf
[acme@doppio pahole]$
Now the numbers I got for a pahole perf run are in line with
the numbers I get from oprofile.
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <20090630144317.GB12663@ghostprotocols.net>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This provides a way to mark a counter to be enabled on the next
exec. This is useful for measuring the total activity of a
program without including overhead from the process that
launches it.
This also changes the perf stat command to use this new
facility.
Signed-off-by: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <19017.43927.838745.689203@cargo.ozlabs.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Vince Weaver reported a 'perf stat' measurement overhead in the
count of retired instructions, which can amount to a +6000
instructions inflated count in the reported count.
At present, perf stat creates its counters on the perf process. Thus
the counters count the fork and various other activity in both the
parent and child, such as the resolver overhead for resolving PLT
entries for any libc functions that haven't been called before, such
as execvp.
This reduces the overhead by creating the counters on the child process
after the fork, using a couple of pipes to synchronize so that the
child process waits until the parent has created the counters before
doing the exec. To eliminate the PLT resolution overhead on calling
execvp, this does a dummy execvp first which will always fail.
With this, the overhead of executing a program goes down from over
4800 instructions to about 90 instructions on powerpc (32-bit).
This was measured with a statically-linked program written in
assembler which only does the 3 instructions needed to call _exit(0).
Before:
$ perf stat -e 0:1:u ./three
Performance counter stats for './three':
4858 instructions
0.001274523 seconds time elapsed
After:
$ perf stat -e 0:1:u ./three
Performance counter stats for './three':
92 instructions
0.000468153 seconds time elapsed
Reported-by: Vince Weaver <vince@deater.net>
Signed-off-by: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <19016.41425.814043.870352@cargo.ozlabs.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Peter expressed a strong preference for percentage based
display of scaled values - so revert to that from the
recently introduced multiplication-factor unit.
Reported-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Jaswinder Singh Rajput <jaswinder@kernel.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
The print out should read the value before changing the value.
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <4A487017.4090007@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Set attrs and nr_counters if no event is selected and !null_run.
Setting of attrs should depend on number of counters,
so we need to memcpy only for sizeof(default_attrs)
Also set nr_counters as ARRAY_SIZE(default_attrs) in place of
hardcoded value.
Signed-off-by: Jaswinder Singh Rajput <jaswinderrajput@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
LKML-Reference: <1246126749.32198.16.camel@hpdv5.satnam>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
In multi-run (-r/--repeat) printouts, print out the noise of
the wall-clock average as well.
Also, fix a bug in printing out scaled counters: if it was not
scaled then we should not update the average with -1.
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Allow a no-counters run. This can be useful to measure just
elapsed wall-clock time - or to assess the raw overhead of perf
stat itself, without running any counters.
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Vince Weaver reported that there's a handful of #ifdef __MINGW32__
sections in the code.
Remove them as they are in essence dead code - as unlike upstream
Git, the perf tool is unlikely to be ported to Windows.
Reported-by: Vince Weaver <vince@deater.net>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Complete the counter swap by indeed switching the times too and
updating the userpage after modifying the counter values.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
LKML-Reference: <1246014623.31755.195.camel@twins>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Use the newly created callchains radix tree to gather the chains stats
from the recorded events and then print the callchains for all of them,
sorted by hits, using the "-c" parameter with perf report.
Example:
66.15% [k] atm_clip_exit
63.08%
0xffffffffffffff80
0xffffffff810196a8
0xffffffff810c14c8
0xffffffff8101a79c
0xffffffff810194f3
0xffffffff8106ab7f
0xffffffff8106abe5
0xffffffff8106acde
0xffffffff8100d94b
0xffffffff8153e7ea
[...]
1.54%
0xffffffffffffff80
0xffffffff810196a8
0xffffffff810c14c8
0xffffffff8101a79c
[...]
Symbols are not yet resolved.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
LKML-Reference: <1246026481-8314-3-git-send-email-fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
We plan to display the callchains depending on some user-configurable
parameters.
To gather the callchains stats from the recorded stream in a fast way,
this patch introduces an ad hoc radix tree adapted for callchains and also
a rbtree to sort these callchains once we have gathered every events
from the stream.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
LKML-Reference: <1246026481-8314-2-git-send-email-fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Building latest perfcounter fails on the following error:
builtin-record.c: In function ‘create_counter’:
builtin-record.c:451: erreur: ignoring return value of ‘read’, declared with attribute warn_unused_result
make: *** [builtin-record.o] Erreur 1
Just check if we successfully read the perf file descriptor.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <1245961287-5327-1-git-send-email-fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Add 'l1d' and 'l1i' aliases again as shortcuts - just dont make them
the primary display alias.
Signed-off-by: Jaswinder Singh Rajput <jaswinderrajput@gmail.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
LKML-Reference: <1245945462.9157.11.camel@hpdv5.satnam>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Provide the basic infrastructure to provide per task stats.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Now that we can collect per task statistics, add modes that
make use of that facility.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
The PERF_EVENT_READ implementation made me realize we don't
actually need the sample_type int the output sample, since
we already have that in the perf_counter_attr information.
Therefore, remove the PERF_EVENT_MISC_OVERFLOW bit and the
event->type overloading, and imply put counter overflow
samples in a PERF_EVENT_SAMPLE type.
This also fixes the issue that event->type was only 32-bit
and sample_type had 64 usable bits.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
With the introduction of PERF_EVENT_READ we have the
possibility to provide accurate counter values for
individual tasks in a task hierarchy.
However, due to the lazy context switching used for similar
counter contexts our current per task counts are way off.
In order to maintain some of the lazy switch benefits we
don't disable it out-right, but simply iterate the active
counters and flip the values between the contexts.
This only reads the counters but does not need to reprogram
the full PMU.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Provide a read() like event which can be used to log the
counter value at specific sites such as child->parent
folding on exit.
In order to be useful, we log the counter parent ID, not the
actual counter ID, since userspace can only relate parent
IDs to perf_counter_attr constructs.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Update the mmap control page with the needed information to
use the userspace RDPMC instruction for self monitoring.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Add the needed time scale to the self-profile mmap information.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Since there are two distinct sections to the control page,
move them apart so that possible extentions don't overlap.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Create a structured file format that includes the full
perf_counter_attr and all its relevant counter IDs so that
the reporting program has full information.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Made new table for cache operartion stat 'hw_cache_stat' as:
L1I : Read and prefetch only
ITLB and BPU : Read-only
introduce is_cache_op_valid() for cache operation validity
And checks for valid cache operations.
Reported-by : Ingo Molnar <mingo@elte.hu>
Signed-off-by: Jaswinder Singh Rajput <jaswinderrajput@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
LKML-Reference: <1245930367.5308.33.camel@localhost.localdomain>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Looking backward for the first space from the end of a line in
/proc/pid/maps does not find the start of the pathname of the mapped
file if it contains a space.
Since the only slashes we have in this file occur in the (absolute!)
pathname column of file mappings, looking for the first slash in a
line is a safe method to find the name.
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Stefani Seibold <stefani@seibold.net>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <20090624190835.GA25548@cmpxchg.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Much of perf's libraries comes from the Git project. I noticed
that the files (in tools/perf/util/*.[ch] and elsewhere) are
quite spartan wrt. credits, so lets add a CREDITS file that
includes an (incomplete!) list of main contributors.
Thanks guys, these libraries are really useful. Special thanks
go to Johannes Schindelin and Junio C Hamano for coming up with
this list.
List-Composed-By: Johannes Schindelin <Johannes.Schindelin@gmx.de>
Cc: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Remove dead code and do some code alignment.
Signed-off-by: Jaswinder Singh Rajput <jaswinderrajput@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
LKML-Reference: <1245847774.2681.2.camel@ht.satnam>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Previous code made an assumption that the power on value of global
control MSR has enabled all fixed and general purpose counters properly.
However, this is not the case for certain Intel processors, such as
Atom - and it might also be firmware dependent.
Each enable bit in IA32_PERF_GLOBAL_CTRL is AND'ed with the
enable bits for all privilege levels in the respective IA32_PERFEVTSELx
or IA32_PERF_FIXED_CTR_CTRL MSRs to start/stop the counting of
respective counters. Counting is enabled if the AND'ed results is true;
counting is disabled when the result is false.
The end result is that all fixed counters are always disabled on Atom
processors because the assumption is just invalid.
Fix this by not initializing the ctrl-mask out of the global MSR,
but setting it to perf_counter_mask.
Reported-by: Stephane Eranian <eranian@googlemail.com>
Signed-off-by: Yong Wang <yong.y.wang@intel.com>
Cc: Arjan van de Ven <arjan@infradead.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
LKML-Reference: <20090624021324.GA2788@ywang-moblin2.bj.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
size_t res cannot be less than 0 - fread returns 0 on error.
[ Updated by: René Scharfe <rene.scharfe@lsrfire.ath.cx> ]
Reported-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Roel Kluin <roel.kluin@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Junio C Hamano <gitster@pobox.com>
LKML-Reference: <4A3FB479.2090902@lsrfire.ath.cx>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Error message should use stderr for verbose (-v), otherwise
message will be lost for:
$ ./perf stat -v <cmd> > /dev/null
For example on AMD bus-cycles event is not available so now
it looks like:
$ ./perf stat -v -e bus-cycles ls > /dev/null
Error: counter 0, sys_perf_counter_open() syscall returned with -1 (Invalid argument)
Performance counter stats for 'ls':
<not counted> bus-cycles
0.006765877 seconds time elapsed.
Signed-off-by: Jaswinder Singh Rajput <jaswinderrajput@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
LKML-Reference: <1245757369.3776.1.camel@localhost.localdomain>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
We don't need to add usage counts for swcounter and attr usage
models for inherited counters since the parent counter will
always have one, which suffices to generate the needed output.
This avoids up to 3 global atomic increments per inherited
counter.
LKML-Reference: <new-submission>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Teach perf_counter_alloc() about inheritance so that we can
optimize the inherit path in the next patch.
Remove the child_counter->atrr.inherit = 1 line because the
only way to get there is if parent_counter->attr.inherit == 1
and we copy the attrs.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Similar to tracepoints, use an enable variable to reduce
overhead when unused.
Only look for a counter of a particular event type when we know
there is at least one in the system.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <new-submission>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Martin Schwidefsky reported "perf report" symbol resolution
problems on S390.
Since we only report MMAP, not MUNMAP, we have to deal with
overlapping maps.
We used to simply throw out the old map on the assumption whole
maps got unmapped. This obviously doesn't deal with partial
unmaps. However it appears some dynamic linkers do fancy
partial unmaps (s390), so do something more elaborate and
truncate the old maps, only removing them when they've been
fully covered.
This resolves (part of) the S390 symbol resolution problems.
Reported-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Tested-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
-l is not supported, it should be -S for scale.
Signed-off-by: Jaswinder Singh Rajput <jaswinderrajput@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
LKML-Reference: <1245703959.6167.16.camel@localhost.localdomain>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
"faults" should be alias for "page-faults"
Also fixed alignment and 80 characters issue
Signed-off-by: Jaswinder Singh Rajput <jaswinderrajput@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
LKML-Reference: <1245683846.12092.1.camel@localhost.localdomain>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Print more symbol relocation related info under -vv.
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
By introducing alias member in event_symbol :
1. duplicate lines are removed, like:
cpu-cycles and cycles
branch-instructions and branches
context-switches and cs
cpu-migrations and migrations
2. We can also add alias for another events.
Now ./perf list looks like :
List of pre-defined events (to be used in -e):
cpu-cycles OR cycles [Hardware event]
instructions [Hardware event]
cache-references [Hardware event]
cache-misses [Hardware event]
branch-instructions OR branches [Hardware event]
branch-misses [Hardware event]
bus-cycles [Hardware event]
cpu-clock [Software event]
task-clock [Software event]
page-faults [Software event]
faults [Software event]
minor-faults [Software event]
major-faults [Software event]
context-switches OR cs [Software event]
cpu-migrations OR migrations [Software event]
rNNN [raw hardware event descriptor]
Signed-off-by: Jaswinder Singh Rajput <jaswinderrajput@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
LKML-Reference: <1245669268.17153.8.camel@localhost.localdomain>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Define separate declarations for H/W and S/W events to:
1. Shorten name to save some space so that we can add more members
2. Fix alignment
3. Avoid declaring HARDWARE/SOFTWARE again and again.
Removed unused CR(x, y)
Signed-off-by: Jaswinder Singh Rajput <jaswinderrajput@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
LKML-Reference: <1245669194.17153.6.camel@localhost.localdomain>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Lucas De Marchi reported that perf report and perf annotate
displays mismatching profile if a perf.data is analyzed on
an older kernel - even if the correct vmlinux is specified
via the -k option.
The reason is the fallback path in util/symbol.c:dso__load_kernel():
int dso__load_kernel(struct dso *self, const char *vmlinux,
symbol_filter_t filter, int verbose)
{
int err = -1;
if (vmlinux)
err = dso__load_vmlinux(self, vmlinux, filter, verbose);
if (err)
err = dso__load_kallsyms(self, filter, verbose);
return err;
}
dso__load_vmlinux() returns negative on error, but on success it
returns the number of symbols loaded - which confuses the function
to load the kallsyms.
This is normally harmless, as reporting is usually performed on the
same kernel that is analyzed - but if there's a mismatch then we
load the wrong kallsyms and create a non-sensical symbol tree.
The fix is to only fall back to kallsyms on errors.
Reported-by: Lucas De Marchi <lucas.de.marchi@gmail.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
