Now that we can filter based on fields via perf record, people
will start using filter expressions and will expect them to
be obvious.
The primary way to see which fields are available is by looking
at the trace output, such as:
gcc-18676 [000] 343.011728: irq_handler_entry: irq=0 handler=timer
cc1-18677 [000] 343.012727: irq_handler_entry: irq=0 handler=timer
cc1-18677 [000] 343.032692: irq_handler_entry: irq=0 handler=timer
cc1-18677 [000] 343.033690: irq_handler_entry: irq=0 handler=timer
cc1-18677 [000] 343.034687: irq_handler_entry: irq=0 handler=timer
cc1-18677 [000] 343.035686: irq_handler_entry: irq=0 handler=timer
cc1-18677 [000] 343.036684: irq_handler_entry: irq=0 handler=timer
While 'irq==0' filters work, the 'handler==<x>' filter expression
does not work:
$ perf record -R -f -a -e irq:irq_handler_entry --filter handler=timer sleep 1
Error: failed to set filter with 22 (Invalid argument)
The problem is that while an 'irq' field exists and is recognized
as a filter field - 'handler' does not exist - its name is 'name'
in the output.
To solve this, we need to synchronize the printout and the field
names, wherever possible.
In cases where the printout prints a non-field, we enclose
that information in square brackets, such as:
perf-1380 [013] 724.903505: softirq_exit: vec=9 [action=RCU]
perf-1380 [013] 724.904482: softirq_exit: vec=1 [action=TIMER]
This way users can use filter expressions more intuitively: all
fields that show up as 'primary' (non-bracketed) information is
filterable.
This patch harmonizes the field names for all irq, bkl, power,
sched and timer events.
We might in fact think about dropping the print format bit of
generic tracepoints altogether, and just print the fields that
are being recorded.
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Tom Zanussi <tzanussi@gmail.com>
Cc: 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: Arnaldo Carvalho de Melo <acme@redhat.com>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Add two events lock_kernel and unlock_kernel() to trace the bkl uses.
This opens the door for userspace tools to perform statistics about
the callsites that use it, dependencies with other locks (by pairing
the trace with lock events), use with recursivity and so on...
The {__reacquire,release}_kernel_lock() events are not traced because
these are called from schedule, thus the sched events are sufficient
to trace them.
Example of a trace:
hald-addon-stor-4152 [000] 165.875501: unlock_kernel: depth: 0, fs/block_dev.c:1358 __blkdev_put()
hald-addon-stor-4152 [000] 167.832974: lock_kernel: depth: 0, fs/block_dev.c:1167 __blkdev_get()
How to get the callsites that acquire it recursively:
cd /debug/tracing/events/bkl
echo "lock_depth > 0" > filter
firefox-4951 [001] 206.276967: unlock_kernel: depth: 1, fs/reiserfs/super.c:575 reiserfs_dirty_inode()
You can also filter by file and/or line.
v2: Use of FILTER_PTR_STRING attribute for files and lines fields to
make them traceable.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Ingo Molnar