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author | Linus Torvalds <torvalds@linux-foundation.org> | 2015-04-14 10:49:03 -0700 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2015-04-14 10:49:03 -0700 |
commit | eeee78cf77df0450ca285a7cd6d73842181e825c (patch) | |
tree | 330540323eae82977756e5086492654b9e461871 /kernel/trace/Kconfig | |
parent | 3f3c73de77b5598e9f87812ac4da9445090c3b4a (diff) | |
parent | 9828413d4715d4ed12bc92b161f4ed377d777ffb (diff) |
Merge tag 'trace-v4.1' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace
Pull tracing updates from Steven Rostedt:
"Some clean ups and small fixes, but the biggest change is the addition
of the TRACE_DEFINE_ENUM() macro that can be used by tracepoints.
Tracepoints have helper functions for the TP_printk() called
__print_symbolic() and __print_flags() that lets a numeric number be
displayed as a a human comprehensible text. What is placed in the
TP_printk() is also shown in the tracepoint format file such that user
space tools like perf and trace-cmd can parse the binary data and
express the values too. Unfortunately, the way the TRACE_EVENT()
macro works, anything placed in the TP_printk() will be shown pretty
much exactly as is. The problem arises when enums are used. That's
because unlike macros, enums will not be changed into their values by
the C pre-processor. Thus, the enum string is exported to the format
file, and this makes it useless for user space tools.
The TRACE_DEFINE_ENUM() solves this by converting the enum strings in
the TP_printk() format into their number, and that is what is shown to
user space. For example, the tracepoint tlb_flush currently has this
in its format file:
__print_symbolic(REC->reason,
{ TLB_FLUSH_ON_TASK_SWITCH, "flush on task switch" },
{ TLB_REMOTE_SHOOTDOWN, "remote shootdown" },
{ TLB_LOCAL_SHOOTDOWN, "local shootdown" },
{ TLB_LOCAL_MM_SHOOTDOWN, "local mm shootdown" })
After adding:
TRACE_DEFINE_ENUM(TLB_FLUSH_ON_TASK_SWITCH);
TRACE_DEFINE_ENUM(TLB_REMOTE_SHOOTDOWN);
TRACE_DEFINE_ENUM(TLB_LOCAL_SHOOTDOWN);
TRACE_DEFINE_ENUM(TLB_LOCAL_MM_SHOOTDOWN);
Its format file will contain this:
__print_symbolic(REC->reason,
{ 0, "flush on task switch" },
{ 1, "remote shootdown" },
{ 2, "local shootdown" },
{ 3, "local mm shootdown" })"
* tag 'trace-v4.1' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: (27 commits)
tracing: Add enum_map file to show enums that have been mapped
writeback: Export enums used by tracepoint to user space
v4l: Export enums used by tracepoints to user space
SUNRPC: Export enums in tracepoints to user space
mm: tracing: Export enums in tracepoints to user space
irq/tracing: Export enums in tracepoints to user space
f2fs: Export the enums in the tracepoints to userspace
net/9p/tracing: Export enums in tracepoints to userspace
x86/tlb/trace: Export enums in used by tlb_flush tracepoint
tracing/samples: Update the trace-event-sample.h with TRACE_DEFINE_ENUM()
tracing: Allow for modules to convert their enums to values
tracing: Add TRACE_DEFINE_ENUM() macro to map enums to their values
tracing: Update trace-event-sample with TRACE_SYSTEM_VAR documentation
tracing: Give system name a pointer
brcmsmac: Move each system tracepoints to their own header
iwlwifi: Move each system tracepoints to their own header
mac80211: Move message tracepoints to their own header
tracing: Add TRACE_SYSTEM_VAR to xhci-hcd
tracing: Add TRACE_SYSTEM_VAR to kvm-s390
tracing: Add TRACE_SYSTEM_VAR to intel-sst
...
Diffstat (limited to 'kernel/trace/Kconfig')
-rw-r--r-- | kernel/trace/Kconfig | 28 |
1 files changed, 28 insertions, 0 deletions
diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig index a5da09c899dd..fedbdd7d5d1e 100644 --- a/kernel/trace/Kconfig +++ b/kernel/trace/Kconfig @@ -599,6 +599,34 @@ config RING_BUFFER_STARTUP_TEST If unsure, say N +config TRACE_ENUM_MAP_FILE + bool "Show enum mappings for trace events" + depends on TRACING + help + The "print fmt" of the trace events will show the enum names instead + of their values. This can cause problems for user space tools that + use this string to parse the raw data as user space does not know + how to convert the string to its value. + + To fix this, there's a special macro in the kernel that can be used + to convert the enum into its value. If this macro is used, then the + print fmt strings will have the enums converted to their values. + + If something does not get converted properly, this option can be + used to show what enums the kernel tried to convert. + + This option is for debugging the enum conversions. A file is created + in the tracing directory called "enum_map" that will show the enum + names matched with their values and what trace event system they + belong too. + + Normally, the mapping of the strings to values will be freed after + boot up or module load. With this option, they will not be freed, as + they are needed for the "enum_map" file. Enabling this option will + increase the memory footprint of the running kernel. + + If unsure, say N + endif # FTRACE endif # TRACING_SUPPORT |