SystemTap provides a "semaphore" that can optionally be tested before
executing a trace event. The purpose of this mechanism is to skip
expensive tracing code when the trace event is disabled.
For example, some applications may have trace events that format or
convert strings for trace events. This expensive processing should only
be done in the case where the trace event is enabled.
Since QEMU's generated trace events never have such special-purpose
code, there is no reason to add the semaphore check.
Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Adds a 'TRACE_${NAME}_ENABLED' preprocessor define for each tracing event in
"trace.h".
This lets the user conditionally compile code with a relatively high execution
cost that is only necessary when producing the tracing information for an event
that is enabled.
Note that events using this define will probably have the "disable" property by
default, in order to avoid such costs on regular builds.
Signed-off-by: Lluís Vilanova <vilanova@ac.upc.edu>
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
The tracetool parser only picks up PRI*64 and other format string macros
when enclosed between double quoted strings. Lift this restriction by
extracting everything after the closing ')' as the format string:
cpu_set_apic_base(uint64_t val) "%016"PRIx64
^^ ^^
One trick here: it turns out that backslashes in the format string like
"\n" were being interpreted by echo(1). Fix this by using the POSIX
printf(1) command instead. Although it normally does not make sense to
include backslashes in trace event format strings, an injected newline
causes tracetool to emit a broken header file and I want to eliminate
cases where broken output is emitted, even if the input was bad.
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
Uses the generic interface provided in "trace/control.h" in order to provide
a programmatic interface as well as command line and monitor controls.
Signed-off-by: Fabien Chouteau <chouteau@adacore.com>
Signed-off-by: Lluís Vilanova <vilanova@ac.upc.edu>
Note that this refers to the backend-specific state (whether the output must be
generated), not the event "disabled" property (which always uses the "nop"
backend).
Signed-off-by: Lluís Vilanova <vilanova@ac.upc.edu>
Any event with the keyword/property "disable" generates an empty trace event
using the "nop" backend, regardless of the current backend.
Signed-off-by: Lluís Vilanova <vilanova@ac.upc.edu>
This adds/modifies the following functions:
* get_name: Get _only_ the event name
* has_property: Return whether an event has a property (keyword before the event
name)
Signed-off-by: Lluís Vilanova <vilanova@ac.upc.edu>
Be greedy in matching the trailing "\)*" pattern. Otherwise, all the
text in the trace string up to the last closed parenthesis is taken as
part of the prototype.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Optional feature allowing a user to generate the probe list to match
the name of the binary, in case they wish to install qemu under a
different name than qemu-{system,user},<arch>
Signed-off-by: Jes Sorensen <Jes.Sorensen@redhat.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Acked-by: Stefan Hajnoczi <stefaha@linux.vnet.ibm.com>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
This backend sends trace events to standard error output during the emulation.
Also add a "--list-backends" option to tracetool, so configure script can
display the list of available backends.
Signed-off-by: Fabien Chouteau <chouteau@adacore.com>
Acked-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
