Commit Graph

8 Commits

Author SHA1 Message Date
Namhyung Kim c9add62195 trace: Try using tracefs first
Recent Linux kernel provides separate tracefs which doesn't need to be
mounted on the debugfs.  Although most systems mount it at the
traditional place on the debugfs, it'd be safer to check tracefs first.

Signed-off-by: Namhyung Kim <namhyung@gmail.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2017-12-18 14:37:36 +00:00
Namhyung Kim babfff8e11 trace: Generalize searching for debugfs
The find_debugfs() can be shared to find a different filesystem like
tracefs.  So make it more general and rename to find_mount().

Signed-off-by: Namhyung Kim <namhyung@gmail.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2017-12-18 14:37:36 +00:00
Namhyung Kim 5070570c90 trace: Simplify find_debugfs()
The return vale of find_debugfs() is 1 if it could find a mount point of
debugfs.  It can be saved in the while loop instead of checking it again.

Signed-off-by: Namhyung Kim <namhyung@gmail.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2017-12-18 14:37:36 +00:00
Daniel P. Berrange 0ab8ed18a6 trace: switch to modular code generation for sub-directories
Introduce rules in the top level Makefile that are able to generate
trace.[ch] files in every subdirectory which has a trace-events file.

The top level directory is handled specially, so instead of creating
trace.h, it creates trace-root.h. This allows sub-directories to
include the top level trace-root.h file, without ambiguity wrt to
the trace.g file in the current sub-dir.

Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Message-id: 20170125161417.31949-7-berrange@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2017-01-31 17:11:18 +00:00
Daniel P. Berrange 8ed5372874 trace: don't abort qemu if ftrace can't be initialized
If the ftrace backend is compiled into QEMU, any attempt
to start QEMU while non-root will fail due to the
inability to open /sys/kernel/debug/tracing/tracing_on.

Add a fallback into the code so that it connects up the
trace_marker_fd variable to /dev/null when getting
EACCES on the 'trace_on' file. This allows QEMU to
run, with ftrace turned into a no-op.

[Fixed s/setting/getting/ and s/EACCESS/EACCES/ errors pointed out by
Eric Blake <eblake@redhat.com>.
--Stefan]

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Message-id: 1475588159-30598-13-git-send-email-berrange@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2016-10-12 09:35:54 +02:00
Peter Maydell d38ea87ac5 all: Clean up includes
Clean up includes so that osdep.h is included first and headers
which it implies are not included manually.

This commit was created with scripts/clean-includes.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Message-id: 1454089805-5470-16-git-send-email-peter.maydell@linaro.org
2016-02-04 17:41:30 +00:00
Lluís Vilanova 5b808275f3 trace: Multi-backend tracing
Adds support to compile QEMU with multiple tracing backends at the same time.

For example, you can compile QEMU with:

  $ ./configure --enable-trace-backends=ftrace,dtrace

Where 'ftrace' can be handy for having an in-flight record of events, and 'dtrace' can be later used to extract more information from the system.

This patch allows having both available without recompiling QEMU.

Signed-off-by: Lluís Vilanova <vilanova@ac.upc.edu>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2014-06-09 15:43:40 +02:00
Eiichi Tsukata 781e9545db trace: Add ftrace tracing backend
This patch adds a ftrace tracing backend which sends trace event to
ftrace marker file. You can effectively compare qemu trace data and
kernel(especially, kvm.ko when using KVM) trace data.
The ftrace backend is restricted to Linux only.

To try out the ftrace backend:

 $ ./configure --trace-backend=ftrace
 $ make

if you use KVM, enable kvm events in ftrace:

 # sudo echo 1 > /sys/kernel/debug/tracing/events/kvm/enable

After running qemu by root user, you can get the trace:

 # cat /sys/kernel/debug/tracing/trace

Signed-off-by: Eiichi Tsukata <eiichi.tsukata.xh@hitachi.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2013-05-03 13:58:09 +02:00