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With the rework of how the __string() handles dynamic strings where it
saves off the source string in field in the helper structure[1], the
assignment of that value to the trace event field is stored in the helper
value and does not need to be passed in again.
This means that with:
__string(field, mystring)
Which use to be assigned with __assign_str(field, mystring), no longer
needs the second parameter and it is unused. With this, __assign_str()
will now only get a single parameter.
There's over 700 users of __assign_str() and because coccinelle does not
handle the TRACE_EVENT() macro I ended up using the following sed script:
git grep -l __assign_str | while read a ; do
sed -e 's/\(__assign_str([^,]*[^ ,]\) *,[^;]*/\1)/' $a > /tmp/test-file;
mv /tmp/test-file $a;
done
I then searched for __assign_str() that did not end with ';' as those
were multi line assignments that the sed script above would fail to catch.
Note, the same updates will need to be done for:
__assign_str_len()
__assign_rel_str()
__assign_rel_str_len()
I tested this with both an allmodconfig and an allyesconfig (build only for both).
[1] https://lore.kernel.org/linux-trace-kernel/[email protected]/
Link: https://lore.kernel.org/linux-trace-kernel/[email protected]
Cc: Masami Hiramatsu <[email protected]>
Cc: Mathieu Desnoyers <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Julia Lawall <[email protected]>
Signed-off-by: Steven Rostedt (Google) <[email protected]>
Acked-by: Jani Nikula <[email protected]>
Acked-by: Christian König <[email protected]> for the amdgpu parts.
Acked-by: Thomas Hellström <[email protected]> #for
Acked-by: Rafael J. Wysocki <[email protected]> # for thermal
Acked-by: Takashi Iwai <[email protected]>
Acked-by: Darrick J. Wong <[email protected]> # xfs
Tested-by: Guenter Roeck <[email protected]>
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By using DECLARE_EVENT_CLASS and TRACE_EVENT_FN, we can save a lot of
space from duplicate code.
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Gang Li <[email protected]>
Acked-by: Vlastimil Babka <[email protected]>
Reviewed-by: Steven Rostedt (VMware) <[email protected]>
Cc: Axel Rasmussen <[email protected]>
Cc: Ingo Molnar <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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Ftrace core will add newline automatically on printing, so using it in
TP_printkcreates a blank line.
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Gang Li <[email protected]>
Acked-by: Vlastimil Babka <[email protected]>
Reviewed-by: Steven Rostedt (VMware) <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Axel Rasmussen <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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The goal of these tracepoints is to be able to debug lock contention
issues. This lock is acquired on most (all?) mmap / munmap / page fault
operations, so a multi-threaded process which does a lot of these can
experience significant contention.
We trace just before we start acquisition, when the acquisition returns
(whether it succeeded or not), and when the lock is released (or
downgraded). The events are broken out by lock type (read / write).
The events are also broken out by memcg path. For container-based
workloads, users often think of several processes in a memcg as a single
logical "task", so collecting statistics at this level is useful.
The end goal is to get latency information. This isn't directly included
in the trace events. Instead, users are expected to compute the time
between "start locking" and "acquire returned", using e.g. synthetic
events or BPF. The benefit we get from this is simpler code.
Because we use tracepoint_enabled() to decide whether or not to trace,
this patch has effectively no overhead unless tracepoints are enabled at
runtime. If tracepoints are enabled, there is a performance impact, but
how much depends on exactly what e.g. the BPF program does.
[[email protected]: fix use-after-free race and css ref leak in tracepoints]
Link: https://lkml.kernel.org/r/[email protected]
[[email protected]: v3]
Link: https://lkml.kernel.org/r/[email protected]
[[email protected]: in-depth examples of tracepoint_enabled() usage, and per-cpu-per-context buffer design]
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Axel Rasmussen <[email protected]>
Acked-by: Vlastimil Babka <[email protected]>
Cc: Steven Rostedt <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Michel Lespinasse <[email protected]>
Cc: Daniel Jordan <[email protected]>
Cc: Jann Horn <[email protected]>
Cc: Chinwen Chang <[email protected]>
Cc: Davidlohr Bueso <[email protected]>
Cc: David Rientjes <[email protected]>
Cc: Laurent Dufour <[email protected]>
Cc: Yafang Shao <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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