On 8/2/21 10:44 AM, Gang Li wrote:
On 7/31/21 4:03 AM, Steven Rostedt wrote:
Yes, synthetic events are just like normal events, and have triggers,
stack traces, and do pretty much anything that another event can do.
I'm just finishing up a libtracfs called tracefs_sql() (hopefully
posting it today), that allows you to create a synthetic event via an
SQL statement. But I don't think this is what you are looking for.
What about using function tracing? Because the tracepoint is called
from __mmap_lock* helper functions that function tracer can see, you
can just do the following:
# trace-cmd start -e mmap_lock -p function -l '__mmap_lock_*'
# trace-cmd show
[..]
trace-cmd-1840 [006] .... 194.576801:
__mmap_lock_do_trace_start_locking <-do_user_addr_fault
trace-cmd-1840 [006] ...1 194.576805:
mmap_lock_start_locking: mm=000000006515cb1f
memcg_path=/user.slice/user-0.slice/session-2.scope write=false
Hi!
I find that sometimes the output data is out of order, which leads to
inaccurate time stamps and make it hard to analyse.
node-953 [001] .... 203.823297:
__mmap_lock_do_trace_start_locking <-do_user_addr_fault
node-955 [002] .... 203.823297:
__mmap_lock_do_trace_start_locking <-do_user_addr_fault
node-956 [003] .... 203.823297:
__mmap_lock_do_trace_start_locking <-do_user_addr_fault
node-953 [001] .... 203.823297:
mmap_lock_start_locking: mm=000000004395a005
memcg_path=/user.slice/user-0.slice/session-1.scope write=false
ip=do_user_addr_fault+0x270/0x4d0
node-953 [001] .... 203.823298:
__mmap_lock_do_trace_acquire_returned <-do_user_addr_fault
Is there any other way to collect ip in each event? It seems that adding
"ip" fields is the only way to do this accurately and effectively.
