On Sat, Jan 14, 2023 at 11:58:41AM +1300, Paulo Miguel Almeida wrote: > In tracecmd/trace-record.c:<run_cmd>, trace-cmd record -F <executable> > is launched via the libc's execvp() routine. The way that execvp() routine > works is by invoking execve syscall for every entry on the $PATH if > command specified is neither absolute nor relative which can come across > as a bit cryptic to untrained eyes. > > - absolute path example: > > # trace-cmd record -p function_graph \ > -g __x64_sys_execve -O nofuncgraph-irqs \ > -n __cond_resched --max-graph-depth 1 \ > -F /usr/bin/echo "ftrace" > /dev/null > > # trace-cmd report > echo-172994 [000] 185539.798539: funcgraph_entry: ! 803.376 us | __x64_sys_execve(); > > - PATH-dependent path example: > > # trace-cmd record -p function_graph \ > -g __x64_sys_execve -O nofuncgraph-irqs \ > -n __cond_resched --max-graph-depth 1 \ > -F echo "ftrace" > /dev/null > > # trace-cmd report > echo-172656 [002] 185009.671586: funcgraph_entry: ! 288.732 us | __x64_sys_execve(); > echo-172656 [002] 185009.671879: funcgraph_entry: ! 158.337 us | __x64_sys_execve(); > echo-172656 [002] 185009.672042: funcgraph_entry: ! 161.843 us | __x64_sys_execve(); > echo-172656 [002] 185009.672207: funcgraph_entry: ! 157.656 us | __x64_sys_execve(); > echo-172656 [002] 185009.672369: funcgraph_entry: ! 156.343 us | __x64_sys_execve(); > echo-172656 [002] 185009.672529: funcgraph_entry: ! 863.629 us | __x64_sys_execve(); > > Open code the libc's execvp routine into trace-cmd so ftrace will only > start recording once the command is found when it needs to be found in > PATH. > > Signed-off-by: Paulo Miguel Almeida <paulo.miguel.almeida.rodenas@xxxxxxxxx> > --- > Changelog: > > - v2: open code execvp routine into trace-cmd. (Req. Steve Rostedt) > - v1: https://lore.kernel.org/linux-trace-devel/Y7dUo6woh9Y31cdl@xxxxxxxxxxxxxxx/ > --- Ignore this patch. I just realised that I didn't tweak the CUnit tests. I will submit another patch shortly. - Paulo A.
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