[ltt-dev] Tracing syscall_entry not working

[Alexandre Montplaisir]

On 11-10-05 01:09 PM, Venkatesh Babu Chitlur Srinivasa (vchitlur) wrote:
> I followed the instructions in 
> http://git.lttng.org/?p=lttv.git;a=blob_plain;f=LTTngManual.html#install
> lttng to enable the tracing for only the system call enter/exits on
> MontaVista kernel. So I loaded only the  ltt-* modules and
> syscall-trace.
>
> I did mount debugfs and enabled only syscall enter/exit.
>
> echo 1 > /mnt/debugfs/ltt/markers/kernel/syscall_entry/enable
> echo 1 > /mnt/debugfs/ltt/markers/kernel/syscall_exit/enable
>
> lttctl -C -w /tmp/trace1 trace1 trace1
>
> lttctl -D trace1
>
> lttv -mtextDump -t /tmp/trace1
>
> But it is only tracing the syscall exits but not syscall enter.
>
> kernel.syscall_exit: 0.991063935 (/tmp/trace1/kernel_3), 0, 0, , , 0,
> 0x0, MODE_UNKNOWN { ret = 0 }
> kernel.syscall_exit: 0.991065411 (/tmp/trace1/kernel_3), 0, 0, , , 0,
> 0x0, MODE_UNKNOWN { ret = 1 }
> kernel.syscall_exit: 0.991066830 (/tmp/trace1/kernel_3), 0, 0, , , 0,
> 0x0, MODE_UNKNOWN { ret = 2 }
> kernel.syscall_exit: 0.991068682 (/tmp/trace1/kernel_3), 0, 0, , , 0,
> 0x0, MODE_UNKNOWN { ret = 0 }
> kernel.syscall_exit: 0.991203430 (/tmp/trace1/kernel_3), 0, 0, , , 0,
> 0x0, MODE_UNKNOWN { ret = 718741504 }
> kernel.syscall_exit: 0.991255070 (/tmp/trace1/kernel_3), 0, 0, , , 0,
> 0x0, MODE_UNKNOWN { ret = 0 }
> kernel.syscall_exit: 0.991300875 (/tmp/trace1/kernel_3), 0, 0, , , 0,
> 0x0, MODE_UNKNOWN { ret = 8060 }
> kernel.syscall_exit: 0.991322296 (/tmp/trace1/kernel_2), 0, 0, , , 0,
> 0x0, MODE_UNKNOWN { ret = 0 }
>
> Even when I loaded the all the other trace modules and did ltt-armall,
> still I am seeing the traces for only syscall_exit but not for
> syscall_enter. Am I missing something here?

Just out of curiosity, are you grep'ing to get this output? The event
name is syscall_entry, not _enter, so grep obviously wouldn't find anything.

-- 
Alexandre Montplaisir
DORSAL lab,
École Polytechnique de Montréal