On Thu, 17 Apr 2014 08:08:08 +1000 Dave Chinner <david@xxxxxxxxxxxxx> wrote: > > Here's the "best" I've come up with so far... > > > > # for FUNCTION in `grep "t xfs_" /proc/kallsyms | awk '{print $3}'`; do echo "r:ret_$FUNCTION $FUNCTION \$retval" >> /sys/kernel/debug/tracing/kprobe_events; done BTW, it's usually better to do: grep 't xfs_' /proc/kallsyms | awk '{print $3}' ; while read FUNCTION; do .... > > > > # for ENABLE in /sys/kernel/debug/tracing/events/kprobes/ret_xfs_*/enable; do echo 1 > $ENABLE; done > > > > run a test that fails: > > > > # dd if=/dev/zero of=newfile bs=513 oflag=direct > > dd: writing `newfile': Invalid argument > > > > # for ENABLE in /sys/kernel/debug/tracing/events/kprobes/ret_xfs_*/enable; do echo 0 > $ENABLE; done > > > > # cat /sys/kernel/debug/tracing/trace > > <snip> > > <...>-63791 [000] d... 705435.568913: ret_xfs_vn_mknod: (xfs_vn_create+0x13/0x20 [xfs] <- xfs_vn_mknod) arg1=0 > > <...>-63791 [000] d... 705435.568913: ret_xfs_vn_create: (vfs_create+0xdb/0x100 <- xfs_vn_create) arg1=0 > > <...>-63791 [000] d... 705435.568918: ret_xfs_file_open: (do_dentry_open+0x24e/0x2e0 <- xfs_file_open) arg1=0 > > <...>-63791 [000] d... 705435.568934: ret_xfs_file_dio_aio_write: (xfs_file_aio_write+0x147/0x150 [xfs] <- xfs_file_dio_aio_write) arg1=ffffffffffffffea > > > > Hey look, it's "-22" in hex! ;) > > > > so it's possible, but bleah. > > Steve, we want to be able to trap specific return codes from > functions. Say, for example, the first function that returns > EINVAL/-EINVAL in XFS under a given workload. > > What's the most efficient way to do that with ftrace? > > And can that be set up as a trigger so we can use it to dump a > snapshot of the last N events into the trace buffer or do other > interesting things with that event? Well, after you do the above, you could also do a while loop to all those events and update the filter: echo 'arg1 > 0xffffffffffffff00' > /debug/tracing/events/kprobes/filter Which would trace only those functions that had an error code (assuming the error code is less than 256). You could also use the trigger files: echo 'traceoff if arg1 > 0xffffffffffffff00' > /debug/tracing/events/kprobes/*/trigger The above wont actually work as is, you would need to do another while loop of trigger files and set them each individually. -- Steve _______________________________________________ xfs mailing list xfs@xxxxxxxxxxx http://oss.sgi.com/mailman/listinfo/xfs