On 19.01.2018 20:15, David Sterba wrote: > On Fri, Jan 05, 2018 at 12:51:16PM -0700, Liu Bo wrote: >> This is adding a tracepoint 'btrfs_handle_em_exist' to help debug the >> subtle bugs around merge_extent_mapping. >> >> Signed-off-by: Liu Bo <bo.li....@oracle.com> > > Nikolay has some concernas about adding the tracepoint, so I'll leave > this patch out of the series for now as we should decide how to proceed. > > Thacepoints are considered an ABI by some and not ABI by others. I think > it's a good addition to the debugging aids that also may turn out to be > useful for evaluating performance later. > > At minimum we could add some prefix/suffix to the debugging tracepoint > name, so we can let developers add what they need right away. >
My concern specifically has to do with the fact that if tracepoints are considere ABI then whatever decision we make now will be cast in stone and if we juggle the code around we will still have to retain the format of the tracepoint. If, OTOH we are able to remove and change the tracepoint as we see fit - then it's okay. Otherwise we risk polluting the code -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
