In section 2.1.3 (http://sourceware.org/systemtap/SystemTap_Beginners_Guide/using-systemtap.html#testing), it says to try: stap -v -e 'probe vfs.read {printf("read performed\n"); exit()}' This doesn't work, giving the error: root@quimby:~/stp# stap -v -e 'probe vfs.read {printf("read\n"); exit()}' Pass 1: parsed user script and 38 library script(s) in 120usr/0sys/129real ms. semantic error: probe point mismatch at position 1 (alternatives: __set_page_dirty_buffers add_to_page_cache block_sync_page buffer_migrate_page do_mpage_readpage do_sync_read do_sync_write remove_from_page_cache) while resolving probe point vfs.read Pass 2: analyzed script: 0 probe(s), 0 function(s), 0 embed(s), 0 global(s) in 0usr/0sys/2real ms. Pass 2: analysis failed. Try again with more '-v' (verbose) options.
Can you check whether you have your kernel debuginfo installed? The stap-report script may generate useful data for us too.
(In reply to comment #0) > In section 2.1.3 > (http://sourceware.org/systemtap/SystemTap_Beginners_Guide/using-systemtap.html#testing), > it says to try: > > stap -v -e 'probe vfs.read {printf("read performed\n"); exit()}' > > This doesn't work... Can you try the following? 'vfs.read' maps to 'kernel.function("vfs_read")' # stap -v -e 'probe kernel.function("vfs_read") {printf("read performed\n"); exit()}' Also, as Frank mentioned, the output of 'stap-report' will be helpful.
Looking into it in a bit more depth, I can probe vfs.read on my Fedora box at home, but it fails on the Ubuntu box I have to use at work. Probing on the kernel vfs_read() directly works. The Ubuntu vfs.stp is significantly shorter than the Fedora one, and in particular, lacks the probes for vfs.{read,write} So the simple question is, can I just copy over the updated vfs tapset? The work server is Ubuntu 8.04 and comes with a relatively archaic systemtap-0.0.20071201-1. Is there anything in the newer tapsets that would fail to work with a systemtap that old? (Incidentally, stap-report isn't present either)
(In reply to comment #3) > So the simple question is, can I just copy over the updated vfs tapset? > The work server is Ubuntu 8.04 and comes with a relatively archaic > systemtap-0.0.20071201-1. Is there anything in the newer tapsets that > would fail to work with a systemtap that old? The new tapset file might but more likely won't work with >2-year-old stap. Please try building a new version.
Since this bug has been "waiting" for over three years, and current versions of systemtap work correctly here, I'm closing this one.