The following two patches (kernel + application) would allow one to annotate parts of the blktrace stream w/ simple messages. I've included a sample one for elevator switches: 8,16 1 813055 20.259000000 4692 I R 3088320 + 8 [dd] 8,16 1 813056 20.259000000 4692 Q R 3088328 + 8 [dd] 8,16 1 20.259000000 0 m N elv switch: deadline 8,16 1 813057 20.259000000 4692 G R 3088328 + 8 [dd] 8,16 1 813058 20.259000000 4692 I R 3088328 + 8 [dd] These patches are a bit rough (but compile, and appear to work ok so far). In particular, I'd break the kernel patch into a blktrace addition and an elevator switch addition, plus the application patch would need documentation updates. My nefarious ultimate goal would be to add in the ability for user-level insertions for (e.g.): 1. Start blktrace 2. Do some stuff... 3. Insert a tag "switching to other stuff" 4. Do other stuff 5. Insert a tag "switching to yet other stuff" 6. Do yet other stuff This way you could study different parts of the resultant traces using the tags to separate them time-wise. [For now, I'd just switch schedulers back and forth to see the separators.) Looking for comments (hence the RFC). Alan D. Brunelle HP OSLO S&P -- To unsubscribe from this list: send the line "unsubscribe linux-btrace" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
