Messages in this thread | | | Date | Tue, 14 Apr 2009 11:13:23 +0800 | From | Li Zefan <> | Subject | Re: [PATCH] blktrace: move trace/ dir to /sys/block/sda/ |
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Jens Axboe wrote: > On Mon, Apr 13 2009, Li Zefan wrote: >> Impact: allow ftrace-plugin blktrace to trace device-mapper devices >> >> blktrace can't trace a single partition, so it makes no sense to >> have one trace/ dir in each /sys/block/sda/sdaX. Move it to >> /sys/block/sda/. >> >> Thus we fix an issue reported by Ted, that ftrace-plugin blktrace >> can't be used to trace device-mapper devices. > > Perhaps I never committed that patch, but it would be trivial to do > partition based blktrace tracing. It's also quite useful. So please > don't go changing things to make that harder to support, it would be > nicer to just add the (small) bits to support per-partition tracing. > It's basically just a start/stop sector range, while some events are > per-device and should just be included always. >
Ok, I found that patch in btrace mailing list. I'll rebase it and send it out.
How about just add trace/ to /sys/block/sda? Then if we want to trace the whole sda, we can: # echo 1 > /sys/block/sda/enable If we want to trace a single partition: # echo 1 > /sys/block/sda/sda1/enable
Like "btrace /dev/sda" and "btrace /dev/sda1" when using userspace blktrace.
And when this is done, tracing device-mapper is supported, and I think current md devices can't be traced by ftrace-plugin blktrace too.
-- Zefan
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