* Li Zefan <lizf@xxxxxxxxxxxxxx> wrote: > From: Shawn Du <duyuyang@xxxxxxxxx> > > Though one can specify '-d /dev/sda1' when using blktrace, it > still traces the whole sda. > > To support per-partition tracing, when we start tracing, we > initialize bt->start_lba and bt->end_lba to the start and end > sector of that partition. > > Note some actions are per device, thus we don't filter 0-sector > events. > > The original patch and discussion can be found here: > http://marc.info/?l=linux-btrace&m=122949374214540&w=2 > > Signed-off-by: Shawn Du <duyuyang@xxxxxxxxx> > Signed-off-by: Li Zefan <lizf@xxxxxxxxxxxxxx> Thanks - beyond the small detail i mailed about a few minutes ago the series looks good: i'll queue this up in tracing/blktrace unless Jens has second thoughts. Lets note that this approach still has the (long existing) limitation that only one device can be block-traced at a time. Furthermore, various other aspects of act_log_check() itself could be expressed in terms of per tracepoint filters as well: the PID filter field for example - which is supported in the ioctl ABI but currently not exposed in the user-space blktrace utility. Same goes for the action mask which is frequently used. But before we can lift all these limitations and can have equivalent functionality in the generic event tracer we still need more filter engine infrastructure work (range operators and dev_t field support). Plus TRACE_EVENT() based blk tracepoints. Once we have that, the conversion will be straightforward: all existing filter functionality of blktrace is static, so it will map directly to new-style filter expressions. That will give us block tracing for an arbitrary number of block devices (including the basic mode of 'trace all block IO in the system') and a much wider range of filtering capabilities. Thanks, Ingo -- 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
