Ingo Molnar wrote: > * 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. > No, both userspace blktrace and ftrace-plugin trace can trace more than one device at a time. # btrace /dev/sda /dev/dm-0 or # echo 1 > /sys/block/sda/trace/enable # echo 1 > /sys/block/dm-0/trace/enable > 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. > Actually action mask can be specified by 'blktrace -a/-A mask/mask_name' But yes the pid filter is not exposed in user-space blktrace. > 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
