On Thu, Apr 16, 2020 at 02:09:21PM +0800, Ming Lei wrote: > On Thu, Apr 16, 2020 at 01:47:50PM +0800, Ming Lei wrote: > > On Thu, Apr 16, 2020 at 05:25:24AM +0000, Luis Chamberlain wrote: > > > On Thu, Apr 16, 2020 at 10:10:36AM +0800, Ming Lei wrote: > > > > In theory, multiple partitions can be traced concurrently, but looks > > > > it never works, so it won't cause trouble for multiple partition trace. > > > > > > > > One userspace visible change is that blktrace debugfs dir name is switched > > > > to disk name from partition name in case of partition trace, will it > > > > break some utilities? > > > > > > How is this possible, its not clear to me, we go from: > > > > > > - q->debugfs_dir = debugfs_create_dir(kobject_name(q->kobj.parent), > > > - blk_debugfs_root); > > > > > > To this: > > > > > > + q->debugfs_dir = debugfs_create_dir(kobject_name(q->kobj.parent), > > > + blk_debugfs_root); > > > > > > > > > Maybe I am overlooking something. > > > > Your patch removes the blktrace debugfs dir: > > > > do_blk_trace_setup() > > > > - dir = debugfs_lookup(buts->name, blk_debugfs_root); > > - if (!dir) > > - bt->dir = dir = debugfs_create_dir(buts->name, blk_debugfs_root); > > - > > > > Then create blktrace attributes under the dir of q->debugfs_dir. > > > > However, buts->name could be one partition device name, but > > q->debugfs_dir has to be disk name. > > > > This change is visible to blktrace utilities. > > Just test the 1st two patches via "blktrace /dev/sda2", follows the > result, so this way can't be accepted. > > [root@ktest-01 ~]# blktrace /dev/sda2 > Thread 0 failed open /sys/kernel/debug/block/sda2/trace0: 2/No such file or directory > Thread 4 failed open /sys/kernel/debug/block/sda2/trace4: 2/No such file or directory > Thread 1 failed open /sys/kernel/debug/block/sda2/trace1: 2/No such file or directory > Thread 2 failed open /sys/kernel/debug/block/sda2/trace2: 2/No such file or directory > Thread 5 failed open /sys/kernel/debug/block/sda2/trace5: 2/No such file or directory > Thread 3 failed open /sys/kernel/debug/block/sda2/trace3: 2/No such file or directory > Thread 6 failed open /sys/kernel/debug/block/sda2/trace6: 2/No such file or directory > Thread 7 failed open /sys/kernel/debug/block/sda2/trace7: 2/No such file or directory > FAILED to start thread on CPU 0: 1/Operation not permitted > FAILED to start thread on CPU 1: 1/Operation not permitted > FAILED to start thread on CPU 2: 1/Operation not permitted > FAILED to start thread on CPU 3: 1/Operation not permitted > FAILED to start thread on CPU 4: 1/Operation not permitted > FAILED to start thread on CPU 5: 1/Operation not permitted > FAILED to start thread on CPU 6: 1/Operation not permitted > FAILED to start thread on CPU 7: 1/Operation not permitted Thanks, as I noted, I think we'd need to pre-create the directories per parition. Let me know if you think of a better alternative. Luis
