On Thu, Apr 12, 2018 at 5:11 PM, Dave Anderson <anderson@xxxxxxxxxx> wrote: > > ----- Original Message ----- >> On Thu, Apr 12, 2018 at 3:57 PM, Dave Anderson <anderson@xxxxxxxxxx> wrote: >> > >> > Daniel, >> > >> > Hmmm, when looking at your example, I just noticed it didn't use the -t >> > argument, >> > but then looking at the code realized that the command defaults to rbtrees. >> > I >> > actually don't think that was the original intent, but maybe that fact >> > should >> > should be indicated in the help page? Although I can't come up with a >> > compelling >> > argument why one should be the default. Either that, or -t should be >> > enforced. >> >> Wow. I didn't know this was not intended. I thought that red-black is >> default as radix trees are only used in address_space of mapped files >> (page cache), AFAIK. I usually do not need to specify the type as all >> the major trees are red-black - being it cgroups, scheduler entities, >> memory mappings, inodes, you name it. >> >> Again, I didn't change anything with regards to this behavior. > > OK, that's a good point. So let's declare the default at top of the help > page "-t type" segment. > >> >> > Anyway, you probably didn't notice that all help page output is constrained >> > to 80 columns. Your example command alone is 162 bytes long, making it way >> > too confusing to figure out what the command is doing. Can you just show >> > the command output without piping it to an external command, or make a much >> > simpler example? And also keep it to 80 columns or less, >> >> I was thinking about wrapping the command to a second line but that's >> what terminal will do anyways if narrower so I left it that way. The >> rest of the pipe is just formatting/pretty printing the table. >> Otherwise the output would be waaaay toooo loooong and not really >> human readable. I do not think it can get any simpler than that. I can >> get rid of one of the columns though, it does not need to contain both >> the start and the end of the VMA range. >> >> As an added value it also teaches eventual readers some advanced usage >> techniques in general so I believe it can be useful. There is enough >> simple examples already. Would you rather prefer something like this? >> >> crash> task -R mm >> PID: 28682 TASK: ffff880036d4af10 CPU: 0 COMMAND: "crash" >> mm = 0xffff880074b5be80, >> >> crash> tree -lp -o vm_area_struct.vm_rb -r mm_struct.mm_rb 0xffff880074b5be80 >> ffff88001f2c50e0 >> position: root/l/l/l/l/l >> ffff88001f2c5290 >> position: root/l/l/l/l >> ffff880074bfc6c0 >> position: root/l/l/l/l/r >> ffff88001f2c4bd0 >> position: root/l/l/l >> ffff880074bfc948 >> position: root/l/l/l/r/l/l >> ffff880036e54510 >> position: root/l/l/l/r/l/l/r >> ffff88001f2c5bd8 >> position: root/l/l/l/r/l >> ffff880036e54af8 >> position: root/l/l/l/r/l/r/l >> ffff880036e54f30 >> position: root/l/l/l/r/l/r >> ffff88000e06aa20 >> position: root/l/l/l/r/l/r/r >> ffff88000e06b368 >> position: root/l/l/l/r >> ffff88000e06ba28 >> position: root/l/l/l/r/r/l >> ffff88000e06ae58 >> position: root/l/l/l/r/r >> ffff88000e06a6c0 >> position: root/l/l/l/r/r/r >> ... >> ffff88001f2c51b8 >> position: root/l/r/r/r/l >> ffff88001f2c4d80 >> position: root/l/r/r/r >> ffff880074bfd878 >> position: root/l/r/r/r/r >> ffff88001f2c5a28 >> position: root >> ffff88001f2c4a20 >> position: root/r/l/l/l >> ffff88001f2c4360 >> position: root/r/l/l >> ffff880074bfcaf8 >> position: root/r/l/l/r >> ... >> ffff88001f2c5e60 >> position: root/r/r/l/l/l >> ffff88001f2c4ca8 >> position: root/r/r/l/l >> ffff88001f2c5008 >> position: root/r/r/l >> ffff88001f2c5d88 >> position: root/r/r/l/r >> ffff880074bfd6c8 >> position: root/r/r/l/r/r >> ffff88001f2c4288 >> position: root/r/r >> ffff88001f2c4510 >> position: root/r/r/r >> ffff88001f2c5b00 >> position: root/r/r/r/r >> >> This is not as readable in my opinion. And also it does not show why >> would one care about the order in the first place. See? > > Yes, that's what I'm looking for. You can also remove the "task" command, > and just say something in the leading description like, "Given an mm_struct > address of 0xffff880074b5be80, ..." > As far as caring about the order, you could add the "-s vm_area_struct.vm_start" > option, and indicate that the -l option would display the vm_start addresses > in an ascending value. That would obviously overflow the command line, but you > could use a numeric argument for the -o argument as is done in a few other > examples above that. > >> I do not believe a hard limit of 80 columns is useful for any serious >> kernel debugging. For developing and maintaining a source code, yes. >> For dumping a lot of debugging data in a human readable form, no. > > I don't care about the length of any command output, I'm just talking about > the output examples in the help page data. I see. I'm gonna use the example from my last email. That's simple enough and clean. Will send v2 tomorrow. --nX > > Thanks, > Dave > > -- Crash-utility mailing list Crash-utility@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/crash-utility
