On Tue, Jun 16, 2015 at 03:27:48PM -0400, Mikulas Patocka wrote: > > > On Tue, 16 Jun 2015, Vivek Goyal wrote: > > > On Tue, Jun 09, 2015 at 05:21:39PM -0400, Mikulas Patocka wrote: > > > > [..] > > > Messages > > > ======== > > > > > > - @stats_create <range> <step> [<program_id> [<aux_data>]] > > > + @stats_create <range> <step> > > > + [<number_of_optional_arguments> <optional_arguments>...] > > > + [<program_id> [<aux_data>]] > > > > > > Create a new region and return the region_id. > > > > > > @@ -48,6 +54,17 @@ Messages > > > "/<number_of_areas>" - the range is subdivided into the specified > > > number of areas. > > > > > > + <number_of_optional_arguments> > > > + The number of optional arguments > > > + > > > + <optional_arguments> > > > + The following optional arguments are supported > > > + precise_timestamps - use precise timer with nanosecond resolution > > > + instead of the "jiffies" variable. When this argument is > > > + used, the resulting times are in nanoseconds instead of > > > + milliseconds. Precise timestamps are a little bit slower > > > + to obtain than jiffies-based timestamps. > > > + > > > > Instead of "precise_timestams" will it make sense to call it > > "nanosecond_timestamps" or "ns_timestamps". > > > > > > > <program_id> > > > An optional parameter. A name that uniquely identifies > > > the userspace owner of the range. This groups ranges together > > > > We are adding these new parameters/arguments in between existing parameters. > > Will it break any of the existing scritps. Will it make sense to add these > > new parameters at the end. It is more intuitive. > > It could break someone who uses number as program_id - but there is no > program on Linux with name that is a pure number. > There does not seem to be any restriction that program_id has to be a valid program name. It could be any string. I used a program id of 25 and it works. [root@tiger ~]# dmsetup message docker-docker--pool 0 @stats_create - /1 25 0 [root@tiger ~]# dmsetup message docker-docker--pool 0 @stats_create - /2 30 1 [root@tiger ~]# dmsetup message docker-docker--pool 0 @stats_list 25 0: 0+585465856 585465856 25 - [root@tiger ~]# dmsetup message docker-docker--pool 0 @stats_list 0: 0+585465856 585465856 25 - 1: 0+585465856 292732928 30 - May be we can introduce a new message to handle this new number of arguments syntax. Say "stats_create_v2". That way existing programs will not be broken, if any. > We can't add it at the end because program_id and aux_data are already > optional arguments. > > > Also, I was wondering that why do we need to introduce this notion of > > number of optional arguments. Can't we just introduce another optional > > parameter [ns_timestamps]. That feels little simpler. > > Then, it will clash with program_id "ns_timestamps". Device mapper uses > this "number of optional arguments" notation at other places, so I used it > too, BTW, I have a very stupid question. This probably stems from the fact that I don't know enough about dm argument parsing. Why can't I pass the argument in same format as command line. So how about. @stats_create [program_id=<program_id>] [aux_data=<aux_data>] That way we know what arguments are coming. There is no guessing and handling optional parameters is easy too. Thanks Vivek -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
