On Thu, May 02, 2024 at 10:52:15AM -0700, Reinette Chatre wrote: > Hi Dave, > > On 5/2/2024 9:21 AM, Dave Martin wrote: > > On Thu, Mar 28, 2024 at 08:06:50PM -0500, Babu Moger wrote: > >> diff --git a/Documentation/arch/x86/resctrl.rst b/Documentation/arch/x86/resctrl.rst > >> index 2d96565501ab..64ec70637c66 100644 > >> --- a/Documentation/arch/x86/resctrl.rst > >> +++ b/Documentation/arch/x86/resctrl.rst > >> @@ -328,6 +328,77 @@ with the following files: > >> None of events are assigned on this mon group. This is a child > >> monitor group of the non default control mon group. > >> > >> + Assignment state can be updated by writing to this interface. > >> + > >> + NOTE: Assignment on one domain applied on all the domains. User can > >> + pass one valid domain and assignment will be updated on all the > >> + available domains. > >> + > >> + Format is similar to the list format with addition of op-code for the > >> + assignment operation. > >> + > >> + * Default CTRL_MON group: > >> + "//<domain_id><op-code><assignment_flags>" > >> + > >> + * Non-default CTRL_MON group: > >> + "<CTRL_MON group>//<domain_id><op-code><assignment_flags>" > >> + > >> + * Child MON group of default CTRL_MON group: > >> + "/<MON group>/<domain_id><op-code><assignment_flags>" > >> + > >> + * Child MON group of non-default CTRL_MON group: > >> + "<CTRL_MON group>/<MON group>/<domain_id><op-code><assignment_flags>" > > > > The final bullet seems to cover everything, if we allow <CTRL_MON group> > > and <MON group> to be independently empty strings to indicate the > > default control and/or monitoring group respectively. > > > > Would that be simpler than treating this as four separate cases? > > > > Also, will this go wrong if someone creates a resctrl group with '\n' > > (i.e., a newline character) in the name? > > There is a check for this in rdtgroup_mkdir(). Ah, right. Found it. I guess that works. On a (sort of) related point, are there any concerns about namespace clashes in resctrlfs? This looks like a potential issue for the resctrl top-level directory at least. It's not clear to me how userspace can pick a name for a resctrl group that is guaranteed not to clash with the name of one of resctrl's own files in a future kernel. (Note, this is nothing to do with series; I haven't been sure where to fit this into the dicsussion...) > > > > >> + > >> + Op-code can be one of the following: > >> + :: > >> + > >> + = Update the assignment to match the flags > >> + + Assign a new state > >> + - Unassign a new state > >> + _ Unassign all the states > > > > I can't remember whether I already asked this, but is "_" really > > needed here? > > Asked twice: > https://lore.kernel.org/lkml/ZiaRXrmDDjc194JI@xxxxxxxxxxxxxxx/ > https://lore.kernel.org/lkml/ZiervIprcwoApAqw@xxxxxxxxxxxxxxx/ > > Answered: > https://lore.kernel.org/lkml/4cd220cc-2e8e-4193-b01a-d3cd798c7118@xxxxxxx/ > > You seemed ok with answer then: > https://lore.kernel.org/lkml/ZiffF93HM8bE3qo7@xxxxxxxxxxxxxxx/ There, I was asking about "_" meaning "no flags" in "=_". > > > > > Wouldn't it be the case that > > > > //*_ > > > > would mean just the same thing as > > > > //*=_ > > > > ...? (assuming the "*" = "all domains" convention already discussed) > > > > Maybe I'm missing something here. > > I believe have an explicit operator ("+", "=", or "-") simplifies > parsing while providing an interface consistent with what users are already > used to. > > Reinette That was the point I was trying to make here, apologies if I wasn't clear. Cheers ---Dave
