On Wed, Feb 19, 2025 at 12:07:30PM -0600, Moger, Babu wrote: > Hi Dave, > > On 2/19/25 07:30, Dave Martin wrote: > > Hi, > > > > On Mon, Feb 10, 2025 at 10:10:26AM -0800, Reinette Chatre wrote: > >> Hi Babu, > >> > >> On 2/7/25 10:23 AM, Moger, Babu wrote: > >>> On 2/5/2025 5:57 PM, Reinette Chatre wrote: > >>>> On 1/22/25 12:20 PM, Babu Moger wrote: > > > > [...] > > > >>>>> MBM events of a monitoring group is tracked by hardware. Such queries > >>>>> are acceptable because of a very small number of assignable counters. > >>>> > >>>> It is not obvious what "very small number" means. Is it possible to give > >>>> a range to help reader understand the motivation? > >>> > >>> How about? > >>> > >>> MBM events of a monitoring group is tracked by hardware. Such queries > >>> are acceptable because of a very small number of assignable counters(32 to 64). > >> > >> Yes, thank you. This helps to understand the claim. > >> > >> Reinette > > > > Do these queries only happen when userspace reads an mbm_assign_control > > file? > > Yes. All these queries are initiated by userspace in the form of > individual assignments or creating a group(mkdir). > > > > > It might be worth documenting somewhere that writing and (especially) > > reading an mbm_assign_control file is not intended to be super-fast. > > > We can drop the last sentence if it is creating confusion. > > > > > It feels like userspace should not generally rely on reading > > mbm_assign_control files except for diagnostic purposes, or occasional > > read-modify-write transformations. Or do expect some other usage model > > that makes this a hotter path? > > > > Cheers > > ---Dave > > Our earlier interface was intended to query each group separately. After > the input from Peter, we changed it to batched query. One query from > userspace can list all the assignments. I am not aware of any other usage > model. Right, that's what I thought. I'll defer to Reinette on whether it's important to keep the statement about rationale -- it might indeed be easier to drop it if it just raises more questions. Cheers ---Dave
