Hi Maciej, On 3/20/2024 8:21 AM, Maciej Wieczor-Retman wrote: > Hi Reinette, > > On 2024-03-19 at 10:51:14 -0700, Reinette Chatre wrote: >> What remains is the user interface that continues to gather opinions [3]. These new >> discussions were prompted by user space needing a way to determine if resctrl supports >> SNC. This started by using the "size" file but thinking about it more user space could >> also look at whether the number of L3 control domains are different from the number >> of L3 monitoring domains? I am adding Maciej for his opinion (please also include him >> in future versions of this series). > > By this do you mean comparing the contents of main "schemata" file with the > number of mon_L3_* files? (assuming you mean mon_L3_* directories) Yes, the "schemata" file can be used. There is also the "bit_usage" file in the info directory that indicates how many control domains there are. Do you think doing so also falls into the "not obvious text parsing and size comparison" category? > >> Apart from the user space requirement to know if SNC is supported by resctrl there >> is also the interface with which user space obtains the monitoring data. >> James highlighted [1] that the interface used in this series uses existing files to >> represent different content, and can thus be considered as "broken". It is not obvious >> to me how to "fix" this. Should we continue to explore interfaces like [2] that >> attempts to add SNC support into resctrl or should the message continue to be >> that SNC "plays havoc with the RDT monitoring features" and users wanting to use >> SNC and RDT at the same time are expected to adapt to the peculiar interface ... >> or is the preference that after this series "SNC and RDT are compatible" and >> thus presented with an intuitive interface? > > I kind of liked this idea [1]. Hiding SNC related information behind some not > obvious text parsing and size comparisons might eliminate any ease of use for > userspace applications. But I agree with you [2] that it's hard to predict the > future for this interface and any potential problems with setting up this > file structure. Thanks to you for trying this out from user space side and highlighting the difficulty trying to do so. Reinette > > [1] https://lore.kernel.org/all/SJ1PR11MB608309F47C00F964E16205D6FC2D2@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx/ > [2] https://lore.kernel.org/all/7f15a700-f23a-48f9-b335-13ea1735ad84@xxxxxxxxx/ >
