On 21.03.2024 18:22, Carlo Nonato wrote: > Hi Jan, > > On Thu, Mar 21, 2024 at 4:53 PM Jan Beulich <jbeul...@suse.com> wrote: >> >> On 21.03.2024 16:03, Carlo Nonato wrote: >>> On Tue, Mar 19, 2024 at 3:58 PM Jan Beulich <jbeul...@suse.com> wrote: >>>> On 15.03.2024 11:58, Carlo Nonato wrote: >>>>> --- a/docs/misc/xen-command-line.pandoc >>>>> +++ b/docs/misc/xen-command-line.pandoc >>>>> @@ -1706,6 +1706,43 @@ This option is intended for debugging purposes >>>>> only. Enable MSR_DEBUGCTL.LBR >>>>> in hypervisor context to be able to dump the Last Interrupt/Exception >>>>> To/From >>>>> record with other registers. >>>>> >>>>> +### llc-coloring >>>>> +> `= <boolean>` >>>>> + >>>>> +> Default: `false` >>>>> + >>>>> +Flag to enable or disable LLC coloring support at runtime. This option is >>>>> +available only when `CONFIG_LLC_COLORING` is enabled. See the general >>>>> +cache coloring documentation for more info. >>>>> + >>>>> +### llc-nr-ways >>>>> +> `= <integer>` >>>>> + >>>>> +> Default: `Obtained from hardware` >>>>> + >>>>> +Specify the number of ways of the Last Level Cache. This option is >>>>> available >>>>> +only when `CONFIG_LLC_COLORING` is enabled. LLC size and number of ways >>>>> are used >>>>> +to find the number of supported cache colors. By default the value is >>>>> +automatically computed by probing the hardware, but in case of specific >>>>> needs, >>>>> +it can be manually set. Those include failing probing and >>>>> debugging/testing >>>>> +purposes so that it's possibile to emulate platforms with different >>>>> number of >>>>> +supported colors. If set, also "llc-size" must be set, otherwise the >>>>> default >>>>> +will be used. >>>>> + >>>>> +### llc-size >>>>> +> `= <size>` >>>>> + >>>>> +> Default: `Obtained from hardware` >>>>> + >>>>> +Specify the size of the Last Level Cache. This option is available only >>>>> when >>>>> +`CONFIG_LLC_COLORING` is enabled. LLC size and number of ways are used >>>>> to find >>>>> +the number of supported cache colors. By default the value is >>>>> automatically >>>>> +computed by probing the hardware, but in case of specific needs, it can >>>>> be >>>>> +manually set. Those include failing probing and debugging/testing >>>>> purposes so >>>>> +that it's possibile to emulate platforms with different number of >>>>> supported >>>>> +colors. If set, also "llc-nr-ways" must be set, otherwise the default >>>>> will be >>>>> +used. >>>> >>>> Wouldn't it make sense to infer "llc-coloring" when both of the latter >>>> options >>>> were supplied? >>> >>> To me it looks a bit strange that specifying some attributes of the cache >>> automatically enables cache coloring. Also it would require some changes in >>> how to express the auto-probing for such attributes. >> >> Whereas to me it looks strange that, when having llc-size and llc-nr-ways >> provided, I'd need to add a 3rd option. What purpose other than enabling >> coloring could there be when specifying those parameters? > > Ok, I probably misunderstood you. You mean just to assume llc-coloring=on > when both llc-size and llc-nr-ways are present and not to remove > llc-coloring completely, right?
Yes. The common thing, after all, will be to just have llc-coloring on the command line. Jan
