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? Jan
