Yu Zhao <[email protected]> writes: > On Mon, Mar 14, 2022 at 2:09 AM Huang, Ying <[email protected]> wrote: >> >> Hi, Yu, >> >> Yu Zhao <[email protected]> writes: >> > diff --git a/mm/Kconfig b/mm/Kconfig >> > index 3326ee3903f3..747ab1690bcf 100644 >> > --- a/mm/Kconfig >> > +++ b/mm/Kconfig >> > @@ -892,6 +892,16 @@ config ANON_VMA_NAME >> > area from being merged with adjacent virtual memory areas due to >> > the >> > difference in their name. >> > >> > +# the multi-gen LRU { >> > +config LRU_GEN >> > + bool "Multi-Gen LRU" >> > + depends on MMU >> > + # the following options can use up the spare bits in page flags >> > + depends on !MAXSMP && (64BIT || !SPARSEMEM || SPARSEMEM_VMEMMAP) >> >> LRU_GEN depends on !MAXSMP. So, What is the maximum NR_CPUS supported >> by LRU_GEN? > > LRU_GEN doesn't really care about NR_CPUS. IOW, it doesn't impose a > max number. The dependency is with NODES_SHIFT selected by MAXSMP: > default "10" if MAXSMP > This combined with LAST_CPUPID_SHIFT can exhaust the spare bits in page flags.
From the following code snippets from page-flags-layout.h, LAST_CPUPID_SHIFT is related to NR_CPUS instead of NODES_SHIFT. #define LAST__PID_SHIFT 8 #define LAST__PID_MASK ((1 << LAST__PID_SHIFT)-1) #define LAST__CPU_SHIFT NR_CPUS_BITS #define LAST__CPU_MASK ((1 << LAST__CPU_SHIFT)-1) #define LAST_CPUPID_SHIFT (LAST__PID_SHIFT+LAST__CPU_SHIFT) Best Regards, Huang, Ying [snip] _______________________________________________ kernel mailing list -- [email protected] To unsubscribe send an email to [email protected] Fedora Code of Conduct: https://docs.fedoraproject.org/en-US/project/code-of-conduct/ List Guidelines: https://fedoraproject.org/wiki/Mailing_list_guidelines List Archives: https://lists.fedoraproject.org/archives/list/[email protected] Do not reply to spam on the list, report it: https://pagure.io/fedora-infrastructure
