On 26.02.2026 15:29, Bernhard Kaindl wrote: > From: Alejandro Vallejo <[email protected]> > > Add per-node free page counters (node_avail_pages[]), protected by > heap_lock, updated in real-time in lockstep with total_avail_pages > as pages are allocated and freed. > > This replaces the avail_heap_pages() loop over all online nodes and > zones in avail_node_heap_pages() with a direct O(1) array lookup, > making it efficient to get the total free pages for a given NUMA node. > > The per-node counts are currently provided using sysctl for NUMA > placement decisions of domain builders and monitoring, and for > debugging with the debug-key 'u' to print NUMA info to the printk buffer. > > They will also be used for checking if a NUMA node may be able to > satisfy a NUMA-node-specific allocation by comparing node availability > against node-specific claims before looking for pages in the zones > of the node. > > Also change total_avail_pages and outstanding_claims to unsigned long: > > Those never become negative (we protect that with ASSERT/BUG_ON already), > and converting them to unsigned long makes that explicit, and also > fixes signed/unsigned comparison warnings.
This wants to be a separate commit. It hasn't got anything to do in here. > This only needs moving the ASSERT to before the subtraction. > See the previous commit moving the BUG_ON for outstanding_claims. Please can you avoid such statements? You won't know in which order the patches are committed: Patch 01 may go in weeks or months before patch 02. > --- a/xen/common/page_alloc.c > +++ b/xen/common/page_alloc.c > @@ -483,11 +483,32 @@ static heap_by_zone_and_order_t *_heap[MAX_NUMNODES]; > > static unsigned long node_need_scrub[MAX_NUMNODES]; > > +/* avail[node][zone] is the number of free pages on that node and zone. */ > static unsigned long *avail[MAX_NUMNODES]; > -static long total_avail_pages; > +/* Global available pages, updated in real-time, protected by heap_lock */ > +static unsigned long total_avail_pages; > > +/* The global heap lock, protecting access to the heap and related > structures */ > static DEFINE_SPINLOCK(heap_lock); > -static long outstanding_claims; /* total outstanding claims by all domains */ > + > +/* > + * Per-node count of available pages, protected by heap_lock, updated in > + * lockstep with total_avail_pages as pages are allocated and freed. > + * > + * Each entry holds the sum of avail[node][zone] across all zones, used for > + * efficiently checking node-local availability for allocation requests. > + * Also provided via sysctl for NUMA placement decisions of domain builders > + * and monitoring, and logged with debug-key 'u' for NUMA debugging. > + * > + * Maintaining this under heap_lock does not reduce scalability, as the > + * allocator is already serialized on it. The accessor macro abstracts the > + * storage to ease future changes (e.g. moving to per-node lock granularity). > + */ > +#define node_avail_pages(node) (node_avail_pages[node]) This isn't really needed when ... > +static unsigned long node_avail_pages[MAX_NUMNODES]; ... it's a static array anyway. Plus you may want to talk to Andrew regarding the use of such a macro as an lvalue. > +/* total outstanding claims by all domains */ > +static unsigned long outstanding_claims; As you touch it, comment style wants correcting. Jan
