diff options
| -rw-r--r-- | include/linux/cpuset.h | 2 | ||||
| -rw-r--r-- | include/linux/mmzone.h | 85 | ||||
| -rw-r--r-- | mm/mempolicy.c | 2 | ||||
| -rw-r--r-- | mm/page_alloc.c | 188 |
4 files changed, 265 insertions, 12 deletions
diff --git a/include/linux/cpuset.h b/include/linux/cpuset.h index 4d8adf6..748d2c9 100644 --- a/include/linux/cpuset.h +++ b/include/linux/cpuset.h @@ -23,6 +23,7 @@ extern void cpuset_fork(struct task_struct *p); extern void cpuset_exit(struct task_struct *p); extern cpumask_t cpuset_cpus_allowed(struct task_struct *p); extern nodemask_t cpuset_mems_allowed(struct task_struct *p); +#define cpuset_current_mems_allowed (current->mems_allowed) void cpuset_init_current_mems_allowed(void); void cpuset_update_task_memory_state(void); #define cpuset_nodes_subset_current_mems_allowed(nodes) \ @@ -83,6 +84,7 @@ static inline nodemask_t cpuset_mems_allowed(struct task_struct *p) return node_possible_map; } +#define cpuset_current_mems_allowed (node_online_map) static inline void cpuset_init_current_mems_allowed(void) {} static inline void cpuset_update_task_memory_state(void) {} #define cpuset_nodes_subset_current_mems_allowed(nodes) (1) diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h index e06683e..09bf9d8 100644 --- a/include/linux/mmzone.h +++ b/include/linux/mmzone.h @@ -288,19 +288,94 @@ struct zone { */ #define DEF_PRIORITY 12 +/* Maximum number of zones on a zonelist */ +#define MAX_ZONES_PER_ZONELIST (MAX_NUMNODES * MAX_NR_ZONES) + +#ifdef CONFIG_NUMA +/* + * We cache key information from each zonelist for smaller cache + * footprint when scanning for free pages in get_page_from_freelist(). + * + * 1) The BITMAP fullzones tracks which zones in a zonelist have come + * up short of free memory since the last time (last_fullzone_zap) + * we zero'd fullzones. + * 2) The array z_to_n[] maps each zone in the zonelist to its node + * id, so that we can efficiently evaluate whether that node is + * set in the current tasks mems_allowed. + * + * Both fullzones and z_to_n[] are one-to-one with the zonelist, + * indexed by a zones offset in the zonelist zones[] array. + * + * The get_page_from_freelist() routine does two scans. During the + * first scan, we skip zones whose corresponding bit in 'fullzones' + * is set or whose corresponding node in current->mems_allowed (which + * comes from cpusets) is not set. During the second scan, we bypass + * this zonelist_cache, to ensure we look methodically at each zone. + * + * Once per second, we zero out (zap) fullzones, forcing us to + * reconsider nodes that might have regained more free memory. + * The field last_full_zap is the time we last zapped fullzones. + * + * This mechanism reduces the amount of time we waste repeatedly + * reexaming zones for free memory when they just came up low on + * memory momentarilly ago. + * + * The zonelist_cache struct members logically belong in struct + * zonelist. However, the mempolicy zonelists constructed for + * MPOL_BIND are intentionally variable length (and usually much + * shorter). A general purpose mechanism for handling structs with + * multiple variable length members is more mechanism than we want + * here. We resort to some special case hackery instead. + * + * The MPOL_BIND zonelists don't need this zonelist_cache (in good + * part because they are shorter), so we put the fixed length stuff + * at the front of the zonelist struct, ending in a variable length + * zones[], as is needed by MPOL_BIND. + * + * Then we put the optional zonelist cache on the end of the zonelist + * struct. This optional stuff is found by a 'zlcache_ptr' pointer in + * the fixed length portion at the front of the struct. This pointer + * both enables us to find the zonelist cache, and in the case of + * MPOL_BIND zonelists, (which will just set the zlcache_ptr to NULL) + * to know that the zonelist cache is not there. + * + * The end result is that struct zonelists come in two flavors: + * 1) The full, fixed length version, shown below, and + * 2) The custom zonelists for MPOL_BIND. + * The custom MPOL_BIND zonelists have a NULL zlcache_ptr and no zlcache. + * + * Even though there may be multiple CPU cores on a node modifying + * fullzones or last_full_zap in the same zonelist_cache at the same + * time, we don't lock it. This is just hint data - if it is wrong now + * and then, the allocator will still function, perhaps a bit slower. + */ + + +struct zonelist_cache { + DECLARE_BITMAP(fullzones, MAX_ZONES_PER_ZONELIST); /* zone full? */ + unsigned short z_to_n[MAX_ZONES_PER_ZONELIST]; /* zone->nid */ + unsigned long last_full_zap; /* when last zap'd (jiffies) */ +}; +#else +struct zonelist_cache; +#endif + /* * One allocation request operates on a zonelist. A zonelist * is a list of zones, the first one is the 'goal' of the * allocation, the other zones are fallback zones, in decreasing * priority. * - * Right now a zonelist takes up less than a cacheline. We never - * modify it apart from boot-up, and only a few indices are used, - * so despite the zonelist table being relatively big, the cache - * footprint of this construct is very small. + * If zlcache_ptr is not NULL, then it is just the address of zlcache, + * as explained above. If zlcache_ptr is NULL, there is no zlcache. */ + struct zonelist { - struct zone *zones[MAX_NUMNODES * MAX_NR_ZONES + 1]; // NULL delimited + struct zonelist_cache *zlcache_ptr; // NULL or &zlcache + struct zone *zones[MAX_ZONES_PER_ZONELIST + 1]; // NULL delimited +#ifdef CONFIG_NUMA + struct zonelist_cache zlcache; // optional ... +#endif }; #ifdef CONFIG_ARCH_POPULATES_NODE_MAP diff --git a/mm/mempolicy.c b/mm/mempolicy.c index 617fb31..fb90723 100644 --- a/mm/mempolicy.c +++ b/mm/mempolicy.c @@ -141,9 +141,11 @@ static struct zonelist *bind_zonelist(nodemask_t *nodes) enum zone_type k; max = 1 + MAX_NR_ZONES * nodes_weight(*nodes); + max++; /* space for zlcache_ptr (see mmzone.h) */ zl = kmalloc(sizeof(struct zone *) * max, GFP_KERNEL); if (!zl) return NULL; + zl->zlcache_ptr = NULL; num = 0; /* First put in the highest zones from all nodes, then all the next lower zones etc. Avoid empty zones because the memory allocator diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 23bc5bc..230771d 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -918,6 +918,126 @@ int zone_watermark_ok(struct zone *z, int order, unsigned long mark, return 1; } +#ifdef CONFIG_NUMA +/* + * zlc_setup - Setup for "zonelist cache". Uses cached zone data to + * skip over zones that are not allowed by the cpuset, or that have + * been recently (in last second) found to be nearly full. See further + * comments in mmzone.h. Reduces cache footprint of zonelist scans + * that have to skip over alot of full or unallowed zones. + * + * If the zonelist cache is present in the passed in zonelist, then + * returns a pointer to the allowed node mask (either the current + * tasks mems_allowed, or node_online_map.) + * + * If the zonelist cache is not available for this zonelist, does + * nothing and returns NULL. + * + * If the fullzones BITMAP in the zonelist cache is stale (more than + * a second since last zap'd) then we zap it out (clear its bits.) + * + * We hold off even calling zlc_setup, until after we've checked the + * first zone in the zonelist, on the theory that most allocations will + * be satisfied from that first zone, so best to examine that zone as + * quickly as we can. + */ +static nodemask_t *zlc_setup(struct zonelist *zonelist, int alloc_flags) +{ + struct zonelist_cache *zlc; /* cached zonelist speedup info */ + nodemask_t *allowednodes; /* zonelist_cache approximation */ + + zlc = zonelist->zlcache_ptr; + if (!zlc) + return NULL; + + if (jiffies - zlc->last_full_zap > 1 * HZ) { + bitmap_zero(zlc->fullzones, MAX_ZONES_PER_ZONELIST); + zlc->last_full_zap = jiffies; + } + + allowednodes = !in_interrupt() && (alloc_flags & ALLOC_CPUSET) ? + &cpuset_current_mems_allowed : + &node_online_map; + return allowednodes; +} + +/* + * Given 'z' scanning a zonelist, run a couple of quick checks to see + * if it is worth looking at further for free memory: + * 1) Check that the zone isn't thought to be full (doesn't have its + * bit set in the zonelist_cache fullzones BITMAP). + * 2) Check that the zones node (obtained from the zonelist_cache + * z_to_n[] mapping) is allowed in the passed in allowednodes mask. + * Return true (non-zero) if zone is worth looking at further, or + * else return false (zero) if it is not. + * + * This check -ignores- the distinction between various watermarks, + * such as GFP_HIGH, GFP_ATOMIC, PF_MEMALLOC, ... If a zone is + * found to be full for any variation of these watermarks, it will + * be considered full for up to one second by all requests, unless + * we are so low on memory on all allowed nodes that we are forced + * into the second scan of the zonelist. + * + * In the second scan we ignore this zonelist cache and exactly + * apply the watermarks to all zones, even it is slower to do so. + * We are low on memory in the second scan, and should leave no stone + * unturned looking for a free page. + */ +static int zlc_zone_worth_trying(struct zonelist *zonelist, struct zone **z, + nodemask_t *allowednodes) +{ + struct zonelist_cache *zlc; /* cached zonelist speedup info */ + int i; /* index of *z in zonelist zones */ + int n; /* node that zone *z is on */ + + zlc = zonelist->zlcache_ptr; + if (!zlc) + return 1; + + i = z - zonelist->zones; + n = zlc->z_to_n[i]; + + /* This zone is worth trying if it is allowed but not full */ + return node_isset(n, *allowednodes) && !test_bit(i, zlc->fullzones); +} + +/* + * Given 'z' scanning a zonelist, set the corresponding bit in + * zlc->fullzones, so that subsequent attempts to allocate a page + * from that zone don't waste time re-examining it. + */ +static void zlc_mark_zone_full(struct zonelist *zonelist, struct zone **z) +{ + struct zonelist_cache *zlc; /* cached zonelist speedup info */ + int i; /* index of *z in zonelist zones */ + + zlc = zonelist->zlcache_ptr; + if (!zlc) + return; + + i = z - zonelist->zones; + + set_bit(i, zlc->fullzones); +} + +#else /* CONFIG_NUMA */ + +static nodemask_t *zlc_setup(struct zonelist *zonelist, int alloc_flags) +{ + return NULL; +} + +static int zlc_zone_worth_trying(struct zonelist *zonelist, struct zone **z, + nodemask_t *allowednodes) +{ + return 1; +} + +static void zlc_mark_zone_full(struct zonelist *zonelist, struct zone **z) +{ +} +#endif /* CONFIG_NUMA */ + /* * get_page_from_freelist goes through the zonelist trying to allocate * a page. @@ -926,23 +1046,32 @@ static struct page * get_page_from_freelist(gfp_t gfp_mask, unsigned int order, struct zonelist *zonelist, int alloc_flags) { - struct zone **z = zonelist->zones; + struct zone **z; struct page *page = NULL; - int classzone_idx = zone_idx(*z); + int classzone_idx = zone_idx(zonelist->zones[0]); struct zone *zone; + nodemask_t *allowednodes = NULL;/* zonelist_cache approximation */ + int zlc_active = 0; /* set if using zonelist_cache */ + int did_zlc_setup = 0; /* just call zlc_setup() one time */ +zonelist_scan: /* - * Go through the zonelist once, looking for a zone with enough free. + * Scan zonelist, looking for a zone with enough free. * See also cpuset_zone_allowed() comment in kernel/cpuset.c. */ + z = zonelist->zones; + do { + if (NUMA_BUILD && zlc_active && + !zlc_zone_worth_trying(zonelist, z, allowednodes)) + continue; zone = *z; if (unlikely(NUMA_BUILD && (gfp_mask & __GFP_THISNODE) && zone->zone_pgdat != zonelist->zones[0]->zone_pgdat)) break; if ((alloc_flags & ALLOC_CPUSET) && !cpuset_zone_allowed(zone, gfp_mask)) - continue; + goto try_next_zone; if (!(alloc_flags & ALLOC_NO_WATERMARKS)) { unsigned long mark; @@ -956,15 +1085,30 @@ get_page_from_freelist(gfp_t gfp_mask, unsigned int order, classzone_idx, alloc_flags)) { if (!zone_reclaim_mode || !zone_reclaim(zone, gfp_mask, order)) - continue; + goto this_zone_full; } } page = buffered_rmqueue(zonelist, zone, order, gfp_mask); if (page) break; - +this_zone_full: + if (NUMA_BUILD) + zlc_mark_zone_full(zonelist, z); +try_next_zone: + if (NUMA_BUILD && !did_zlc_setup) { + /* we do zlc_setup after the first zone is tried */ + allowednodes = zlc_setup(zonelist, alloc_flags); + zlc_active = 1; + did_zlc_setup = 1; + } } while (*(++z) != NULL); + + if (unlikely(NUMA_BUILD && page == NULL && zlc_active)) { + /* Disable zlc cache for second zonelist scan */ + zlc_active = 0; + goto zonelist_scan; + } return page; } @@ -1535,6 +1679,24 @@ static void __meminit build_zonelists(pg_data_t *pgdat) } } +/* Construct the zonelist performance cache - see further mmzone.h */ +static void __meminit build_zonelist_cache(pg_data_t *pgdat) +{ + int i; + + for (i = 0; i < MAX_NR_ZONES; i++) { + struct zonelist *zonelist; + struct zonelist_cache *zlc; + struct zone **z; + + zonelist = pgdat->node_zonelists + i; + zonelist->zlcache_ptr = zlc = &zonelist->zlcache; + bitmap_zero(zlc->fullzones, MAX_ZONES_PER_ZONELIST); + for (z = zonelist->zones; *z; z++) + zlc->z_to_n[z - zonelist->zones] = zone_to_nid(*z); + } +} + #else /* CONFIG_NUMA */ static void __meminit build_zonelists(pg_data_t *pgdat) @@ -1572,14 +1734,26 @@ static void __meminit build_zonelists(pg_data_t *pgdat) } } +/* non-NUMA variant of zonelist performance cache - just NULL zlcache_ptr */ +static void __meminit build_zonelist_cache(pg_data_t *pgdat) +{ + int i; + + for (i = 0; i < MAX_NR_ZONES; i++) + pgdat->node_zonelists[i].zlcache_ptr = NULL; +} + #endif /* CONFIG_NUMA */ /* return values int ....just for stop_machine_run() */ static int __meminit __build_all_zonelists(void *dummy) { int nid; - for_each_online_node(nid) + + for_each_online_node(nid) { build_zonelists(NODE_DATA(nid)); + build_zonelist_cache(NODE_DATA(nid)); + } return 0; } |