From 529a340402e419f935d411ce0a085e96fcaf3872 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Sat, 5 Nov 2005 17:25:54 +0100 Subject: [PATCH] [PATCH] x86_64: Optimize NUMA node hash function Compute the highest possible value for memnode_shift, in order to reduce footprint of memnodemap[] to the minimum, thus making all users (phys_to_nid(), kfree()), more cache friendly. Before the patch : Node 0 MemBase 0000000000000000 Limit 00000001ffffffff Node 1 MemBase 0000000200000000 Limit 00000003ffffffff Using 23 for the hash shift. Max adder is 3ffffffff After the patch : Node 0 MemBase 0000000000000000 Limit 00000001ffffffff Node 1 MemBase 0000000200000000 Limit 00000003ffffffff Using 33 for the hash shift. In this case, only 2 bytes of memnodemap[] are used, instead of 2048 Signed-off-by: Eric Dumazet Signed-off-by: Andi Kleen Signed-off-by: Linus Torvalds --- arch/x86_64/mm/numa.c | 67 +++++++++++++++++++++++++++---------------- 1 file changed, 43 insertions(+), 24 deletions(-) diff --git a/arch/x86_64/mm/numa.c b/arch/x86_64/mm/numa.c index 4bf64583ba..edd5559380 100644 --- a/arch/x86_64/mm/numa.c +++ b/arch/x86_64/mm/numa.c @@ -38,38 +38,57 @@ cpumask_t node_to_cpumask[MAX_NUMNODES] __read_mostly; int numa_off __initdata; -int __init compute_hash_shift(struct node *nodes, int numnodes) + +/* + * Given a shift value, try to populate memnodemap[] + * Returns : + * 1 if OK + * 0 if memnodmap[] too small (of shift too small) + * -1 if node overlap or lost ram (shift too big) + */ +static int __init populate_memnodemap( + const struct node *nodes, int numnodes, int shift) { int i; - int shift = 20; - unsigned long addr,maxend=0; - - for (i = 0; i < numnodes; i++) - if ((nodes[i].start != nodes[i].end) && (nodes[i].end > maxend)) - maxend = nodes[i].end; + int res = -1; + unsigned long addr, end; - while ((1UL << shift) < (maxend / NODEMAPSIZE)) - shift++; - - printk (KERN_DEBUG"Using %d for the hash shift. Max adder is %lx \n", - shift,maxend); - memset(memnodemap,0xff,sizeof(*memnodemap) * NODEMAPSIZE); + memset(memnodemap, 0xff, sizeof(memnodemap)); for (i = 0; i < numnodes; i++) { - if (nodes[i].start == nodes[i].end) + addr = nodes[i].start; + end = nodes[i].end; + if (addr >= end) continue; - for (addr = nodes[i].start; - addr < nodes[i].end; - addr += (1UL << shift)) { - if (memnodemap[addr >> shift] != 0xff) { - printk(KERN_INFO - "Your memory is not aligned you need to rebuild your kernel " - "with a bigger NODEMAPSIZE shift=%d adder=%lu\n", - shift,addr); + if ((end >> shift) >= NODEMAPSIZE) + return 0; + do { + if (memnodemap[addr >> shift] != 0xff) return -1; - } memnodemap[addr >> shift] = i; - } + addr += (1 << shift); + } while (addr < end); + res = 1; } + return res; +} + +int __init compute_hash_shift(struct node *nodes, int numnodes) +{ + int shift = 20; + + while (populate_memnodemap(nodes, numnodes, shift + 1) >= 0) + shift++; + + printk(KERN_DEBUG "Using %d for the hash shift.\n", + shift); + + if (populate_memnodemap(nodes, numnodes, shift) != 1) { + printk(KERN_INFO + "Your memory is not aligned you need to rebuild your kernel " + "with a bigger NODEMAPSIZE shift=%d\n", + shift); + return -1; + } return shift; } -- 2.39.5