I didn't expect node with so smcall hunk, as explained in the comments to 20599.
But for this specific SRAT, seems we can also improve constructing of
node_memblk_range[], so that we can merge 0~a0000 with 100000-80000000, and
80000000-d0000000 with 100000000-130000000. Depends on whether we need keep
BIOS's memory affinity information, we can either create a new structure to
hold the result, or we can simply compact node_memblk_range[]. The benefit is,
we can reduce the sizeof memnodemap, but I'm not sure if it is needed still
after this patch.
Thanks
--jyh
>-----Original Message-----
>From: Jan Beulich [mailto:JBeulich@xxxxxxxxxx]
>Sent: Wednesday, January 06, 2010 11:36 PM
>To: xen-devel@xxxxxxxxxxxxxxxxxxx
>Cc: Jiang, Yunhong
>Subject: [PATCH] x86: fix NUMA handling (c/s 20599)
>
>c/s 20599 caused the hash shift to become significantly smaller on
>systems with an SRAT like this
>
>(XEN) SRAT: Node 0 PXM 0 0-a0000
>(XEN) SRAT: Node 0 PXM 0 100000-80000000
>(XEN) SRAT: Node 1 PXM 1 80000000-d0000000
>(XEN) SRAT: Node 1 PXM 1 100000000-130000000
>
>Comined with the static size of the memnodemap[] array, NUMA got
>therefore disabled on such systems. The backport from Linux was really
>incomplete, as Linux much earlier had already introduced a dynamcially
>allocated memnodemap[].
>
>Further, doing to/from pdx translations on addresses just past a valid
>range is not correct, as it may strip/fail to insert non-zero bits in
>this case.
>
>Finally, using 63 as the cover-it-all shift value is invalid on 32bit,
>since pdx values are unsigned long.
>
>Signed-off-by: Jan Beulich <jbeulich@xxxxxxxxxx>
>
>--- 2010-01-06.orig/xen/arch/x86/numa.c 2010-01-06 15:16:18.000000000
>+0100
>+++ 2010-01-06/xen/arch/x86/numa.c 2010-01-06 16:10:59.000000000 +0100
>@@ -30,7 +30,9 @@ struct node_data node_data[MAX_NUMNODES]
>
> /* Mapping from pdx to node id */
> int memnode_shift;
>-u8 memnodemap[NODEMAPSIZE];
>+static typeof(*memnodemap) _memnodemap[2];
>+unsigned long memnodemapsize;
>+u8 *memnodemap;
>
> unsigned char cpu_to_node[NR_CPUS] __read_mostly = {
> [0 ... NR_CPUS-1] = NUMA_NO_NODE
>@@ -62,13 +64,13 @@ static int __init populate_memnodemap(co
> unsigned long spdx, epdx;
> int i, res = -1;
>
>- memset(memnodemap, NUMA_NO_NODE, sizeof(memnodemap));
>+ memset(memnodemap, NUMA_NO_NODE, memnodemapsize *
>sizeof(*memnodemap));
> for (i = 0; i < numnodes; i++) {
> spdx = paddr_to_pdx(nodes[i].start);
>- epdx = paddr_to_pdx(nodes[i].end);
>+ epdx = paddr_to_pdx(nodes[i].end - 1) + 1;
> if (spdx >= epdx)
> continue;
>- if ((epdx >> shift) >= NODEMAPSIZE)
>+ if ((epdx >> shift) >= memnodemapsize)
> return 0;
> do {
> if (memnodemap[spdx >> shift] != NUMA_NO_NODE)
>@@ -86,6 +88,28 @@ static int __init populate_memnodemap(co
> return res;
> }
>
>+static int __init allocate_cachealigned_memnodemap(void)
>+{
>+ unsigned long size = PFN_UP(memnodemapsize * sizeof(*memnodemap));
>+ unsigned long mfn = alloc_boot_pages(size, 1);
>+
>+ if (!mfn) {
>+ printk(KERN_ERR
>+ "NUMA: Unable to allocate Memory to Node hash map\n");
>+ memnodemapsize = 0;
>+ return -1;
>+ }
>+
>+ memnodemap = mfn_to_virt(mfn);
>+ mfn <<= PAGE_SHIFT;
>+ size <<= PAGE_SHIFT;
>+ printk(KERN_DEBUG "NUMA: Allocated memnodemap from %lx - %lx\n",
>+ mfn, mfn + size);
>+ memnodemapsize = size / sizeof(*memnodemap);
>+
>+ return 0;
>+}
>+
> /*
> * The LSB of all start and end addresses in the node map is the value of the
> * maximum possible shift.
>@@ -99,7 +123,7 @@ static int __init extract_lsb_from_nodes
>
> for (i = 0; i < numnodes; i++) {
> spdx = paddr_to_pdx(nodes[i].start);
>- epdx = paddr_to_pdx(nodes[i].end);
>+ epdx = paddr_to_pdx(nodes[i].end - 1) + 1;
> if (spdx >= epdx)
> continue;
> bitfield |= spdx;
>@@ -108,9 +132,10 @@ static int __init extract_lsb_from_nodes
> memtop = epdx;
> }
> if (nodes_used <= 1)
>- i = 63;
>+ i = BITS_PER_LONG - 1;
> else
> i = find_first_bit(&bitfield, sizeof(unsigned long)*8);
>+ memnodemapsize = (memtop >> i) + 1;
> return i;
> }
>
>@@ -120,6 +145,10 @@ int __init compute_hash_shift(struct nod
> int shift;
>
> shift = extract_lsb_from_nodes(nodes, numnodes);
>+ if (memnodemapsize <= ARRAY_SIZE(_memnodemap))
>+ memnodemap = _memnodemap;
>+ else if (allocate_cachealigned_memnodemap())
>+ return -1;
> printk(KERN_DEBUG "NUMA: Using %d for the hash shift.\n",
> shift);
>
>@@ -233,8 +262,8 @@ void __init numa_initmem_init(unsigned l
> (u64)start_pfn << PAGE_SHIFT,
> (u64)end_pfn << PAGE_SHIFT);
> /* setup dummy node covering all memory */
>- memnode_shift = 63;
>- memnodemap[0] = 0;
>+ memnode_shift = BITS_PER_LONG - 1;
>+ memnodemap = _memnodemap;
> nodes_clear(node_online_map);
> node_set_online(0);
> for (i = 0; i < NR_CPUS; i++)
>--- 2010-01-06.orig/xen/include/asm-x86/numa.h 2010-01-06 15:16:18.000000000
>+0100
>+++ 2010-01-06/xen/include/asm-x86/numa.h 2010-01-06 15:15:41.000000000
>+0100
>@@ -25,7 +25,6 @@ extern int pxm_to_node(int nid);
>
> #define ZONE_ALIGN (1UL << (MAX_ORDER+PAGE_SHIFT))
> #define VIRTUAL_BUG_ON(x)
>-#define NODEMAPSIZE 0xfff
>
> extern void numa_add_cpu(int cpu);
> extern void numa_init_array(void);
>@@ -51,7 +50,8 @@ static inline void clear_node_cpumask(in
>
> /* Simple perfect hash to map pdx to node numbers */
> extern int memnode_shift;
>-extern u8 memnodemap[NODEMAPSIZE];
>+extern unsigned long memnodemapsize;
>+extern u8 *memnodemap;
>
> struct node_data {
> unsigned long node_start_pfn;
>@@ -64,7 +64,7 @@ extern struct node_data node_data[];
> static inline __attribute__((pure)) int phys_to_nid(paddr_t addr)
> {
> unsigned nid;
>- VIRTUAL_BUG_ON((paddr_to_pdx(addr) >> memnode_shift) >=
>NODEMAPSIZE);
>+ VIRTUAL_BUG_ON((paddr_to_pdx(addr) >> memnode_shift) >=
>memnodemapsize);
> nid = memnodemap[paddr_to_pdx(addr) >> memnode_shift];
> VIRTUAL_BUG_ON(nid >= MAX_NUMNODES || !node_data[nid]);
> return nid;
>
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