7c243c7168
When booting on a large memory system, the kernel spends considerable time in memmap_init_zone() setting up memory zones. Analysis shows significant time spent in __early_pfn_to_nid(). The routine memmap_init_zone() checks each PFN to verify the nid is valid. __early_pfn_to_nid() sequentially scans the list of pfn ranges to find the right range and returns the nid. This does not scale well. On a 4 TB (single rack) system there are 308 memory ranges to scan. The higher the PFN the more time spent sequentially spinning through memory ranges. Since memmap_init_zone() increments pfn, it will almost always be looking for the same range as the previous pfn, so check that range first. If it is in the same range, return that nid. If not, scan the list as before. A 4 TB (single rack) UV1 system takes 512 seconds to get through the zone code. This performance optimization reduces the time by 189 seconds, a 36% improvement. A 2 TB (single rack) UV2 system goes from 212.7 seconds to 99.8 seconds, a 112.9 second (53%) reduction. [akpm@linux-foundation.org: make the statics __meminitdata] [akpm@linux-foundation.org: fix comment formatting] [akpm@linux-foundation.org: fix ia64, per yinghai] [akpm@linux-foundation.org: add missing semicolon, per Tony] Signed-off-by: Russ Anderson <rja@sgi.com> Cc: David Rientjes <rientjes@google.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Tested-by: "Luck, Tony" <tony.luck@intel.com> Cc: Yinghai Lu <yinghai@kernel.org> Cc: Lin Feng <linfeng@cn.fujitsu.com> Cc: KOSAKI Motohiro <kosaki.motohiro@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
110 lines
3 KiB
C
110 lines
3 KiB
C
/*
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* This file is subject to the terms and conditions of the GNU General Public
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* License. See the file "COPYING" in the main directory of this archive
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* for more details.
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*
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* This file contains NUMA specific variables and functions which can
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* be split away from DISCONTIGMEM and are used on NUMA machines with
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* contiguous memory.
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*
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* 2002/08/07 Erich Focht <efocht@ess.nec.de>
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*/
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#include <linux/cpu.h>
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#include <linux/kernel.h>
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#include <linux/mm.h>
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#include <linux/node.h>
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#include <linux/init.h>
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#include <linux/bootmem.h>
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#include <linux/module.h>
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#include <asm/mmzone.h>
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#include <asm/numa.h>
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/*
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* The following structures are usually initialized by ACPI or
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* similar mechanisms and describe the NUMA characteristics of the machine.
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*/
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int num_node_memblks;
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struct node_memblk_s node_memblk[NR_NODE_MEMBLKS];
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struct node_cpuid_s node_cpuid[NR_CPUS] =
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{ [0 ... NR_CPUS-1] = { .phys_id = 0, .nid = NUMA_NO_NODE } };
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/*
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* This is a matrix with "distances" between nodes, they should be
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* proportional to the memory access latency ratios.
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*/
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u8 numa_slit[MAX_NUMNODES * MAX_NUMNODES];
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/* Identify which cnode a physical address resides on */
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int
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paddr_to_nid(unsigned long paddr)
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{
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int i;
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for (i = 0; i < num_node_memblks; i++)
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if (paddr >= node_memblk[i].start_paddr &&
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paddr < node_memblk[i].start_paddr + node_memblk[i].size)
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break;
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return (i < num_node_memblks) ? node_memblk[i].nid : (num_node_memblks ? -1 : 0);
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}
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#if defined(CONFIG_SPARSEMEM) && defined(CONFIG_NUMA)
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/*
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* Because of holes evaluate on section limits.
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* If the section of memory exists, then return the node where the section
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* resides. Otherwise return node 0 as the default. This is used by
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* SPARSEMEM to allocate the SPARSEMEM sectionmap on the NUMA node where
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* the section resides.
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*/
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int __meminit __early_pfn_to_nid(unsigned long pfn)
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{
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int i, section = pfn >> PFN_SECTION_SHIFT, ssec, esec;
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/*
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* NOTE: The following SMP-unsafe globals are only used early in boot
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* when the kernel is running single-threaded.
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*/
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static int __meminitdata last_ssec, last_esec;
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static int __meminitdata last_nid;
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if (section >= last_ssec && section < last_esec)
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return last_nid;
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for (i = 0; i < num_node_memblks; i++) {
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ssec = node_memblk[i].start_paddr >> PA_SECTION_SHIFT;
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esec = (node_memblk[i].start_paddr + node_memblk[i].size +
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((1L << PA_SECTION_SHIFT) - 1)) >> PA_SECTION_SHIFT;
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if (section >= ssec && section < esec) {
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last_ssec = ssec;
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last_esec = esec;
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last_nid = node_memblk[i].nid;
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return node_memblk[i].nid;
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}
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}
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return -1;
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}
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void __cpuinit numa_clear_node(int cpu)
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{
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unmap_cpu_from_node(cpu, NUMA_NO_NODE);
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}
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#ifdef CONFIG_MEMORY_HOTPLUG
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/*
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* SRAT information is stored in node_memblk[], then we can use SRAT
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* information at memory-hot-add if necessary.
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*/
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int memory_add_physaddr_to_nid(u64 addr)
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{
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int nid = paddr_to_nid(addr);
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if (nid < 0)
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return 0;
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return nid;
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}
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EXPORT_SYMBOL_GPL(memory_add_physaddr_to_nid);
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#endif
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#endif
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