Re: [PATCH 4/7] ppc64 - Specify amount of kernel memory at boot time

From: Mel Gorman
Date: Wed Feb 22 2006 - 11:42:01 EST

On Tue, 21 Feb 2006, Dave Hansen wrote:

On Tue, 2006-02-21 at 14:51 +0000, Mel Gorman wrote:
A new release of patches is a long time away but here is an early draft of
what the above currently looks like. Is this more or less what you were
thinking?

I think it may be a bit harder to understand than even the other
one. :(


:/

In a nutshell, get_zones_info() tries to do too much. Six function
arguments should be a big, red, warning light that something is really
wrong. Calling a function _info() is another bad sign. It means that
you can't discretely describe what it does.

Remember, there are 3 distinct tasks here:

1. size the node information from init_node_data[]
2. size the easy reclaim zone based on the boot parameters
3. take holes into account when doing the reclaim zone sizing


right

*some pounding on the keyboard*

Is this a bit clearer? It's built and boot tested on one ppc64 machine. I am having trouble finding a ppc64 machine that *has* memory holes to be 100% sure it's ok.

diff -rup -X /usr/src/patchset-0.5/bin//dontdiff linux-2.6.16-rc3-mm1-103_x86coremem/arch/powerpc/mm/numa.c linux-2.6.16-rc3-mm1-104_ppc64coremem/arch/powerpc/mm/numa.c
--- linux-2.6.16-rc3-mm1-103_x86coremem/arch/powerpc/mm/numa.c 2006-02-16 09:50:42.000000000 +0000
+++ linux-2.6.16-rc3-mm1-104_ppc64coremem/arch/powerpc/mm/numa.c 2006-02-22 16:07:35.000000000 +0000
@@ -17,10 +17,12 @@
#include <linux/nodemask.h>
#include <linux/cpu.h>
#include <linux/notifier.h>
+#include <linux/sort.h>
#include <asm/sparsemem.h>
#include <asm/lmb.h>
#include <asm/system.h>
#include <asm/smp.h>
+#include <asm/machdep.h>

static int numa_enabled = 1;

@@ -101,22 +103,41 @@ void __init add_region(unsigned int nid,
init_node_data[i].nid = nid;
}

+/* Compare two elements in init_node_data. Assume start_pfn is at start */
+static int cmp_init_node_data(const void *a, const void *b)
+{
+ return *(unsigned long *)a - *(unsigned long *)b;
+}
+
+/*
+ * init_node_data is not necessarilly in pfn order making it difficult to
+ * determine where the EasyRclm should begin if it is requested. This sorts
+ * init_node_data by start_pfn
+ */
+void __init sort_regions(void)
+{
+ size_t num = 0;
+ size_t size_element = sizeof(init_node_data) / MAX_REGIONS;
+
+ while (init_node_data[num].end_pfn)
+ num++;
+
+ sort(init_node_data, num, size_element, cmp_init_node_data, NULL);
+}
+
/* We assume init_node_data has no overlapping regions */
void __init get_region(unsigned int nid, unsigned long *start_pfn,
- unsigned long *end_pfn, unsigned long *pages_present)
+ unsigned long *end_pfn)
{
unsigned int i;

*start_pfn = -1UL;
- *end_pfn = *pages_present = 0;
+ *end_pfn = 0;

for (i = 0; init_node_data[i].end_pfn; i++) {
if (init_node_data[i].nid != nid)
continue;

- *pages_present += init_node_data[i].end_pfn -
- init_node_data[i].start_pfn;
-
if (init_node_data[i].start_pfn < *start_pfn)
*start_pfn = init_node_data[i].start_pfn;

@@ -129,6 +150,88 @@ void __init get_region(unsigned int nid,
*start_pfn = 0;
}

+/* Initialise the size of each zone in a node */
+void __init zone_sizes_init(unsigned int nid,
+ unsigned long kernelcore_pages,
+ unsigned long *zones_size)
+{
+ unsigned int i;
+ unsigned long pages_present = 0;
+
+ /* Get the number of present pages in the node */
+ for (i = 0; init_node_data[i].end_pfn; i++) {
+ if (init_node_data[i].nid != nid)
+ continue;
+
+ pages_present += init_node_data[i].end_pfn -
+ init_node_data[i].start_pfn;
+ }
+
+ if (kernelcore_pages && kernelcore_pages < pages_present) {
+ zones_size[ZONE_DMA] = kernelcore_pages;
+ zones_size[ZONE_EASYRCLM] = pages_present - kernelcore_pages;
+ } else {
+ zones_size[ZONE_DMA] = pages_present;
+ zones_size[ZONE_EASYRCLM] = 0;
+ }
+}
+
+void __init get_zholes_size(unsigned int nid, unsigned long *zones_size,
+ unsigned long *zholes_size) {
+ unsigned int i = 0;
+ unsigned int start_easyrclm_pfn;
+ unsigned long last_end_pfn, first;
+
+ /* Find where the PFN of the end of DMA is */
+ unsigned long pages_count = zones_size[ZONE_DMA];
+ for (i = 0; init_node_data[i].end_pfn; i++) {
+ unsigned long segment_size;
+ if (init_node_data[i].nid != nid)
+ continue;
+
+ /*
+ * Check if the end of ZONE_DMA is in this segment of the
+ * init_node_data
+ */
+ segment_size = init_node_data[i].end_pfn -
+ init_node_data[i].start_pfn;
+ if (pages_count > segment_size) {
+ /* End of ZONE_DMA is not here, move on */
+ pages_count -= segment_size;
+ continue;
+ }
+
+ /* End of ZONE_DMA is here */
+ start_easyrclm_pfn = init_node_data[i].start_pfn + pages_count;
+ break;
+ }
+
+ /* Walk the map again and get the size of the holes */
+ first = 1;
+ zholes_size[ZONE_DMA] = 0;
+ zholes_size[ZONE_EASYRCLM] = 0;
+ for (i = 1; init_node_data[i].end_pfn; i++) {
+ unsigned long hole_size;
+ if (init_node_data[i].nid != nid)
+ continue;
+
+ if (first) {
+ last_end_pfn = init_node_data[i].end_pfn;
+ first = 0;
+ continue;
+ }
+
+ /* Hole found */
+ hole_size = init_node_data[i].start_pfn - last_end_pfn;
+ if (init_node_data[i].start_pfn < start_easyrclm_pfn) {
+ zholes_size[ZONE_DMA] += hole_size;
+ } else {
+ zholes_size[ZONE_EASYRCLM] += hole_size;
+ }
+ last_end_pfn = init_node_data[i].end_pfn;
+ }
+}
+
static inline void map_cpu_to_node(int cpu, int node)
{
numa_cpu_lookup_table[cpu] = node;
@@ -622,11 +725,11 @@ void __init do_init_bootmem(void)
register_cpu_notifier(&ppc64_numa_nb);

for_each_online_node(nid) {
- unsigned long start_pfn, end_pfn, pages_present;
+ unsigned long start_pfn, end_pfn;
unsigned long bootmem_paddr;
unsigned long bootmap_pages;

- get_region(nid, &start_pfn, &end_pfn, &pages_present);
+ get_region(nid, &start_pfn, &end_pfn);

/* Allocate the node structure node local if possible */
NODE_DATA(nid) = careful_allocation(nid,
@@ -721,21 +824,36 @@ void __init paging_init(void)
{
unsigned long zones_size[MAX_NR_ZONES];
unsigned long zholes_size[MAX_NR_ZONES];
+ unsigned long kernelcore_pages = 0;
int nid;
+ char *opt;

memset(zones_size, 0, sizeof(zones_size));
memset(zholes_size, 0, sizeof(zholes_size));

- for_each_online_node(nid) {
- unsigned long start_pfn, end_pfn, pages_present;
-
- get_region(nid, &start_pfn, &end_pfn, &pages_present);
+ /* Check if ZONE_EASYRCLM should be populated */
+ opt = strstr(cmd_line, "kernelcore=");
+ if (opt) {
+ opt += 11;
+ unsigned long size_bytes = memparse(opt, &opt);
+ kernelcore_pages = size_bytes >> PAGE_SHIFT;
+ }

- zones_size[ZONE_DMA] = end_pfn - start_pfn;
- zholes_size[ZONE_DMA] = zones_size[ZONE_DMA] - pages_present;
+ sort_regions();
+ for_each_online_node(nid) {
+ unsigned long start_pfn, end_region_pfn;

- dbg("free_area_init node %d %lx %lx (hole: %lx)\n", nid,
- zones_size[ZONE_DMA], start_pfn, zholes_size[ZONE_DMA]);
+ get_region(nid, &start_pfn, &end_region_pfn);
+ zone_sizes_init(nid, kernelcore_pages, &zones_size[0]);
+ get_zholes_size(nid, &zones_size[0], &zholes_size[0]);
+
+ dbg("free_area_init DMA node %d %lx %lx (hole: %lx)\n",
+ nid, zones_size[ZONE_DMA],
+ start_pfn, zholes_size[ZONE_DMA]);
+
+ dbg("free_area_init EasyRclm node %d %lx %lx (hole: %lx)\n",
+ nid, zones_size[ZONE_EASYRCLM],
+ start_pfn, zholes_size[ZONE_EASYRCLM]);

free_area_init_node(nid, NODE_DATA(nid), zones_size, start_pfn,
zholes_size);
-
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