(CC:ed linux-mm)
On Thu, Apr 10, 2014 at 03:06:49PM -0700, David Rientjes wrote:
> On Wed, 9 Apr 2014, Naoya Horiguchi wrote:
>
> > > [ And that block_size_bytes file is absolutely horrid, why are we
> > > exporting all this information in hex and not telling anybody? ]
> >
> > Indeed, this kind of implicit hex numbers are commonly used in many place.
> > I guess that it's maybe for historical reasons.
> >
>
> I think it was meant to be simple to that you could easily add the length
> to the start, but it should at least prefix this with `0x'. That code has
> been around for years, though, so we probably can't fix it now.
>
> > > I'd much prefer a single change that works for everybody and userspace can
> > > rely on exporting accurate information as long as sysfs is mounted, and
> > > not even need to rely on getpagesize() to convert from pfn to physical
> > > address: just simple {start,end}_phys_addr files added to
> > > /sys/devices/system/node/nodeN/ for node N. Online information can
> > > already be parsed for these ranges from /sys/devices/system/node/online.
> >
> > OK, so what if some node has multiple address ranges? I don't think that
> > start(end)_phys_addr simply returns minimum (maximum) possible address is optimal,
> > because users can't know about void range between valid address ranges
> > (non-exist pfn should not belong to any node).
> > Are printing multilined (or comma-separated) ranges preferable for example
> > like below?
> >
> > $ cat /sys/devices/system/node/nodeN/phys_addr
> > 0x0-0x80000000
> > 0x100000000-0x180000000
> >
>
> What the...? nodeN should represent the pgdat for that node and a pgdat
> can only have a single range.
Yes, that's right, but it seems to me that just node_start_pfn and node_end_pfn
is not enough because there can be holes (without any page struct backed) inside
[node_start_pfn, node_end_pfn), and it's not aware of memory hotplug.
> I'm suggesting that
> /sys/devices/system/node/nodeN/start_phys_addr returns
> node_start_pfn(N) << PAGE_SHIFT and
> /sys/devices/system/node/nodeN/end_phys_addr returns
> node_end_pfn(N) << PAGE_SHIFT and prefix them correctly this time with
> `0x'.
Yes, we should have '0x' prefix for new interfaces.
I wrote a patch, so could you take a look?
I tested !CONFIG_MEMORY_HOTPLUG_SPARSE case too, and it works fine.
Thanks,
Naoya Horiguchi
---
From: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
Date: Thu, 10 Apr 2014 20:59:59 -0400
Subject: [PATCH] drivers/base/node.c: export physical address range of given
node
Userspace applications sometimes want to know which node a give page belongs to,
so this patch adds a new interface /sys/devices/system/node/nodeN/phys_addr
which gives the physical address ranges of node N. A reader gets multilined
physical address ranges backed by valid pfn (neither holes within the zone nor
offlined range are not included in the output.)
Here is the example.
# cat /sys/devices/system/node/node0/phys_addr
0x1000-0x40000000
# cat /sys/devices/system/node/node3/phys_addr
0xc0000000-0xe0000000
0x100000000-0x120000000
# echo offline > /sys/devices/system/memory/memory33/state
# cat /sys/devices/system/node/node3/phys_addr
0xc0000000-0xe0000000
0x100000000-0x108000000
0x110000000-0x120000000
Signed-off-by: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
---
drivers/base/node.c | 60 ++++++++++++++++++++++++++++++++++++++++++++++++++
include/linux/memory.h | 4 ++++
include/linux/mmzone.h | 1 +
3 files changed, 65 insertions(+)
diff --git a/drivers/base/node.c b/drivers/base/node.c
index bc9f43bf7e29..21e87909ec4f 100644
--- a/drivers/base/node.c
+++ b/drivers/base/node.c
@@ -18,6 +18,7 @@
#include <linux/device.h>
#include <linux/swap.h>
#include <linux/slab.h>
+#include <linux/memblock.h>
static struct bus_type node_subsys = {
.name = "node",
@@ -185,6 +186,64 @@ static ssize_t node_read_vmstat(struct device *dev,
}
static DEVICE_ATTR(vmstat, S_IRUGO, node_read_vmstat, NULL);
+#ifdef CONFIG_MEMORY_HOTPLUG_SPARSE
+static bool valid_mem_section(unsigned long sec_nr)
+{
+ struct memory_block *memblk;
+ if (!present_section_nr(sec_nr))
+ return false;
+ memblk = find_memory_block(__nr_to_section(sec_nr));
+ if (!memblk || is_memblock_offlined(memblk))
+ return false;
+ return true;
+}
+#endif
+
+static ssize_t node_read_phys_addr(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ struct pglist_data *pgdat = NODE_DATA(dev->id);
+ unsigned long start, end;
+ int n = 0;
+ unsigned long pfn;
+ unsigned long rstart = 0, rend = 0; /* range's start and end */
+
+ start = pgdat->node_start_pfn;
+ end = pgdat_end_pfn(pgdat);
+ pfn = start;
+ while (pfn < end) {
+#ifdef CONFIG_MEMORY_HOTPLUG_SPARSE
+ if (unlikely(!valid_mem_section(pfn_to_section_nr(pfn)))) {
+ if (rstart) {
+ n += sprintf(buf + n, "0x%llx-0x%llx\n",
+ PFN_PHYS(rstart), PFN_PHYS(rend));
+ rstart = 0;
+ rend = 0;
+ }
+ pfn = SECTION_NEXT_BOUNDARY(pfn);
+ continue;
+ }
+#endif
+ if (pfn_valid(pfn)) {
+ if (!rstart)
+ rstart = pfn;
+ rend = pfn + 1;
+ } else {
+ if (rstart)
+ n += sprintf(buf + n, "0x%llx-0x%llx\n",
+ PFN_PHYS(rstart), PFN_PHYS(rend));
+ rstart = 0;
+ rend = 0;
+ }
+ pfn++;
+ }
+ if (rstart)
+ n += sprintf(buf + n, "0x%llx-0x%llx\n",
+ PFN_PHYS(rstart), PFN_PHYS(rend));
+ return n;
+}
+static DEVICE_ATTR(phys_addr, S_IRUGO, node_read_phys_addr, NULL);
+
static ssize_t node_read_distance(struct device *dev,
struct device_attribute *attr, char * buf)
{
@@ -288,6 +347,7 @@ static int register_node(struct node *node, int num, struct node *parent)
device_create_file(&node->dev, &dev_attr_numastat);
device_create_file(&node->dev, &dev_attr_distance);
device_create_file(&node->dev, &dev_attr_vmstat);
+ device_create_file(&node->dev, &dev_attr_phys_addr);
scan_unevictable_register_node(node);
diff --git a/include/linux/memory.h b/include/linux/memory.h
index bb7384e3c3d8..b68e14f8818c 100644
--- a/include/linux/memory.h
+++ b/include/linux/memory.h
@@ -103,6 +103,10 @@ static inline int memory_isolate_notify(unsigned long val, void *v)
{
return 0;
}
+static inline struct memory_block *find_memory_block(struct mem_section *ms)
+{
+ return NULL;
+}
#else
extern int register_memory_notifier(struct notifier_block *nb);
extern void unregister_memory_notifier(struct notifier_block *nb);
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 9b61b9bf81ac..138a7a6684ab 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -1084,6 +1084,7 @@ static inline unsigned long early_pfn_to_nid(unsigned long pfn)
#define SECTION_ALIGN_UP(pfn) (((pfn) + PAGES_PER_SECTION - 1) & PAGE_SECTION_MASK)
#define SECTION_ALIGN_DOWN(pfn) ((pfn) & PAGE_SECTION_MASK)
+#define SECTION_NEXT_BOUNDARY(pfn) (SECTION_ALIGN_DOWN(pfn) + PAGES_PER_SECTION)
struct page;
struct page_cgroup;
--
1.9.0
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