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| Started by | Anshuman Khandual <khandual@linux.vnet.ibm.com> |
|---|---|
| First post | 2017-01-30 04:40 +0100 |
| Last post | 2017-01-30 18:40 +0100 |
| Articles | 2 — 2 participants |
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[RFC V2 03/12] mm: Change generic FALLBACK zonelist creation process Anshuman Khandual <khandual@linux.vnet.ibm.com> - 2017-01-30 04:40 +0100
Re: [RFC V2 03/12] mm: Change generic FALLBACK zonelist creation process Dave Hansen <dave.hansen@intel.com> - 2017-01-30 18:40 +0100
| From | Anshuman Khandual <khandual@linux.vnet.ibm.com> |
|---|---|
| Date | 2017-01-30 04:40 +0100 |
| Subject | [RFC V2 03/12] mm: Change generic FALLBACK zonelist creation process |
| Message-ID | <t5aYV-7mm-5@gated-at.bofh.it> |
Kernel allocation to CDM node has already been prevented by putting it's
entire memory in ZONE_MOVABLE. But the CDM nodes must also be isolated
from implicit allocations happening on the system.
Any isolation seeking CDM node requires isolation from implicit memory
allocations from user space but at the same time there should also have
an explicit way to do the memory allocation.
Platform node's both zonelists are fundamental to where the memory comes
from when there is an allocation request. In order to achieve these two
objectives as stated above, zonelists building process has to change as
both zonelists (i.e FALLBACK and NOFALLBACK) gives access to the node's
memory zones during any kind of memory allocation. The following changes
are implemented in this regard.
* CDM node's zones are not part of any other node's FALLBACK zonelist
* CDM node's FALLBACK list contains it's own memory zones followed by
all system RAM zones in regular order as before
* CDM node's zones are part of it's own NOFALLBACK zonelist
These above changes ensure the following which in turn isolates the CDM
nodes as desired.
* There wont be any implicit memory allocation ending up in the CDM node
* Only __GFP_THISNODE marked allocations will come from the CDM node
* CDM node memory can be allocated through mbind(MPOL_BIND) interface
* System RAM memory will be used as fallback option in regular order in
case the CDM memory is insufficient during targted allocation request
Sample zonelist configuration:
[NODE (0)] RAM
ZONELIST_FALLBACK (0xc00000000140da00)
(0) (node 0) (DMA 0xc00000000140c000)
(1) (node 1) (DMA 0xc000000100000000)
ZONELIST_NOFALLBACK (0xc000000001411a10)
(0) (node 0) (DMA 0xc00000000140c000)
[NODE (1)] RAM
ZONELIST_FALLBACK (0xc000000100001a00)
(0) (node 1) (DMA 0xc000000100000000)
(1) (node 0) (DMA 0xc00000000140c000)
ZONELIST_NOFALLBACK (0xc000000100005a10)
(0) (node 1) (DMA 0xc000000100000000)
[NODE (2)] CDM
ZONELIST_FALLBACK (0xc000000001427700)
(0) (node 2) (Movable 0xc000000001427080)
(1) (node 0) (DMA 0xc00000000140c000)
(2) (node 1) (DMA 0xc000000100000000)
ZONELIST_NOFALLBACK (0xc00000000142b710)
(0) (node 2) (Movable 0xc000000001427080)
[NODE (3)] CDM
ZONELIST_FALLBACK (0xc000000001431400)
(0) (node 3) (Movable 0xc000000001430d80)
(1) (node 0) (DMA 0xc00000000140c000)
(2) (node 1) (DMA 0xc000000100000000)
ZONELIST_NOFALLBACK (0xc000000001435410)
(0) (node 3) (Movable 0xc000000001430d80)
[NODE (4)] CDM
ZONELIST_FALLBACK (0xc00000000143b100)
(0) (node 4) (Movable 0xc00000000143aa80)
(1) (node 0) (DMA 0xc00000000140c000)
(2) (node 1) (DMA 0xc000000100000000)
ZONELIST_NOFALLBACK (0xc00000000143f110)
(0) (node 4) (Movable 0xc00000000143aa80)
Signed-off-by: Anshuman Khandual <khandual@linux.vnet.ibm.com>
---
mm/page_alloc.c | 10 ++++++++++
1 file changed, 10 insertions(+)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index f3e0c69..5db353a 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -4825,6 +4825,16 @@ static void build_zonelists(pg_data_t *pgdat)
i = 0;
while ((node = find_next_best_node(local_node, &used_mask)) >= 0) {
+#ifdef CONFIG_COHERENT_DEVICE
+ /*
+ * CDM node's own zones should not be part of any other
+ * node's fallback zonelist but only it's own fallback
+ * zonelist.
+ */
+ if (is_cdm_node(node) && (pgdat->node_id != node))
+ continue;
+#endif
+
/*
* We don't want to pressure a particular node.
* So adding penalty to the first node in same
--
2.9.3
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| From | Dave Hansen <dave.hansen@intel.com> |
|---|---|
| Date | 2017-01-30 18:40 +0100 |
| Subject | Re: [RFC V2 03/12] mm: Change generic FALLBACK zonelist creation process |
| Message-ID | <t5o5P-6Mu-3@gated-at.bofh.it> |
| In reply to | #1569355 |
On 01/29/2017 07:35 PM, Anshuman Khandual wrote:
> * CDM node's zones are not part of any other node's FALLBACK zonelist
> * CDM node's FALLBACK list contains it's own memory zones followed by
> all system RAM zones in regular order as before
> * CDM node's zones are part of it's own NOFALLBACK zonelist
This seems like a sane policy for the system that you're describing.
But, it's still a policy, and it's rather hard-coded into the kernel.
Let's say we had a CDM node with 100x more RAM than the rest of the
system and it was just as fast as the rest of the RAM. Would we still
want it isolated like this? Or would we want a different policy?
Why do we need this hard-coded along with the cpuset stuff later in the
series. Doesn't taking a node out of the cpuset also take it out of the
fallback lists?
> while ((node = find_next_best_node(local_node, &used_mask)) >= 0) {
> +#ifdef CONFIG_COHERENT_DEVICE
> + /*
> + * CDM node's own zones should not be part of any other
> + * node's fallback zonelist but only it's own fallback
> + * zonelist.
> + */
> + if (is_cdm_node(node) && (pgdat->node_id != node))
> + continue;
> +#endif
On a superficial note: Isn't that #ifdef unnecessary? is_cdm_node() has
a 'return 0' stub when the config option is off anyway.
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