NUMA system and get_a_numa_node()

We have a system which only has one NUMA node. When trying to run ksm02 on it, becase the code calling get_allowed_nodes() with a count 2 as below:

972 /* Warning: *DO NOT* use this function in child */ 973 unsigned int get_a_numa_node(void (*cleanup_fn) (void)) 974 {
975 unsigned int nd1, nd2;
976 int ret;
977

 978         ret = get_allowed_nodes(0, 2, &nd1, &nd2);
 979         switch (ret) { 
 980         case 0:

981 break;
982 case -3:
983 tst_brkm(TCONF, cleanup_fn, "requires a NUMA system.");

it always failed with "requires a NUMA system.".

I think a NUMA system may have only one node, right? If so, could we change the count to 1?

Hi!

Quoted 13 lines

We have a system which only has one NUMA node. When trying to run ksm02 on it, becase the code calling get_allowed_nodes() with a count 2 as below:

972 /* Warning: *DO NOT* use this function in child */ 973 unsigned int get_a_numa_node(void (*cleanup_fn) (void)) 974 {
975 unsigned int nd1, nd2;
976 int ret;
977

 978         ret = get_allowed_nodes(0, 2, &nd1, &nd2);
 979         switch (ret) { 
 980         case 0:

Quoted 8 lines

981 break;
982 case -3:
983 tst_brkm(TCONF, cleanup_fn, "requires a NUMA system.");

it always failed with "requires a NUMA system.".

I think a NUMA system may have only one node, right? If so, could we change the count to 1?

Hmm, are you sure that the testcases are actually applicable to a system with only one node?

Because what the testcases do in the setup is to write 1 to /sys/kernel/mm/ksm/merge_across_nodes so I would expect that the test needs at least two nodes...

Quoted 23 lines · Cyril Hrubis

Hi!

Quoted 13 lines

We have a system which only has one NUMA node. When trying to run ksm02 on it, becase the code calling get_allowed_nodes() with a count 2 as below:

972 /* Warning: *DO NOT* use this function in child */ 973 unsigned int get_a_numa_node(void (*cleanup_fn) (void)) 974 {
975 unsigned int nd1, nd2;
976 int ret;
977

 978         ret = get_allowed_nodes(0, 2, &nd1, &nd2);
 979         switch (ret) { 
 980         case 0:

Quoted 8 lines

981 break;
982 case -3:
983 tst_brkm(TCONF, cleanup_fn, "requires a NUMA system.");

it always failed with "requires a NUMA system.".

I think a NUMA system may have only one node, right? If so, could we change the count to 1?

Quoted 7 lines

Hmm, are you sure that the testcases are actually applicable to a system with only one node?

Because what the testcases do in the setup is to write 1 to /sys/kernel/mm/ksm/merge_across_nodes so I would expect that the test needs at least two nodes...

I think if there is only one NUMA node, then this is a special case for this testcase, it'll test if set "merge_across_nodes" to 1, any problem will be triggered.

I have tried to change the node count to 1 in get_allowed_nodes() and recompiled ksm02. It works successfully.

Thanks.

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Quoted 35 lines · Han Pingtian

Quoted 23 lines · Cyril Hrubis

Hi!

Quoted 13 lines

We have a system which only has one NUMA node. When trying to run ksm02 on it, becase the code calling get_allowed_nodes() with a count 2 as below:

972 /* Warning: *DO NOT* use this function in child */ 973 unsigned int get_a_numa_node(void (*cleanup_fn) (void)) 974 {
975 unsigned int nd1, nd2;
976 int ret;
977

 978         ret = get_allowed_nodes(0, 2, &nd1, &nd2);
 979         switch (ret) { 
 980         case 0:

Quoted 8 lines

981 break;
982 case -3:
983 tst_brkm(TCONF, cleanup_fn, "requires a NUMA system.");

it always failed with "requires a NUMA system.".

I think a NUMA system may have only one node, right? If so, could we change the count to 1?

Quoted 7 lines

Hmm, are you sure that the testcases are actually applicable to a system with only one node?

Because what the testcases do in the setup is to write 1 to /sys/kernel/mm/ksm/merge_across_nodes so I would expect that the test needs at least two nodes...

I think if there is only one NUMA node, then this is a special case for this testcase, it'll test if set "merge_across_nodes" to 1, any problem will be triggered.

Quoted 3 lines

I have tried to change the node count to 1 in get_allowed_nodes() and recompiled ksm02. It works successfully.

Do you think ONLY ONE NODE can be called NUMA?

http://en.wikipedia.org/wiki/Non-uniform_memory_access

Quoted 41 lines · Wanlong Gao

Quoted 38 lines · Han Pingtian

Quoted 23 lines · Cyril Hrubis

Hi!

Quoted 13 lines

We have a system which only has one NUMA node. When trying to run ksm02 on it, becase the code calling get_allowed_nodes() with a count 2 as below:

972 /* Warning: *DO NOT* use this function in child */ 973 unsigned int get_a_numa_node(void (*cleanup_fn) (void)) 974 {
975 unsigned int nd1, nd2;
976 int ret;
977

 978         ret = get_allowed_nodes(0, 2, &nd1, &nd2);
 979         switch (ret) { 
 980         case 0:

Quoted 8 lines

981 break;
982 case -3:
983 tst_brkm(TCONF, cleanup_fn, "requires a NUMA system.");

it always failed with "requires a NUMA system.".

I think a NUMA system may have only one node, right? If so, could we change the count to 1?

Quoted 7 lines

Hmm, are you sure that the testcases are actually applicable to a system with only one node?

Because what the testcases do in the setup is to write 1 to /sys/kernel/mm/ksm/merge_across_nodes so I would expect that the test needs at least two nodes...

I think if there is only one NUMA node, then this is a special case for this testcase, it'll test if set "merge_across_nodes" to 1, any problem will be triggered.

I have tried to change the node count to 1 in get_allowed_nodes() and recompiled ksm02. It works successfully.

Quoted 4 lines

Do you think ONLY ONE NODE can be called NUMA?

http://en.wikipedia.org/wiki/Non-uniform_memory_access

I think it's not a problem to run the testcase on a non-NUMA system, if we take it as a special case?

Thanks.

------------------------------------------------------------------------------
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Quoted 4 lines · Han Pingtian

Quoted 4 lines

Do you think ONLY ONE NODE can be called NUMA?

Quoted 5 lines

Quoted 2 lines

http://en.wikipedia.org/wiki/Non-uniform_memory_access

I think it's not a problem to run the testcase on a non-NUMA system, if we take it as a special case?

It's meaningless, the "special case" you said is already there, it's ksm01.