UseNUMA membind Issue in openJDK

Swati Sharma swatibits14 at gmail.com
Mon Jun 11 10:00:56 UTC 2018


Hi Gustavo,

May be you can remove the method "numa_bitmask_nbytes" as it's not getting
used.
I am ok with the changes,If Derek confirms we can go ahead.

My name is there on the page "Swati Sharma - OpenJDK" , I have already
signed the OCA on individual basis.

Thanks,
Swati

On Sat, Jun 9, 2018 at 5:06 AM, Gustavo Romero <gromero at linux.vnet.ibm.com>
wrote:

> Hi Swati,
>
> Sorry, as usual I had to reserve a machine before trying it.
>
> I wanted to test it against a POWER9 with a NVIDIA Tesla V100 device
> attached.
>
> On such a machines numa nodes are quite sparse so I thought it would not
> be bad
> to check against them:
>
> available: 8 nodes (0,8,250-255)
> node 0 cpus: 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23
> 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48
> 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63
> node 0 size: 261693 MB
> node 0 free: 233982 MB
> node 8 cpus: 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83
> 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106
> 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125
> 126 127
> node 8 size: 261748 MB
> node 8 free: 257078 MB
> node 250 cpus:
> node 250 size: 0 MB
> node 250 free: 0 MB
> node 251 cpus:
> node 251 size: 0 MB
> node 251 free: 0 MB
> node 252 cpus:
> node 252 size: 15360 MB
> node 252 free: 15360 MB
> node 253 cpus:
> node 253 size: 0 MB
> node 253 free: 0 MB
> node 254 cpus:
> node 254 size: 0 MB
> node 254 free: 0 MB
> node 255 cpus:
> node 255 size: 15360 MB
> node 255 free: 15360 MB
> node distances:
> node   0   8  250  251  252  253  254  255
>   0:  10  40  80  80  80  80  80  80
>   8:  40  10  80  80  80  80  80  80
>  250:  80  80  10  80  80  80  80  80
>  251:  80  80  80  10  80  80  80  80
>  252:  80  80  80  80  10  80  80  80
>  253:  80  80  80  80  80  10  80  80
>  254:  80  80  80  80  80  80  10  80
>  255:  80  80  80  80  80  80  80  10
>
>
> Please, find my comments below, inlined.
>
> On 06/01/2018 08:10 AM, Swati Sharma wrote:
>
>> I will fix the thread binding issue in a separate patch.
>>
>
> I would like to address it in this change. I think it's not good to leave
> such a
> "dangling" behavior for the cpus once the memory bind issue is addressed.
>
> I suggest the following simple check to fix it (in accordance to what we've
> discussed previously, i.e. remap cpu/node considering configuration, bind,
> and
> distance in  rebuild_cpu_to_node_map():
>
> -    if (!isnode_in_configured_nodes(nindex_to_node()->at(i))) {
> +    if (!isnode_in_configured_nodes(nindex_to_node()->at(i)) ||
> +        !isnode_in_bound_nodes(nindex_to_node()->at(i))) {
>        closest_distance = INT_MAX;
> ...
>        for (size_t m = 0; m < node_num; m++) {
> -        if (m != i && isnode_in_configured_nodes(nindex_to_node()->at(m)))
> {
> +        if (m != i &&
> +            isnode_in_configured_nodes(nindex_to_node()->at(m)) &&
> +            isnode_in_bound_nodes(nindex_to_node()->at(m))) {
>
> I tested it against the aforementioned topology and against the following
> one:
>
> available: 4 nodes (0-3)
> node 0 cpus: 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23
> 24 25 26 27 28 29 30 31
> node 0 size: 55685 MB
> node 0 free: 53196 MB
> node 1 cpus: 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51
> 52 53 54 55 56 57 58 59 60 61 62 63
> node 1 size: 53961 MB
> node 1 free: 49795 MB
> node 2 cpus:
> node 2 size: 21231 MB
> node 2 free: 21171 MB
> node 3 cpus:
> node 3 size: 22492 MB
> node 3 free: 22432 MB
> node distances:
> node   0   1   2   3
>   0:  10  20  40  40
>   1:  20  10  40  40
>   2:  40  40  10  20
>   3:  40  40  20  10
>
>
>
>> Updated the previous patch by removing the structure and using the methods
>> provided by numa API.Here is the updated one with the changes(attached
>> also).
>>
>
> Thanks.
>
>
> ========================PATCH=========================
>> diff --git a/src/hotspot/os/linux/os_linux.cpp
>> b/src/hotspot/os/linux/os_linux.cpp
>> --- a/src/hotspot/os/linux/os_linux.cpp
>> +++ b/src/hotspot/os/linux/os_linux.cpp
>>
>
> ...
>
> @@ -4962,8 +4972,9 @@
>>       if (!Linux::libnuma_init()) {
>>         UseNUMA = false;
>>       } else {
>> -      if ((Linux::numa_max_node() < 1)) {
>> -        // There's only one node(they start from 0), disable NUMA.
>> +      if ((Linux::numa_max_node() < 1) || Linux::isbound_to_single_node())
>> {
>> +        // If there's only one node(they start from 0) or if the process
>>
>                                       ^ let's fix this missing space
>
> ...
>
>
> +  // Check if bound to only one numa node.
>> +  // Returns true if bound to a single numa node, otherwise returns
>> false.
>> +  static bool isbound_to_single_node() {
>> +    int single_node = 0;
>> +    struct bitmask* bmp = NULL;
>> +    unsigned int node = 0;
>> +    unsigned int max_number_of_nodes = 0;
>> +    if (_numa_get_membind != NULL && _numa_bitmask_nbytes != NULL) {
>> +      bmp = _numa_get_membind();
>> +      max_number_of_nodes = _numa_bitmask_nbytes(bmp) * 8;
>> +    } else {
>> +      return false;
>> +    }
>> +    for (node = 0; node < max_number_of_nodes; node++) {
>> +       if (_numa_bitmask_isbitset(bmp, node)) {
>> +         single_node++;
>> +         if (single_node == 2) {
>> +           return false;
>> +         }
>> +       }
>> +    }
>> +    if (single_node == 1) {
>> +      return true;
>> +    } else {
>> +      return false;
>> +    }
>> +  }
>>
>
> Now that numa_bitmask_isbitset() is being used (instead of the previous
> version
> that iterated through an array of longs, I suggest to tweak it a bit,
> removing
> the if (single_node == 2) check.
>
> I don't think removing it will hurt. In fact, numa_bitmask_nbytes()
> returns the
> total amount of bytes the bitmask can hold. However the total number of
> nodes in
> the system is usually much smaller than numa_bitmask_nbytes() * 8.
>
> So for a x86_64 system like that with only 2 numa nodes:
>
> available: 2 nodes (0-1)
> node 0 cpus: 0 1 2 3 4 5 6 7 16 17 18 19 20 21 22 23
> node 0 size: 131018 MB
> node 0 free: 101646 MB
> node 1 cpus: 8 9 10 11 12 13 14 15 24 25 26 27 28 29 30 31
> node 1 size: 98304 MB
> node 1 free: 91692 MB
> node distances:
> node   0   1
>   0:  10  11
>   1:  11  10
>
> numa_bitmask_nbytes(): 64 =>  max_number_of_node = 512
> numa_max_node(): 1 => 1 + 1 iterations
>
> and the value returned by numa_bitmask_nbytes() does not change for
> different
> bind configurations. It's fixed. Another example is that on Power with 4
> numa
> nodes:
>
> available: 4 nodes (0-1,16-17)
> node 0 cpus: 0 8 16 24 32
> node 0 size: 130722 MB
> node 0 free: 71930 MB
> node 1 cpus: 40 48 56 64 72
> node 1 size: 0 MB
> node 1 free: 0 MB
> node 16 cpus: 80 88 96 104 112
> node 16 size: 130599 MB
> node 16 free: 75934 MB
> node 17 cpus: 120 128 136 144 152
> node 17 size: 0 MB
> node 17 free: 0 MB
> node distances:
> node   0   1  16  17
>   0:  10  20  40  40
>   1:  20  10  40  40
>  16:  40  40  10  20
>  17:  40  40  20  10
>
> numa_bitmask_nbytes(): 32 => max_number_of_node = 256
> numa_max_node(): 17 => 17 + 1 iterations
>
> So I understand it's better to set the iteration over numa_max_node()
> instead of
> numa_bitmask_nbytes(). Even more for Intel (with contiguous nodes) than for
> Power.
>
> For the POWER9 with NVIDIA Tesla it would be a worst case: only 8 numa
> nodes but
> numa_max_node is 255! But I understand it's a very rare case and I'm fine
> with
> that.
>
> So what about:
>
> +    if (_numa_get_membind != NULL && _numa_max_node != NULL) {
> +      bmp = _numa_get_membind();
> +      highest_node_number = _numa_max_node();
> +    } else {
> +      return false;
> +    }
> +
> +    for (node = 0; node <= highest_node_number; node++) {
> +      if (_numa_bitmask_isbitset(bmp, node)) {
> +        nodes++;
> +      }
> +    }
> +
> +    if (nodes == 1) {
> +      return true;
> +    } else {
> +      return false;
> +    }
>
> For convenience, I hosted a patch with all the changes above here:
> http://cr.openjdk.java.net/~gromero/8189922/draft/usenuma_v4.patch
>
> @Derek, could you please confirm that this change solves JDK-8189922?
>
> Swati, if Derek confirms it solves JDK-8189922? and you confirm it's fine
> for
> you I'll consider it's reviewed from my side and I can host that change
> for you
> so you can start a formal request for approval (remember I'm not a
> Reviewer, so
> you still need two additional reviews for the change).
>
> Finally, as a heads up, I could not find you (nor AMD?) in the OCA:
>
> http://www.oracle.com/technetwork/community/oca-486395.html#a
>
> If I'm not mistaken, you (individually) or AMD must sign it before
> contributing
> to OpenJDK.
>
>
> Best regards,
> Gustavo
>
>
> =======================================================
>>
>> Swati
>>
>>
>>
>>
>> On Tue, May 29, 2018 at 6:53 PM, Gustavo Romero <
>> gromero at linux.vnet.ibm.com <mailto:gromero at linux.vnet.ibm.com>> wrote:
>>  >
>>  > Hi Swati,
>>  >
>>  > On 05/29/2018 06:12 AM, Swati Sharma wrote:
>>  >>
>>  >> I have incorporated some changes suggested by you.
>>  >>
>>  >> The use of struct bitmask's  maskp for checking 64 bit in single
>> iteration
>>  >> is more optimized compared to numa_bitmask_isbitset()  as by using
>> this we
>>  >> need to check each bit for  1024 times(SUSE case) and 64 times(Ubuntu
>> Case).
>>  >> If its fine to iterate at initialization time then I can change.
>>  >
>>  >
>>  > Yes, I know, your version is more optimized. libnuma API should
>> provide a
>>  > ready-made solution for that... but that's another story. I'm curious
>> to know
>>  > what the time difference is on the worst case for both ways tho.
>> Anyway, I
>>  > just would like to point out that, regardless performance, it's
>> possible to
>>  > achieve the same result with current libnuma API.
>>  >
>>  >
>>  >> For the answer to your question:
>>  >> If it picks up node 16, not so bad, but what if it picks up node 0 or
>> 1?
>>  >> It can be checked based on numa_distance instead of picking up the
>> lgrps randomly.
>>  >
>>  >
>>  > That seems a good solution. You can do the checking very early, so
>>  > lgrp_spaces()->find() does not even fail (return -1), i.e. by changing
>> the CPU to
>>  > node mapping on initialization (avoiding to change cas_allocate()). On
>> that checking
>>  > both numa distance and if the node is bound (or not) would be
>> considered to generate
>>  > the map.
>>  >
>>  >
>>  > Best regards,
>>  > Gustavo
>>  >
>>  >> Thanks,
>>  >> Swati
>>  >>
>>  >>
>>  >>
>>  >> On Fri, May 25, 2018 at 4:54 AM, Gustavo Romero <
>> gromero at linux.vnet.ibm.com <mailto:gromero at linux.vnet.ibm.com> <mailto:
>> gromero at linux.vnet.ibm.com <mailto:gromero at linux.vnet.ibm.com>>> wrote:
>>  >>
>>  >>     Hi Swati,
>>  >>
>>  >>
>>  >>     Thanks for CC:ing me. Sorry for the delay replying it, I had to
>> reserve a few
>>  >>     specific machines before trying your patch :-)
>>  >>
>>  >>     I think that UseNUMA's original task was to figure out the best
>> binding
>>  >>     setup for the JVM automatically but I understand that it also has
>> to be aware
>>  >>     that sometimes, for some (new) particular reasons, its binding
>> task is
>>  >>     "modulated" by other external agents. Thanks for proposing a fix.
>>  >>
>>  >>     I have just a question/concern on the proposal: how the JVM
>> should behave if
>>  >>     CPUs are not bound in accordance to the bound memory nodes? For
>> instance, what
>>  >>     happens if no '--cpunodebind' is passed and '--membind=0,1,16' is
>> passed at
>>  >>     the same time on this numa topology:
>>  >>
>>  >>     brianh at p215n12:~$ numactl -H
>>  >>     available: 4 nodes (0-1,16-17)
>>  >>     node 0 cpus: 0 1 2 3 8 9 10 11 16 17 18 19 24 25 26 27 32 33 34 35
>>  >>     node 0 size: 65342 MB
>>  >>     node 0 free: 56902 MB
>>  >>     node 1 cpus: 40 41 42 43 48 49 50 51 56 57 58 59 64 65 66 67 72
>> 73 74 75
>>  >>     node 1 size: 65447 MB
>>  >>     node 1 free: 58322 MB
>>  >>     node 16 cpus: 80 81 82 83 88 89 90 91 96 97 98 99 104 105 106 107
>> 112 113 114 115
>>  >>     node 16 size: 65448 MB
>>  >>     node 16 free: 63096 MB
>>  >>     node 17 cpus: 120 121 122 123 128 129 130 131 136 137 138 139 144
>> 145 146 147 152 153 154 155
>>  >>     node 17 size: 65175 MB
>>  >>     node 17 free: 61522 MB
>>  >>     node distances:
>>  >>     node   0   1  16  17
>>  >>        0:  10  20  40  40
>>  >>        1:  20  10  40  40
>>  >>       16:  40  40  10  20
>>  >>       17:  40  40  20  10
>>  >>
>>  >>
>>  >>     In that case JVM will spawn threads that will run on all CPUs,
>> including those
>>  >>     CPUs in numa node 17. Then once in
>>  >>     src/hotspot/share/gc/parallel/mutableNUMASpace.cpp, in
>> cas_allocate():
>>  >>
>>  >>       834 // This version is lock-free.
>>  >>       835 HeapWord* MutableNUMASpace::cas_allocate(size_t size) {
>>  >>       836   Thread* thr = Thread::current();
>>  >>       837   int lgrp_id = thr->lgrp_id();
>>  >>       838   if (lgrp_id == -1 || !os::numa_has_group_homing()) {
>>  >>       839     lgrp_id = os::numa_get_group_id();
>>  >>       840     thr->set_lgrp_id(lgrp_id);
>>  >>       841   }
>>  >>
>>  >>     a newly created thread will try to be mapped to a numa node given
>> your CPU ID.
>>  >>     So if that CPU is in numa node 17 it will then not find it in:
>>  >>
>>  >>       843   int i = lgrp_spaces()->find(&lgrp_id, LGRPSpace::equals);
>>  >>
>>  >>     and will fallback to a random map, picking up a random numa node
>> among nodes
>>  >>     0, 1, and 16:
>>  >>
>>  >>       846   if (i == -1) {
>>  >>       847     i = os::random() % lgrp_spaces()->length();
>>  >>       848   }
>>  >>
>>  >>     If it picks up node 16, not so bad, but what if it picks up node
>> 0 or 1?
>>  >>
>>  >>     I see that if one binds mem but leaves CPU unbound one has to
>> know exactly what
>>  >>     she/he is doing, because it can be likely suboptimal. On the
>> other hand, letting
>>  >>     the node being picked up randomly when there are memory nodes
>> bound but no CPUs
>>  >>     seems even more suboptimal in some scenarios. Thus, should the
>> JVM deal with it?
>>  >>
>>  >>     @Zhengyu, do you have any opinion on that?
>>  >>
>>  >>     Please find a few nits / comments inline.
>>  >>
>>  >>     Note that I'm not a (R)eviewer so you still need two official
>> reviews.
>>  >>
>>  >>
>>  >>     Best regards,
>>  >>     Gustavo
>>  >>
>>  >>     On 05/21/2018 01:44 PM, Swati Sharma wrote:
>>  >>
>>  >>         ======================PATCH==============================
>>  >>         diff --git a/src/hotspot/os/linux/os_linux.cpp
>> b/src/hotspot/os/linux/os_linux.cpp
>>  >>         --- a/src/hotspot/os/linux/os_linux.cpp
>>  >>         +++ b/src/hotspot/os/linux/os_linux.cpp
>>  >>         @@ -2832,14 +2832,42 @@
>>  >>              // Map all node ids in which is possible to allocate
>> memory. Also nodes are
>>  >>              // not always consecutively available, i.e. available
>> from 0 to the highest
>>  >>              // node number.
>>  >>         +  // If the nodes have been bound explicitly using numactl
>> membind, then
>>  >>         +  // allocate memory from those nodes only.
>>  >>
>>  >>
>>  >>     I think ok to place that comment on the same existing line, like:
>>  >>
>>  >>     -  // node number.
>>  >>     +  // node number. If the nodes have been bound explicitly using
>> numactl membind,
>>  >>     +  // then allocate memory from these nodes only.
>>  >>
>>  >>
>>  >>              for (size_t node = 0; node <= highest_node_number;
>> node++) {
>>  >>         -    if (Linux::isnode_in_configured_nodes(node)) {
>>  >>         +    if (Linux::isnode_in_bounded_nodes(node)) {
>>  >>
>>  >>     ---------------------------------^ s/bounded/bound/
>>  >>
>>  >>
>>  >>                  ids[i++] = node;
>>  >>                }
>>  >>              }
>>  >>              return i;
>>  >>            }
>>  >>         +extern "C"  struct bitmask {
>>  >>         +  unsigned long size; /* number of bits in the map */
>>  >>         +  unsigned long *maskp;
>>  >>         +};
>>  >>
>>  >>
>>  >>     I think it's possible to move the function below to os_linux.hpp
>> with its
>>  >>     friends and cope with the forward declaration of 'struct
>> bitmask*` by using the
>>  >>     functions from numa API, notably numa_bitmask_nbytes() and
>>  >>     numa_bitmask_isbitset() only,  avoiding the member dereferecing
>> issue and the
>>  >>     need to add the above struct explicitly.
>>  >>
>>  >>
>>  >>         +// Check if single memory node bound.
>>  >>         +// Returns true if single memory node bound.
>>  >>
>>  >>
>>  >>     I suggest a minuscule improvement, something like:
>>  >>
>>  >>     +// Check if bound to only one numa node.
>>  >>     +// Returns true if bound to a single numa node, otherwise
>> returns false.
>>  >>
>>  >>
>>  >>         +bool os::Linux::issingle_node_bound() {
>>  >>
>>  >>
>>  >>     What about s/issingle_node_bound/isbound_to_single_node/ ?
>>  >>
>>  >>
>>  >>         +  struct bitmask* bmp = _numa_get_membind != NULL ?
>> _numa_get_membind() : NULL;
>>  >>         +  if(!(bmp != NULL && bmp->maskp != NULL)) return false;
>>  >>
>>  >>                                -----^
>>  >>     Are you sure this checking is necessary? I think if
>> numa_get_membind succeed
>>  >>     bmp->maskp is always != NULL.
>>  >>
>>  >>     Indentation here is odd. No space before 'if' and return on the
>> same line.
>>  >>
>>  >>     I would try to avoid lines over 80 chars.
>>  >>
>>  >>
>>  >>         +  int issingle = 0;
>>  >>         +  // System can have more than 64 nodes so check in all the
>> elements of
>>  >>         +  // unsigned long array
>>  >>         +  for (unsigned long i = 0; i < (bmp->size / (8 *
>> sizeof(unsigned long))); i++) {
>>  >>         +    if (bmp->maskp[i] == 0) {
>>  >>         +      continue;
>>  >>         +    } else if ((bmp->maskp[i] & (bmp->maskp[i] - 1)) == 0) {
>>  >>         +      issingle++;
>>  >>         +    } else {
>>  >>         +      return false;
>>  >>         +    }
>>  >>         +  }
>>  >>         +  if (issingle == 1)
>>  >>         +    return true;
>>  >>         +  return false;
>>  >>         +}
>>  >>         +
>>  >>
>>  >>
>>  >>     As I mentioned, I think it could be moved to os_linux.hpp
>> instead. Also, it
>>  >>     could be something like:
>>  >>
>>  >>     +bool os::Linux::isbound_to_single_node(void) {
>>  >>     +  struct bitmask* bmp;
>>  >>     +  unsigned long mask; // a mask element in the mask array
>>  >>     +  unsigned long max_num_masks;
>>  >>     +  int single_node = 0;
>>  >>     +
>>  >>     +  if (_numa_get_membind != NULL) {
>>  >>     +    bmp = _numa_get_membind();
>>  >>     +  } else {
>>  >>     +    return false;
>>  >>     +  }
>>  >>     +
>>  >>     +  max_num_masks = bmp->size / (8 * sizeof(unsigned long));
>>  >>     +
>>  >>     +  for (mask = 0; mask < max_num_masks; mask++) {
>>  >>     +    if (bmp->maskp[mask] != 0) { // at least one numa node in
>> the mask
>>  >>     +      if (bmp->maskp[mask] & (bmp->maskp[mask] - 1) == 0) {
>>  >>     +        single_node++; // a single numa node in the mask
>>  >>     +      } else {
>>  >>     +        return false;
>>  >>     +      }
>>  >>     +    }
>>  >>     +  }
>>  >>     +
>>  >>     +  if (single_node == 1) {
>>  >>     +    return true; // only a single mask with a single numa node
>>  >>     +  } else {
>>  >>     +    return false;
>>  >>     +  }
>>  >>     +}
>>  >>
>>  >>
>>  >>            bool os::get_page_info(char *start, page_info* info) {
>>  >>              return false;
>>  >>            }
>>  >>         @@ -2930,6 +2958,10 @@
>>  >>
>>  libnuma_dlsym(handle, "numa_bitmask_isbitset")));
>>  >>                  set_numa_distance(CAST_TO_FN_P
>> TR(numa_distance_func_t,
>>  >>
>>  libnuma_dlsym(handle, "numa_distance")));
>>  >>         +      set_numa_set_membind(CAST_TO_F
>> N_PTR(numa_set_membind_func_t,
>>  >>         +
>> libnuma_dlsym(handle, "numa_set_membind")));
>>  >>         +      set_numa_get_membind(CAST_TO_F
>> N_PTR(numa_get_membind_func_t,
>>  >>         +
>> libnuma_v2_dlsym(handle, "numa_get_membind")));
>>  >>                  if (numa_available() != -1) {
>>  >>                    set_numa_all_nodes((unsigned
>> long*)libnuma_dlsym(handle, "numa_all_nodes"));
>>  >>         @@ -3054,6 +3086,8 @@
>>  >>            os::Linux::numa_set_bind_policy_func_t
>> os::Linux::_numa_set_bind_policy;
>>  >>            os::Linux::numa_bitmask_isbitset_func_t
>> os::Linux::_numa_bitmask_isbitset;
>>  >>            os::Linux::numa_distance_func_t os::Linux::_numa_distance;
>>  >>         +os::Linux::numa_set_membind_func_t
>> os::Linux::_numa_set_membind;
>>  >>         +os::Linux::numa_get_membind_func_t
>> os::Linux::_numa_get_membind;
>>  >>            unsigned long* os::Linux::_numa_all_nodes;
>>  >>            struct bitmask* os::Linux::_numa_all_nodes_ptr;
>>  >>            struct bitmask* os::Linux::_numa_nodes_ptr;
>>  >>         @@ -4962,8 +4996,9 @@
>>  >>                if (!Linux::libnuma_init()) {
>>  >>                  UseNUMA = false;
>>  >>                } else {
>>  >>         -      if ((Linux::numa_max_node() < 1)) {
>>  >>         -        // There's only one node(they start from 0), disable
>> NUMA.
>>  >>         +      if ((Linux::numa_max_node() < 1) ||
>> Linux::issingle_node_bound()) {
>>  >>         +        // If there's only one node(they start from 0) or if
>> the process
>>  >>         +        // is bound explicitly to a single node using
>> membind, disable NUMA.
>>  >>                    UseNUMA = false;
>>  >>                  }
>>  >>                }
>>  >>         diff --git a/src/hotspot/os/linux/os_linux.hpp
>> b/src/hotspot/os/linux/os_linux.hpp
>>  >>         --- a/src/hotspot/os/linux/os_linux.hpp
>>  >>         +++ b/src/hotspot/os/linux/os_linux.hpp
>>  >>         @@ -228,6 +228,8 @@
>>  >>              typedef int (*numa_tonode_memory_func_t)(void *start,
>> size_t size, int node);
>>  >>              typedef void (*numa_interleave_memory_func_t)(void
>> *start, size_t size, unsigned long *nodemask);
>>  >>              typedef void (*numa_interleave_memory_v2_func_t)(void
>> *start, size_t size, struct bitmask* mask);
>>  >>         +  typedef void (*numa_set_membind_func_t)(struct bitmask
>> *mask);
>>  >>         +  typedef struct bitmask* (*numa_get_membind_func_t)(void);
>>  >>              typedef void (*numa_set_bind_policy_func_t)(int policy);
>>  >>              typedef int (*numa_bitmask_isbitset_func_t)(struct
>> bitmask *bmp, unsigned int n);
>>  >>         @@ -244,6 +246,8 @@
>>  >>              static numa_set_bind_policy_func_t _numa_set_bind_policy;
>>  >>              static numa_bitmask_isbitset_func_t
>> _numa_bitmask_isbitset;
>>  >>              static numa_distance_func_t _numa_distance;
>>  >>         +  static numa_set_membind_func_t _numa_set_membind;
>>  >>         +  static numa_get_membind_func_t _numa_get_membind;
>>  >>              static unsigned long* _numa_all_nodes;
>>  >>              static struct bitmask* _numa_all_nodes_ptr;
>>  >>              static struct bitmask* _numa_nodes_ptr;
>>  >>         @@ -259,6 +263,8 @@
>>  >>              static void set_numa_set_bind_policy(numa_set_bind_policy_func_t
>> func) { _numa_set_bind_policy = func; }
>>  >>              static void set_numa_bitmask_isbitset(numa_bitmask_isbitset_func_t
>> func) { _numa_bitmask_isbitset = func; }
>>  >>              static void set_numa_distance(numa_distance_func_t
>> func) { _numa_distance = func; }
>>  >>         +  static void set_numa_set_membind(numa_set_membind_func_t
>> func) { _numa_set_membind = func; }
>>  >>         +  static void set_numa_get_membind(numa_get_membind_func_t
>> func) { _numa_get_membind = func; }
>>  >>              static void set_numa_all_nodes(unsigned long* ptr) {
>> _numa_all_nodes = ptr; }
>>  >>              static void set_numa_all_nodes_ptr(struct bitmask **ptr)
>> { _numa_all_nodes_ptr = (ptr == NULL ? NULL : *ptr); }
>>  >>              static void set_numa_nodes_ptr(struct bitmask **ptr) {
>> _numa_nodes_ptr = (ptr == NULL ? NULL : *ptr); }
>>  >>         @@ -320,6 +326,15 @@
>>  >>                } else
>>  >>                  return 0;
>>  >>              }
>>  >>         +  // Check if node in bounded nodes
>>  >>
>>  >>
>>  >>     +  // Check if node is in bound node set. Maybe?
>>  >>
>>  >>
>>  >>         +  static bool isnode_in_bounded_nodes(int node) {
>>  >>         +    struct bitmask* bmp = _numa_get_membind != NULL ?
>> _numa_get_membind() : NULL;
>>  >>         +    if (bmp != NULL && _numa_bitmask_isbitset != NULL &&
>> _numa_bitmask_isbitset(bmp, node)) {
>>  >>         +      return true;
>>  >>         +    } else
>>  >>         +      return false;
>>  >>         +  }
>>  >>         +  static bool issingle_node_bound();
>>  >>
>>  >>
>>  >>     Looks like it can be re-written like:
>>  >>
>>  >>     +  static bool isnode_in_bound_nodes(int node) {
>>  >>     +    if (_numa_get_membind != NULL && _numa_bitmask_isbitset !=
>> NULL) {
>>  >>     +      return _numa_bitmask_isbitset(_numa_get_membind(), node);
>>  >>     +    } else {
>>  >>     +      return false;
>>  >>     +    }
>>  >>     +  }
>>  >>
>>  >>     ?
>>  >>
>>  >>
>>  >>            };
>>  >>            #endif // OS_LINUX_VM_OS_LINUX_HPP
>>  >>
>>  >>
>>  >>
>>  >
>>
>
>


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