Review Request: UseNUMAInterleaving #4

Igor Veresov igor.veresov at
Tue Aug 23 11:53:29 PDT 2011


This looks good to me, except three minor things:


- you should check for null here:
2630 ~NUMANodeListHolder() { 
> if (_numa_used_node_list != NULL) {
2631 FREE_C_HEAP_ARRAY(int, _numa_used_node_list);
> } 
2632 }

- if NUMANodeListHolder::build() will be called multiple times, you'll leak memory. I guess you should check if _numa_used_node_list is NULL and if not free it first.

- you didn't modify os::numa_get_leaf_groups() to handle the situation when the value of argument "size" is bigger than NUMANodeListHolder::get_count(). You can use MIN2 to adjust the value. See my comment in the previous mail.


On Tuesday, August 23, 2011 at 11:23 AM, Deneau, Tom wrote:

> Please review this patch which adds a new flag called
> UseNUMAInterleaving. This flag provides a subset of the functionality
> provided by UseNUMA. In Hotspot UseNUMA terminology,
> UseNUMAInterleaved makes all memory "numa_global" which is implemented
> as interleaved. This patch's main purpose is to provide that subset
> on OSes like Windows which do not support the full UseNUMA
> functionality. However, a simple implementation of UseNUMAInterleaving is
> also provided for other OSes
> The situations where this shows the biggest benefits would be:
>  * Windows platforms with multiple numa nodes (eg, 4)
>  * The JVM process is run across all the nodes (not affinitized to
>  one node).
>  * A workload that has enough threads so that it uses the majority
>  of the cores in the machine, so that the heap is being accessed
>  from many cores, including remote ones.
>  * Enough memory per node and a heap size such that the default heap
>  placement policy on windows would end up with the heap (or
>  nursery) placed on one node.
> jbb2005 and SPECPower_ssj2008 are examples of such workloads. In our
> measurements, we have seen some cases where the performance with
> UseNUMAInterleaving was 2.7x vs. the performance without. There were
> gains of varying sizes across all systems.
> The webrev is at
> Summary of changes in webrev.04 from webrev.03:
>  * As suggested by Igor Veresov, UseNUMA can imply
>  UseNUMAInterleaving on all platforms. This is in arguments.cpp
>  * In NUMANodeListHolder in os_windows.cpp, allocates the node_list
>  dynamically rather than assuming a length of 64. The method
>  NUMANodeListHolder::get_node_list_entry checks returns -1 for
>  indexes that are out of bounds. 
>  * Several code convention cleanups suggested by Igor.
>  * Merge with the new style system dll function resolutions from
>  "7016797: Hotspot: securely/restrictive load dlls and new API for
>  loading system dlls" Note: my new NUMA functions are outside the ifdefs.
> Summary of changes in webrev.03 from webrev.02:
>  * As suggested by Igor Veresov, reverts to using
>  UseNUMAInterleaving as the enabling flag. This will make it
>  easier in the future when there are GCs that enable fuller
>  UseNUMA on Windows.
>  * Adds a simple implementation of UseNUMAInterleaving on Linux and
>  Solaris, which just calls numa_make_global after commit_memory
>  and reserve_memory_special
>  * Adds a flag NUMAInterleaveGranularity which allows setting the
>  granularity with which we move to a different node in a memory
>  allocation. The default is 2MB. This flag only applies to
>  Windows for now.
>  * Several code cleanups in os_windows.cpp suggested by Igor.
> Summary of overall changes in os_windows.cpp:
>  * Some static routines were added to set things up init time. These
>  * check that the required APIs (VirtualAllocExNuma,
>  GetNumaHighestNodeNumber, GetNumaNodeProcessorMask) exist in
>  the OS
>  * build the list of numa nodes on which this process has affinity
>  * Changes to os::reserve_memory
>  * There was already a routine that reserved pages one page at a
>  time (used for Individual Large Page Allocation on WS2003).
>  This was abstracted to a separate routine, called
>  allocate_pages_individually. This gets called both for the
>  Individual Large Page Allocation thing mentioned above and for
>  UseNUMAInterleaving (for both small and large pages)
>  * When used for NUMA Interleaving this just goes thru the numa
>  node list in a round-robin fashion, allocating chunks at the
>  NUMAInterleaveGranularity using a different allocation for
>  each chunk
>  * Whether we do just a reserve or a combined reserve/commit is
>  determined by the caller of allocate_pages_individually
>  * When used with large pages, we do a Reserve and Commit at
>  the same time which is the way it always worked and the way
>  it has to work on windows.
>  * For small pages, only the reserve is done, the commit will
>  come later. (which is the way it worked for
>  non-interleaved)
>  * os::commit_memory changes
>  * If UseNUMAIntereaving is true, os::commit_memory has to check
>  whether it was being asked to commit memory that might have
>  come from multiple Reserve allocations, if so, the commits
>  must also be broken up. We don't keep any data structure to
>  keep track of this, we just use VirtualQuery which queries the
>  properties of a VA range and can tell us how much came from
>  one VirtualAlloc call.
> I do not have a bug id for this.
> -- Tom Deneau, AMD

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