Review Request: UseNUMAInterleaving #4

Deneau, Tom tom.deneau at amd.com
Tue Aug 23 12:17:33 PDT 2011


Igor --

For your comment on numa_get_leaf_groups, the bounds checking is done in NUMANodeListHolder::get_node_list_entry.  Although I wasn't sure what you were supposed
to return for indices that are out of bounds, so I returned -1.

I'll take care of the other cleanups.

-- Tom



> -----Original Message-----
> From: Igor Veresov [mailto:igor.veresov at oracle.com]
> Sent: Tuesday, August 23, 2011 1:53 PM
> To: Deneau, Tom
> Cc: hotspot-gc-dev at openjdk.java.net
> Subject: Re: Review Request: UseNUMAInterleaving #4
> 
>  Tom,
> 
> This looks good to me, except three minor things:
> 
> os_windows.cpp:
> 
> - 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.
> 
> 
> igor
> 
> 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
> > http://cr.openjdk.java.net/~tdeneau/UseNUMAInterleaving/webrev.04/
> >
> > 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
> 
> 



More information about the hotspot-gc-dev mailing list