[svn-r25033] Purpose:

    Merged r24993 from the trunk.
    Adds core VFD write tracking functionality. When enabled, the core VFD
    will track dirty regions of the file and only write out the changed
    regions. The new H5Pget/set_core_write_tracking() API call controls this
    feature. A new "core_paged" VFD target was added to the check-vfd target
    in test/Makefile.am that runs all tests with the new write tracking
    functionality.

Tested on:
    32-bit LE linux (jam)
    64-bit LE linux (koala)
    64-bit BE linux (ostrich)

    Each platform was tested with HDF5_DRIVER set to "core" and "core_paged".
    Jam was also tested with the standard sec2 driver.

9 files changed, 529 insertions, 90 deletions

diff --git a/release_docs/RELEASE.txt b/release_docs/RELEASE.txt
index 47de245..1187881 100644
--- a/release_docs/RELEASE.txt
+++ b/release_docs/RELEASE.txt
@@ -73,6 +73,16 @@ New Features
       than the application, such as when a debug memory manager is in use or
       when the HDF5 library is wrapped for use in a managed language like
       Python or Java. Fixes HDFFV-7710, 8519, and 8851. (DER - 2014/04/11)
+    - The core VFD can now be configured to track dirty regions in the file
+      and only write out the changed regions on flush/close. Additionally,
+      a "page aggregation" size can be set that will aggregate small writes
+      into larger writes. e.g., setting a 1 MiB page aggregation size will
+      logically partition the the in-memory file into 1 MiB pages that will be
+      written out in their entirety if even a single byte is dirtied. The
+      feature is controlled via the new H5Pset/get_core_write_tracking() API
+      call. A new "core_paged" target has been added to the check-vfd target
+      in test/Makefile.am that exercises the feature over all HDF5 VFD-aware
+      tests. (DER - 2014/04/12)
  
     Parallel Library
     ----------------
diff --git a/src/H5FDcore.c b/src/H5FDcore.c
index 7721f12..7c7dd39 100644
--- a/src/H5FDcore.c
+++ b/src/H5FDcore.c
@@ -25,19 +25,26 @@
 /* Interface initialization */
 #define H5_INTERFACE_INIT_FUNC  H5FD_core_init_interface
 
-
 #include "H5private.h"      /* Generic Functions            */
 #include "H5Eprivate.h"     /* Error handling               */
 #include "H5Fprivate.h"     /* File access                  */
 #include "H5FDprivate.h"    /* File drivers                 */
 #include "H5FDcore.h"       /* Core file driver             */
+#include "H5FLprivate.h"    /* Free lists                   */
 #include "H5Iprivate.h"     /* IDs                          */
 #include "H5MMprivate.h"    /* Memory management            */
 #include "H5Pprivate.h"     /* Property lists               */
+#include "H5SLprivate.h"    /* Skip lists                   */
 
 /* The driver identification number, initialized at runtime */
 static hid_t H5FD_CORE_g = 0;
 
+/* The skip list node type.  Represents a region in the file. */
+typedef struct H5FD_core_region_t {
+    haddr_t start;              /* Start address of the region          */
+    haddr_t end;                /* End address of the region            */
+} H5FD_core_region_t;
+
 /* The description of a file belonging to this driver. The 'eoa' and 'eof'
  * determine the amount of hdf5 address space in use and the high-water mark
  * of the file (the current size of the underlying memory).
@@ -50,6 +57,7 @@ typedef struct H5FD_core_t {
     haddr_t eof;                /* current allocated size               */
     size_t  increment;          /* multiples for mem allocation         */
     hbool_t backing_store;      /* write to file name on flush          */
+    size_t  bstore_page_size;   /* backing store page size              */
     int     fd;                 /* backing store file descriptor        */
     /* Information for determining uniqueness of a file with a backing store */
 #ifndef H5_HAVE_WIN32_API
@@ -85,6 +93,7 @@ typedef struct H5FD_core_t {
 #endif /* H5_HAVE_WIN32_API */
     hbool_t dirty;                              /* changes not saved?       */
     H5FD_file_image_callbacks_t fi_callbacks;   /* file image callbacks     */
+    H5SL_t *dirty_list;                         /* dirty parts of the file  */
 } H5FD_core_t;
 
 /* Driver-specific file access properties */
@@ -117,6 +126,9 @@ typedef struct H5FD_core_fapl_t {
                                 (size_t)((A)+(Z))<(size_t)(A))
 
 /* Prototypes */
+static herr_t H5FD_core_add_dirty_region(H5FD_core_t *file, haddr_t start, haddr_t end);
+static herr_t H5FD_core_destroy_dirty_list(H5FD_core_t *file);
+static herr_t H5FD_core_write_to_bstore(H5FD_core_t *file, haddr_t addr, size_t size);
 static void *H5FD_core_fapl_get(H5FD_t *_file);
 static H5FD_t *H5FD_core_open(const char *name, unsigned flags, hid_t fapl_id,
             haddr_t maxaddr);
@@ -168,6 +180,251 @@ static const H5FD_class_t H5FD_core_g = {
     H5FD_FLMAP_DICHOTOMY        /* fl_map               */
 };
 
+/* Define a free list to manage the region type */
+H5FL_DEFINE(H5FD_core_region_t);
+
+
+/*-------------------------------------------------------------------------
+ * Function:    H5FD_core_add_dirty_region
+ *
+ * Purpose:     Add a new dirty region to the list for later flushing
+ *              to the backing store.
+ *
+ * Return:      SUCCEED/FAIL
+ *
+ *-------------------------------------------------------------------------
+ */
+static herr_t
+H5FD_core_add_dirty_region(H5FD_core_t *file, haddr_t start, haddr_t end)
+{
+    H5FD_core_region_t *b_item  = NULL;
+    H5FD_core_region_t *a_item  = NULL;
+    H5FD_core_region_t *item    = NULL;
+    haddr_t     b_addr          = 0;
+    haddr_t     a_addr          = 0;
+    hbool_t     create_new_node = TRUE;
+    herr_t      ret_value       = SUCCEED;
+#ifdef DER
+    hbool_t     was_adjusted    = FALSE;
+#endif
+
+    FUNC_ENTER_NOAPI_NOINIT
+
+    HDassert(file);
+    HDassert(file->dirty_list);
+    HDassert(start <= end);
+
+#ifdef DER
+fprintf(stderr, "Add region: (%llu, %llu)\n", start, end);
+#endif
+
+    /* Adjust the dirty region to the nearest block boundaries */
+    if(start % file->bstore_page_size != 0) {
+        start = (start / file->bstore_page_size) * file->bstore_page_size;
+#ifdef DER
+        was_adjusted = TRUE;
+#endif
+    }
+    if(end % file->bstore_page_size != (file->bstore_page_size - 1)) {
+        end = (((end / file->bstore_page_size) + 1) * file->bstore_page_size) - 1;
+        if(end > file->eof){
+#ifdef DER
+fprintf(stderr, "Adjusted to EOF\n");
+#endif
+            end = file->eof - 1;
+        }
+#ifdef DER
+        was_adjusted = TRUE;
+#endif
+    }
+
+#ifdef DER
+if(was_adjusted)
+    fprintf(stderr, "Adjusted region: (%llu, %llu)\n", start, end);
+#endif
+
+    /* Get the regions before and after the intended insertion point */
+    b_addr = start +1;
+    a_addr = end + 2;
+    b_item = (H5FD_core_region_t *)H5SL_less(file->dirty_list, &b_addr);
+    a_item = (H5FD_core_region_t *)H5SL_less(file->dirty_list, &a_addr);
+
+    /* Check to see if we need to extend the upper end of the NEW region */
+    if(a_item) {
+        if(start < a_item->start && end < a_item->end) {
+
+            /* Extend the end of the NEW region to match the existing AFTER region */
+            end = a_item->end;
+        }
+    }
+    /* Attempt to extend the PREV region */
+    if(b_item) {
+        if(start <= b_item->end + 1) {
+
+            /* Need to set this for the delete algorithm */
+            start = b_item->start;
+
+            /* We won't need to insert a new node since we can
+             * just update an existing one instead.
+             */
+            create_new_node = FALSE;
+        }
+    }
+
+    /* Remove any old nodes that are no longer needed */
+    while(a_item && a_item->start > start) {
+
+        H5FD_core_region_t *less;
+        haddr_t key = a_item->start - 1;
+
+        /* Save the previous node before we trash this one */
+        less = (H5FD_core_region_t *)H5SL_less(file->dirty_list, &key);
+
+        /* Delete this node */
+        a_item = (H5FD_core_region_t *)H5SL_remove(file->dirty_list, &a_item->start);
+        a_item = H5FL_FREE(H5FD_core_region_t, a_item);
+
+        /* Set up to check the next node */
+        if(less)
+            a_item = less;
+    }
+
+    /* Insert the new node */
+    if(create_new_node) {
+        if(NULL == (item = (H5FD_core_region_t *)H5SL_search(file->dirty_list, &start))) {
+            /* Ok to insert.  No pre-existing node with that key. */
+            item = (H5FD_core_region_t *)H5FL_CALLOC(H5FD_core_region_t);
+            item->start = start;
+            item->end = end;
+            if(H5SL_insert(file->dirty_list, item, &item->start) < 0)
+                HGOTO_ERROR(H5E_SLIST, H5E_CANTINSERT, FAIL, "can't insert new dirty region: (%llu, %llu)\n", start, end)
+        }
+        else {
+            /* Store the new item endpoint if it's bigger */
+            item->end = (item->end < end) ? end : item->end;
+        }
+    }
+    else {
+        /* Update the size of the before region */
+        if(b_item->end < end)
+            b_item->end = end;
+    }
+
+done:
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* end H5FD_core_add_dirty_region() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:    H5FD_core_destroy_dirty_list
+ *
+ * Purpose:     Completely destroy the dirty list.
+ *
+ * Return:      SUCCEED/FAIL
+ *
+ *-------------------------------------------------------------------------
+ */
+static herr_t
+H5FD_core_destroy_dirty_list(H5FD_core_t *file)
+{
+    herr_t ret_value = SUCCEED;
+
+    FUNC_ENTER_NOAPI_NOINIT
+
+    HDassert(file);
+
+    /* Destroy the list, including any remaining list elements */
+    if(file->dirty_list) {
+        H5FD_core_region_t *region = NULL;
+
+#ifdef DER
+{
+size_t count = H5SL_count(file->dirty_list);
+if(count != 0)
+    fprintf(stderr, "LIST NOT EMPTY AT DESTROY\n");
+}
+#endif
+        while(NULL != (region = (H5FD_core_region_t *)H5SL_remove_first(file->dirty_list)))
+            region = H5FL_FREE(H5FD_core_region_t, region);
+
+        if(H5SL_close(file->dirty_list) < 0)
+            HGOTO_ERROR(H5E_SLIST, H5E_CLOSEERROR, FAIL, "can't close core vfd dirty list")
+        file->dirty_list = NULL;
+    }
+
+done:
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* end H5FD_core_destroy_dirty_list() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:    H5FD_core_write_to_bstore
+ *
+ * Purpose:     Write data to the backing store.
+ *
+ * Return:      SUCCEED/FAIL
+ *
+ *-------------------------------------------------------------------------
+ */
+static herr_t H5FD_core_write_to_bstore(H5FD_core_t *file, haddr_t addr, size_t size)
+{
+    unsigned char  *ptr         = file->mem + addr;     /* mutable pointer into the
+                                                         * buffer (can't change mem)
+                                                         */
+    herr_t          ret_value   = SUCCEED;              /* Return value */
+
+    FUNC_ENTER_NOAPI_NOINIT
+
+    HDassert(file);
+
+    /* Write to backing store */
+    if((off_t)addr != HDlseek(file->fd, (off_t)addr, SEEK_SET))
+        HGOTO_ERROR(H5E_IO, H5E_SEEKERROR, FAIL, "error seeking in backing store")
+
+    while (size > 0) {
+
+        h5_posix_io_t       bytes_in        = 0;    /* # of bytes to write  */
+        h5_posix_io_ret_t   bytes_wrote     = -1;   /* # of bytes written   */
+
+        /* Trying to write more bytes than the return type can handle is
+         * undefined behavior in POSIX.
+         */
+        if(size > H5_POSIX_MAX_IO_BYTES)
+            bytes_in = H5_POSIX_MAX_IO_BYTES;
+        else
+            bytes_in = (h5_posix_io_t)size;
+
+#ifdef DER
+fprintf(stderr, "\nNEW\n");
+#endif
+        do {
+            bytes_wrote = HDwrite(file->fd, ptr, bytes_in);
+#ifdef DER
+fprintf(stderr, "bytes wrote: %lu\n", bytes_wrote);
+#endif
+        } while(-1 == bytes_wrote && EINTR == errno);
+
+        if(-1 == bytes_wrote) { /* error */
+            int myerrno = errno;
+            time_t mytime = HDtime(NULL);
+            HDoff_t myoffset = HDlseek(file->fd, (HDoff_t)0, SEEK_CUR);
+
+            HGOTO_ERROR(H5E_IO, H5E_WRITEERROR, FAIL, "write to backing store failed: time = %s, filename = '%s', file descriptor = %d, errno = %d, error message = '%s', ptr = %p, total write size = %llu, bytes this sub-write = %llu, bytes actually written = %llu, offset = %llu", HDctime(&mytime), file->name, file->fd, myerrno, HDstrerror(myerrno), ptr, (unsigned long long)size, (unsigned long long)bytes_in, (unsigned long long)bytes_wrote, (unsigned long long)myoffset);
+        } /* end if */
+
+        HDassert(bytes_wrote > 0);
+        HDassert((size_t)bytes_wrote <= size);
+
+        size -= (size_t)bytes_wrote;
+        ptr = (unsigned char *)ptr + bytes_wrote;
+
+    } /* end while */
+
+done:
+    FUNC_LEAVE_NOAPI(ret_value)
+
+} /* end H5FD_core_write_to_bstore() */
+
 
 /*-------------------------------------------------------------------------
  * Function:    H5FD_core_init_interface
@@ -564,6 +821,40 @@ H5FD_core_open(const char *name, unsigned flags, hid_t fapl_id, haddr_t maxaddr)
         } /* end if */
     } /* end if */
 
+    /* Set up write tracking if the backing store is on */
+    file->dirty_list = NULL;
+    if(fa->backing_store) {
+        hbool_t write_tracking_flag = FALSE;    /* what the user asked for */
+        hbool_t use_write_tracking = FALSE;     /* what we're actually doing */
+
+        /* Get the write tracking flag */
+        if(H5P_get(plist, H5F_ACS_CORE_WRITE_TRACKING_FLAG_NAME, &write_tracking_flag) < 0)
+            HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, NULL, "can't get core VFD write tracking flag");
+
+        /* Get the page size */
+        if(H5P_get(plist, H5F_ACS_CORE_WRITE_TRACKING_PAGE_SIZE_NAME, &(file->bstore_page_size)) < 0)
+            HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, NULL, "can't get core VFD write tracking page size");
+
+        /* default is to have write tracking OFF for create (hence the check to see
+         * if the user explicitly set a page size) and ON with the default page size
+         * on open (when not read-only).
+         */
+        /* Only use write tracking if the file is open for writing */
+        use_write_tracking = 
+            TRUE == write_tracking_flag         /* user asked for write tracking */
+            && !(o_flags & O_RDONLY)            /* file is open for writing (i.e. not read-only) */
+            && file->bstore_page_size != 0;     /* page size is not zero */
+
+        /* initialize the dirty list */
+        if(use_write_tracking) {
+            if(NULL == (file->dirty_list = H5SL_create(H5SL_TYPE_HADDR, NULL)))
+                HGOTO_ERROR(H5E_SLIST, H5E_CANTCREATE, NULL, "can't create core vfd dirty region list");
+#ifdef DER
+fprintf(stderr, "\n");
+#endif
+        } /* end if */
+    } /* end if */
+
     /* Set return value */
     ret_value = (H5FD_t *)file;
 
@@ -602,7 +893,12 @@ H5FD_core_close(H5FD_t *_file)
 
     /* Flush any changed buffers */
     if(H5FD_core_flush(_file, (hid_t)-1, TRUE) < 0)
-        HGOTO_ERROR(H5E_FILE, H5E_CANTFLUSH, FAIL, "unable to flush file")
+        HGOTO_ERROR(H5E_FILE, H5E_CANTFLUSH, FAIL, "unable to flush core vfd backing store")
+
+    /* Destroy the dirty region list */
+    if(file->dirty_list)
+        if(H5FD_core_destroy_dirty_list(file) != SUCCEED)
+            HGOTO_ERROR(H5E_VFL, H5E_CANTFREE, FAIL, "unable to free core vfd dirty region list")
 
     /* Release resources */
     if(file->fd >= 0)
@@ -1023,6 +1319,14 @@ H5FD_core_write(H5FD_t *_file, H5FD_mem_t UNUSED type, hid_t UNUSED dxpl_id, had
         file->eof = new_eof;
     } /* end if */
 
+    /* Add the buffer region to the dirty list if using that optimization */
+    if(file->dirty_list) {
+        haddr_t start = addr;
+        haddr_t end = addr + (haddr_t)size - 1;
+        if(H5FD_core_add_dirty_region(file, start, end) != SUCCEED)
+            HGOTO_ERROR(H5E_VFL, H5E_CANTINSERT, FAIL, "unable to add core VFD dirty region during write call - addresses: start=%llu end=%llu", start, end)
+    }
+
     /* Write from BUF to memory */
     HDmemcpy(file->mem + addr, buf, size);
 
@@ -1057,45 +1361,50 @@ H5FD_core_flush(H5FD_t *_file, hid_t UNUSED dxpl_id, unsigned UNUSED closing)
 
     /* Write to backing store */
     if (file->dirty && file->fd >= 0 && file->backing_store) {
-        haddr_t size = file->eof;
-        unsigned char *ptr = file->mem;
 
-        if(0 != HDlseek(file->fd, (off_t)0, SEEK_SET))
-            HGOTO_ERROR(H5E_IO, H5E_SEEKERROR, FAIL, "error seeking in backing store")
-        
-        while (size > 0) {
+        /* Use the dirty list, if available */
+        if(file->dirty_list) {
+            H5FD_core_region_t *item = NULL;
+            size_t size;
 
-            h5_posix_io_t       bytes_in        = 0;    /* # of bytes to write  */
-            h5_posix_io_ret_t   bytes_wrote     = -1;   /* # of bytes written   */ 
+#ifdef DER
+    fprintf(stderr, "FLUSHING. DIRTY LIST:\n");
+#endif
+            while(NULL != (item = (H5FD_core_region_t *)H5SL_remove_first(file->dirty_list))) {
 
-            /* Trying to write more bytes than the return type can handle is
-             * undefined behavior in POSIX.
-             */
-            if(size > H5_POSIX_MAX_IO_BYTES)
-                bytes_in = H5_POSIX_MAX_IO_BYTES;
-            else
-                bytes_in = (h5_posix_io_t)size;
-
-            do {
-                bytes_wrote = HDwrite(file->fd, ptr, bytes_in);
-            } while(-1 == bytes_wrote && EINTR == errno);
-            
-            if(-1 == bytes_wrote) { /* error */
-                int myerrno = errno;
-                time_t mytime = HDtime(NULL);
-                HDoff_t myoffset = HDlseek(file->fd, (HDoff_t)0, SEEK_CUR);
-
-                HGOTO_ERROR(H5E_IO, H5E_WRITEERROR, FAIL, "write to backing store failed: time = %s, filename = '%s', file descriptor = %d, errno = %d, error message = '%s', ptr = %p, total write size = %llu, bytes this sub-write = %llu, bytes actually written = %llu, offset = %llu", HDctime(&mytime), file->name, file->fd, myerrno, HDstrerror(myerrno), ptr, (unsigned long long)size, (unsigned long long)bytes_in, (unsigned long long)bytes_wrote, (unsigned long long)myoffset);
-            } /* end if */
-            
-            HDassert(bytes_wrote > 0);
-            HDassert((size_t)bytes_wrote <= size);
+                /* The file may have been truncated, so check for that
+                 * and skip or adjust as necessary.
+                 */
+                if(item->start < file->eof) {
+                    if(item->end >= file->eof)
+                        item->end = file->eof - 1;
+                    size = (size_t)((item->end - item->start) + 1);
+#ifdef DER
+fprintf(stderr, "(%llu, %llu : %lu)\n", item->start, item->end, size);
+#endif
+                    if(H5FD_core_write_to_bstore(file, item->start, size) != SUCCEED)
+                        HGOTO_ERROR(H5E_VFL, H5E_WRITEERROR, FAIL, "unable to write to backing store")
+                } /* end if */
+                
+                item = H5FL_FREE(H5FD_core_region_t, item);
+            } /* end while */
+
+ 
+#ifdef DER
+fprintf(stderr, "EOF: %llu\n", file->eof);
+fprintf(stderr, "EOA: %llu\n", file->eoa);
+if(file->eoa > file->eof)
+    fprintf(stderr, "*** EOA BADNESS ***\n");
+fprintf(stderr, "\n");
+#endif
+        }
+        /* Otherwise, write the entire file out at once */
+        else {
+            if(H5FD_core_write_to_bstore(file, (haddr_t)0, (size_t)file->eof) != SUCCEED)
+                HGOTO_ERROR(H5E_VFL, H5E_WRITEERROR, FAIL, "unable to write to backing store")
 
-            size -= (size_t)bytes_wrote;
-            ptr = (unsigned char *)ptr + bytes_wrote;
-            
         } /* end while */
-        
+
         file->dirty = FALSE;
     }
 
@@ -1215,10 +1524,14 @@ H5FD_core_truncate(H5FD_t *_file, hid_t UNUSED dxpl_id, hbool_t closing)
                  * re-extended later.  This may happen on Open VMS. */
                 if(-1 == HDlseek(file->fd, (HDoff_t)0, SEEK_SET))
                     HSYS_GOTO_ERROR(H5E_IO, H5E_SEEKERROR, FAIL, "unable to seek to proper position")
-#endif
+#endif /* H5_VMS */
                 if(-1 == HDftruncate(file->fd, (HDoff_t)new_eof))
                     HSYS_GOTO_ERROR(H5E_IO, H5E_SEEKERROR, FAIL, "unable to extend file properly")
 #endif /* H5_HAVE_WIN32_API */
+
+#ifdef DER
+fprintf(stderr, "OLD: Truncated to: %llu\n", file->eoa);
+#endif
             } /* end if */
 
             /* Update the eof value */
@@ -1229,3 +1542,4 @@ H5FD_core_truncate(H5FD_t *_file, hid_t UNUSED dxpl_id, hbool_t closing)
 done:
     FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5FD_core_truncate() */
+
diff --git a/src/H5Fprivate.h b/src/H5Fprivate.h
index 1a21ac3..4d6e5ba 100644
--- a/src/H5Fprivate.h
+++ b/src/H5Fprivate.h
@@ -402,6 +402,8 @@ typedef struct H5F_blk_aggr_t H5F_blk_aggr_t;
 #define H5F_ACS_WANT_POSIX_FD_NAME              "want_posix_fd" /* Internal: query the file descriptor from the core VFD, instead of the memory address */
 #define H5F_ACS_EFC_SIZE_NAME                   "efc_size"      /* Size of external file cache */
 #define H5F_ACS_FILE_IMAGE_INFO_NAME            "file_image_info" /* struct containing initial file image and callback info */
+#define H5F_ACS_CORE_WRITE_TRACKING_FLAG_NAME       "core_write_tracking_flag" /* Whether or not core VFD backing store write tracking is enabled */
+#define H5F_ACS_CORE_WRITE_TRACKING_PAGE_SIZE_NAME  "core_write_tracking_page_size" /* The page size in kiB when core VFD write tracking is enabled */
 
 /* ======================== File Mount properties ====================*/
 #define H5F_MNT_SYM_LOCAL_NAME 		"local"                 /* Whether absolute symlinks local to file. */
diff --git a/src/H5Pfapl.c b/src/H5Pfapl.c
index ad717e7..ee483cd 100644
--- a/src/H5Pfapl.c
+++ b/src/H5Pfapl.c
@@ -129,7 +129,12 @@
 #define H5F_ACS_FILE_IMAGE_INFO_DEL             H5P_file_image_info_del
 #define H5F_ACS_FILE_IMAGE_INFO_COPY            H5P_file_image_info_copy
 #define H5F_ACS_FILE_IMAGE_INFO_CLOSE           H5P_file_image_info_close
-
+/* Definition of core VFD write tracking flag */
+#define H5F_ACS_CORE_WRITE_TRACKING_FLAG_SIZE   sizeof(hbool_t)
+#define H5F_ACS_CORE_WRITE_TRACKING_FLAG_DEF    FALSE
+/* Definition of core VFD write tracking page size */
+#define H5F_ACS_CORE_WRITE_TRACKING_PAGE_SIZE_SIZE      sizeof(size_t)
+#define H5F_ACS_CORE_WRITE_TRACKING_PAGE_SIZE_DEF       524288
 
 /******************/
 /* Local Typedefs */
@@ -186,7 +191,6 @@ const H5P_libclass_t H5P_CLS_FACC[1] = {{
 /* Local Variables */
 /*******************/
 
-
 
 /*-------------------------------------------------------------------------
  * Function:    H5P_facc_reg_prop
@@ -223,6 +227,8 @@ H5P_facc_reg_prop(H5P_genclass_t *pclass)
     hbool_t want_posix_fd = H5F_ACS_WANT_POSIX_FD_DEF;          /* Default setting for retrieving 'handle' from core VFD */
     unsigned efc_size = H5F_ACS_EFC_SIZE_DEF;                   /* Default external file cache size */
     H5FD_file_image_info_t file_image_info = H5F_ACS_FILE_IMAGE_INFO_DEF;  /* Default file image info and callbacks */
+    hbool_t core_write_tracking_flag = H5F_ACS_CORE_WRITE_TRACKING_FLAG_DEF;              /* Default setting for core VFD write tracking */
+    size_t core_write_tracking_page_size = H5F_ACS_CORE_WRITE_TRACKING_PAGE_SIZE_DEF;     /* Default core VFD write tracking page size */
     herr_t ret_value = SUCCEED;         /* Return value */
 
     FUNC_ENTER_NOAPI_NOINIT
@@ -312,6 +318,16 @@ H5P_facc_reg_prop(H5P_genclass_t *pclass)
     if(H5P_register_real(pclass, H5F_ACS_FILE_IMAGE_INFO_NAME, H5F_ACS_FILE_IMAGE_INFO_SIZE, &file_image_info, NULL, NULL, NULL, H5F_ACS_FILE_IMAGE_INFO_DEL, H5F_ACS_FILE_IMAGE_INFO_COPY, NULL, H5F_ACS_FILE_IMAGE_INFO_CLOSE) < 0)
         HGOTO_ERROR(H5E_PLIST, H5E_CANTINSERT, FAIL, "can't insert property into class")
 
+    /* Register the core VFD backing store write tracking flag */
+    if(H5P_register_real(pclass, H5F_ACS_CORE_WRITE_TRACKING_FLAG_NAME, H5F_ACS_CORE_WRITE_TRACKING_FLAG_SIZE, &core_write_tracking_flag, 
+            NULL, NULL, NULL, NULL, NULL, NULL, NULL) < 0)
+        HGOTO_ERROR(H5E_PLIST, H5E_CANTINSERT, FAIL, "can't insert property into class")
+
+    /* Register the size of the core VFD backing store page size */
+    if(H5P_register_real(pclass, H5F_ACS_CORE_WRITE_TRACKING_PAGE_SIZE_NAME, H5F_ACS_CORE_WRITE_TRACKING_PAGE_SIZE_SIZE, &core_write_tracking_page_size, 
+            NULL, NULL, NULL, NULL, NULL, NULL, NULL) < 0)
+        HGOTO_ERROR(H5E_PLIST, H5E_CANTINSERT, FAIL, "can't insert property into class")
+
 done:
     FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5P_facc_reg_prop() */
@@ -2347,3 +2363,76 @@ done:
     FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5P_file_image_info_close() */
 
+
+/*-------------------------------------------------------------------------
+ * Function:	H5Pset_core_write_tracking
+ *
+ * Purpose:	Enables/disables core VFD write tracking and page
+ *              aggregation size.
+ *
+ * Return:	Non-negative on success/Negative on failure
+ *
+ *-------------------------------------------------------------------------
+ */
+herr_t
+H5Pset_core_write_tracking(hid_t plist_id, hbool_t is_enabled, size_t page_size)
+{
+    H5P_genplist_t *plist;        /* Property list pointer */
+    herr_t ret_value = SUCCEED;   /* return value */
+
+    FUNC_ENTER_API(FAIL)
+    H5TRACE3("e", "ibz", plist_id, is_enabled, page_size);
+
+    /* Get the plist structure */
+    if(NULL == (plist = H5P_object_verify(plist_id, H5P_FILE_ACCESS)))
+        HGOTO_ERROR(H5E_ATOM, H5E_BADATOM, FAIL, "can't find object for ID")
+
+    /* Set values */
+    if(H5P_set(plist, H5F_ACS_CORE_WRITE_TRACKING_FLAG_NAME, &is_enabled) < 0)
+        HGOTO_ERROR(H5E_PLIST, H5E_CANTSET, FAIL, "can't set core VFD write tracking flag")
+    if(H5P_set(plist, H5F_ACS_CORE_WRITE_TRACKING_PAGE_SIZE_NAME, &page_size) < 0)
+        HGOTO_ERROR(H5E_PLIST, H5E_CANTSET, FAIL, "can't set core VFD write tracking page size")
+
+done:
+    FUNC_LEAVE_API(ret_value)
+}
+
+
+/*-------------------------------------------------------------------------
+ * Function:	H5Pget_core_write_tracking
+ *
+ * Purpose:	Gets information about core VFD write tracking and page
+ *              aggregation size.
+ *
+ * Return:	Non-negative on success/Negative on failure
+ *
+ *-------------------------------------------------------------------------
+ */
+herr_t
+H5Pget_core_write_tracking(hid_t plist_id, hbool_t *is_enabled, size_t *page_size)
+{
+    H5P_genplist_t *plist;      /* Property list pointer */
+    herr_t ret_value = SUCCEED;   /* return value */
+
+    FUNC_ENTER_API(FAIL)
+    H5TRACE3("e", "i*b*z", plist_id, is_enabled, page_size);
+
+    /* Get the plist structure */
+    if(NULL == (plist = H5P_object_verify(plist_id, H5P_FILE_ACCESS)))
+        HGOTO_ERROR(H5E_ATOM, H5E_BADATOM, FAIL, "can't find object for ID")
+
+    /* Get values */
+    if(is_enabled) {
+        if(H5P_get(plist, H5F_ACS_CORE_WRITE_TRACKING_FLAG_NAME, is_enabled) < 0)
+            HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "can't get core VFD write tracking flag")
+    } /* end if */
+
+    if(page_size) {
+        if(H5P_get(plist, H5F_ACS_CORE_WRITE_TRACKING_PAGE_SIZE_NAME, page_size) < 0)
+            HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "can't get core VFD write tracking page size")
+    } /* end if */
+
+done:
+    FUNC_LEAVE_API(ret_value)
+}
+
diff --git a/src/H5Ppublic.h b/src/H5Ppublic.h
index 10fa782..1d8ced4 100644
--- a/src/H5Ppublic.h
+++ b/src/H5Ppublic.h
@@ -293,7 +293,6 @@ H5_DLL herr_t H5Pget_shared_mesg_index(hid_t plist_id, unsigned index_num, unsig
 H5_DLL herr_t H5Pset_shared_mesg_phase_change(hid_t plist_id, unsigned max_list, unsigned min_btree);
 H5_DLL herr_t H5Pget_shared_mesg_phase_change(hid_t plist_id, unsigned *max_list, unsigned *min_btree);
 
-
 /* File access property list (FAPL) routines */
 H5_DLL herr_t H5Pset_alignment(hid_t fapl_id, hsize_t threshold,
     hsize_t alignment);
@@ -341,6 +340,9 @@ H5_DLL herr_t H5Pset_file_image_callbacks(hid_t fapl_id,
 H5_DLL herr_t H5Pget_file_image_callbacks(hid_t fapl_id,
        H5FD_file_image_callbacks_t *callbacks_ptr);
 
+H5_DLL herr_t H5Pset_core_write_tracking(hid_t fapl_id, hbool_t is_enabled, size_t page_size);
+H5_DLL herr_t H5Pget_core_write_tracking(hid_t fapl_id, hbool_t *is_enabled, size_t *page_size);
+
 /* Dataset creation property list (DCPL) routines */
 H5_DLL herr_t H5Pset_layout(hid_t plist_id, H5D_layout_t layout);
 H5_DLL H5D_layout_t H5Pget_layout(hid_t plist_id);
diff --git a/test/Makefile.am b/test/Makefile.am
index 18bb88d..08b8b4f 100644
--- a/test/Makefile.am
+++ b/test/Makefile.am
@@ -103,7 +103,7 @@ LDADD=libh5test.la $(LIBHDF5)
 ttsafe_SOURCES=ttsafe.c ttsafe_dcreate.c ttsafe_error.c ttsafe_cancel.c       \
                ttsafe_acreate.c
 
-VFD_LIST = sec2 stdio core split multi family
+VFD_LIST = sec2 stdio core core_paged split multi family
 if DIRECT_VFD_CONDITIONAL
   VFD_LIST += direct
 endif
diff --git a/test/Makefile.in b/test/Makefile.in
index 4850cf7..9b435de 100644
--- a/test/Makefile.in
+++ b/test/Makefile.in
@@ -1119,7 +1119,8 @@ LDADD = libh5test.la $(LIBHDF5)
 ttsafe_SOURCES = ttsafe.c ttsafe_dcreate.c ttsafe_error.c ttsafe_cancel.c       \
                ttsafe_acreate.c
 
-VFD_LIST = sec2 stdio core split multi family $(am__append_4)
+VFD_LIST = sec2 stdio core core_paged split multi family \
+	$(am__append_4)
 
 # Sources for testhdf5 executable
 testhdf5_SOURCES = testhdf5.c tarray.c tattr.c tchecksum.c tconfig.c tfile.c \
diff --git a/test/h5test.c b/test/h5test.c
index d3fdc8d..2afda36 100644
--- a/test/h5test.c
+++ b/test/h5test.c
@@ -511,64 +511,71 @@ h5_fileaccess(void)
     /* First use the environment variable, then the constant */
     val = HDgetenv("HDF5_DRIVER");
 #ifdef HDF5_DRIVER
-    if (!val) val = HDF5_DRIVER;
+    if (!val)
+        val = HDF5_DRIVER;
 #endif
 
-    if ((fapl=H5Pcreate(H5P_FILE_ACCESS))<0) return -1;
-    if (!val || !*val) return fapl; /*use default*/
+    if ((fapl=H5Pcreate(H5P_FILE_ACCESS))<0)
+        return -1;
+    if (!val || !*val)
+        return fapl; /*use default*/
 
     HDstrncpy(s, val, sizeof s);
     s[sizeof(s)-1] = '\0';
     if (NULL==(name=HDstrtok(s, " \t\n\r"))) return fapl;
 
     if (!HDstrcmp(name, "sec2")) {
-  /* Unix read() and write() system calls */
-  if (H5Pset_fapl_sec2(fapl)<0) return -1;
+        /* Unix read() and write() system calls */
+        if (H5Pset_fapl_sec2(fapl)<0) return -1;
     } else if (!HDstrcmp(name, "stdio")) {
-  /* Standard C fread() and fwrite() system calls */
-  if (H5Pset_fapl_stdio(fapl)<0) return -1;
+        /* Standard C fread() and fwrite() system calls */
+        if (H5Pset_fapl_stdio(fapl)<0) return -1;
     } else if (!HDstrcmp(name, "core")) {
-  /* In-core temporary file with 1MB increment */
-  if (H5Pset_fapl_core(fapl, (size_t)1, TRUE)<0) return -1;
-    } else if (!HDstrcmp(name, "split")) {
-  /* Split meta data and raw data each using default driver */
-  if (H5Pset_fapl_split(fapl,
+        /* In-memory driver settings (backing store on, 1 MB increment) */
+        if (H5Pset_fapl_core(fapl, (size_t)1, TRUE)<0) return -1;
+    } else if (!HDstrcmp(name, "core_paged")) {
+        /* In-memory driver with write tracking and paging on */
+        if (H5Pset_fapl_core(fapl, (size_t)1, TRUE)<0) return -1;
+        if (H5Pset_core_write_tracking(fapl, TRUE, (size_t)524288)<0) return -1;
+     } else if (!HDstrcmp(name, "split")) {
+        /* Split meta data and raw data each using default driver */
+        if (H5Pset_fapl_split(fapl,
             "-m.h5", H5P_DEFAULT,
             "-r.h5", H5P_DEFAULT)<0)
-      return -1;
+            return -1;
     } else if (!HDstrcmp(name, "multi")) {
-  /* Multi-file driver, general case of the split driver */
-  H5FD_mem_t memb_map[H5FD_MEM_NTYPES];
-  hid_t memb_fapl[H5FD_MEM_NTYPES];
-  const char *memb_name[H5FD_MEM_NTYPES];
-  char sv[H5FD_MEM_NTYPES][1024];
-  haddr_t memb_addr[H5FD_MEM_NTYPES];
+        /* Multi-file driver, general case of the split driver */
+        H5FD_mem_t memb_map[H5FD_MEM_NTYPES];
+        hid_t memb_fapl[H5FD_MEM_NTYPES];
+        const char *memb_name[H5FD_MEM_NTYPES];
+        char sv[H5FD_MEM_NTYPES][1024];
+        haddr_t memb_addr[H5FD_MEM_NTYPES];
         H5FD_mem_t  mt;
 
-  HDmemset(memb_map, 0, sizeof memb_map);
-  HDmemset(memb_fapl, 0, sizeof memb_fapl);
-  HDmemset(memb_name, 0, sizeof memb_name);
-  HDmemset(memb_addr, 0, sizeof memb_addr);
-
-  HDassert(HDstrlen(multi_letters)==H5FD_MEM_NTYPES);
-  for(mt = H5FD_MEM_DEFAULT; mt < H5FD_MEM_NTYPES; H5_INC_ENUM(H5FD_mem_t, mt)) {
-      memb_fapl[mt] = H5P_DEFAULT;
-      sprintf(sv[mt], "%%s-%c.h5", multi_letters[mt]);
-      memb_name[mt] = sv[mt];
-      memb_addr[mt] = (haddr_t)MAX(mt - 1, 0) * (HADDR_MAX / 10);
-  } /* end for */
-
-  if (H5Pset_fapl_multi(fapl, memb_map, memb_fapl, memb_name,
-            memb_addr, FALSE)<0) {
-      return -1;
-  }
+        HDmemset(memb_map, 0, sizeof memb_map);
+        HDmemset(memb_fapl, 0, sizeof memb_fapl);
+        HDmemset(memb_name, 0, sizeof memb_name);
+        HDmemset(memb_addr, 0, sizeof memb_addr);
+
+        HDassert(HDstrlen(multi_letters)==H5FD_MEM_NTYPES);
+        for(mt = H5FD_MEM_DEFAULT; mt < H5FD_MEM_NTYPES; H5_INC_ENUM(H5FD_mem_t, mt)) {
+          memb_fapl[mt] = H5P_DEFAULT;
+            sprintf(sv[mt], "%%s-%c.h5", multi_letters[mt]);
+            memb_name[mt] = sv[mt];
+            memb_addr[mt] = (haddr_t)MAX(mt - 1, 0) * (HADDR_MAX / 10);
+        } /* end for */
+
+        if (H5Pset_fapl_multi(fapl, memb_map, memb_fapl, memb_name,
+          memb_addr, FALSE)<0) {
+            return -1;
+        }
     } else if (!HDstrcmp(name, "family")) {
         hsize_t fam_size = 100*1024*1024; /*100 MB*/
 
-  /* Family of files, each 1MB and using the default driver */
-  if ((val=HDstrtok(NULL, " \t\n\r")))
-      fam_size = (hsize_t)(HDstrtod(val, NULL) * 1024*1024);
-  if (H5Pset_fapl_family(fapl, fam_size, H5P_DEFAULT)<0)
+        /* Family of files, each 1MB and using the default driver */
+        if ((val=HDstrtok(NULL, " \t\n\r")))
+            fam_size = (hsize_t)(HDstrtod(val, NULL) * 1024*1024);
+        if (H5Pset_fapl_family(fapl, fam_size, H5P_DEFAULT)<0)
             return -1;
     } else if (!HDstrcmp(name, "log")) {
         unsigned log_flags = H5FD_LOG_LOC_IO | H5FD_LOG_ALLOC;
@@ -578,20 +585,21 @@ h5_fileaccess(void)
             log_flags = (unsigned)HDstrtol(val, NULL, 0);
 
         if (H5Pset_fapl_log(fapl, NULL, log_flags, (size_t)0) < 0)
-      return -1;
+            return -1;
     } else if (!HDstrcmp(name, "direct")) {
 #ifdef H5_HAVE_DIRECT
-  /* Linux direct read() and write() system calls.  Set memory boundary, file block size,
-   * and copy buffer size to the default values. */
-  if (H5Pset_fapl_direct(fapl, 1024, 4096, 8*4096)<0) return -1;
+        /* Linux direct read() and write() system calls.  Set memory boundary, file block size,
+         * and copy buffer size to the default values. */
+        if (H5Pset_fapl_direct(fapl, 1024, 4096, 8*4096)<0)
+            return -1;
 #endif
     } else if(!HDstrcmp(name, "latest")) {
-  /* use the latest format */
-  if(H5Pset_libver_bounds(fapl, H5F_LIBVER_LATEST, H5F_LIBVER_LATEST) < 0)
+        /* use the latest format */
+        if(H5Pset_libver_bounds(fapl, H5F_LIBVER_LATEST, H5F_LIBVER_LATEST) < 0)
             return -1;
     } else {
-  /* Unknown driver */
-  return -1;
+        /* Unknown driver */
+        return -1;
     }
 
     return fapl;
diff --git a/test/vfd.c b/test/vfd.c
index b85c054..4ece2ba 100644
--- a/test/vfd.c
+++ b/test/vfd.c
@@ -28,6 +28,7 @@
 #define FAMILY_SIZE2    (5*KB)
 #define MULTI_SIZE      128
 #define CORE_INCREMENT  (4*KB)
+#define CORE_PAGE_SIZE  (1024 * 1024)
 #define DSET1_NAME   "dset1"
 #define DSET1_DIM1   1024
 #define DSET1_DIM2   32
@@ -376,6 +377,8 @@ test_core(void)
     char        filename[1024];
     void        *fhandle=NULL;
     hsize_t     file_size;
+    hbool_t     use_write_tracking;
+    size_t      write_tracking_page_size;
     int    *points = NULL, *check = NULL, *p1, *p2;
     hid_t  dset1=-1, space1=-1;
     hsize_t  dims1[2];
@@ -387,6 +390,8 @@ test_core(void)
     fapl = h5_fileaccess();
     if(H5Pset_fapl_core(fapl, (size_t)CORE_INCREMENT, TRUE) < 0)
         TEST_ERROR;
+    if(H5Pset_core_write_tracking(fapl, TRUE, CORE_PAGE_SIZE) < 0)
+        TEST_ERROR;
     h5_fixname(FILENAME[1], fapl, filename, sizeof filename);
 
     if((file=H5Fcreate(filename, H5F_ACC_TRUNC, H5P_DEFAULT, fapl)) < 0)
@@ -400,6 +405,14 @@ test_core(void)
     if(H5FD_CORE != H5Pget_driver(access_fapl))
         TEST_ERROR;
 
+    /* Check that the backing store write tracking info was saved */
+    if(H5Pget_core_write_tracking(fapl, &use_write_tracking, &write_tracking_page_size) < 0)
+        TEST_ERROR;
+    if(TRUE != use_write_tracking)
+        TEST_ERROR;
+    if(CORE_PAGE_SIZE != write_tracking_page_size)
+        TEST_ERROR;
+
     /* ...and close the property list */
     if (H5Pclose(access_fapl) < 0)
         TEST_ERROR;