Index: src/lsm_file.c
==================================================================
--- src/lsm_file.c
+++ src/lsm_file.c
@@ -243,12 +243,10 @@
   int nCacheAlloc;                /* Current cache size (in pages) */
   Page *pLruFirst;                /* Head of the LRU list */
   Page *pLruLast;                 /* Tail of the LRU list */
   int nHash;                      /* Number of hash slots in hash table */
   Page **apHash;                  /* nHash Hash slots */
-
-  /* Both types of pages */
   Page *pWaiting;                 /* b-tree pages waiting to be written */
 
   /* Statistics */
   int nOut;                       /* Number of outstanding pages */
   int nWrite;                     /* Total number of pages written */
@@ -979,10 +977,16 @@
   for(pp=&pFS->apHash[iHash]; *pp!=pPg; pp=&(*pp)->pHashNext);
   *pp = pPg->pHashNext;
   pPg->pHashNext = 0;
 }
 
+static void fsPageBufferFree(Page *pPg){
+  pPg->pFS->nCacheAlloc--;
+  lsmFree(pPg->pFS->pEnv, pPg->aData);
+  lsmFree(pPg->pFS->pEnv, pPg);
+}
+
 
 /*
 ** Purge the cache of all non-mmap pages with nRef==0.
 */
 void lsmFsPurgeCache(FileSystem *pFS){
@@ -991,14 +995,12 @@
   pPg = pFS->pLruFirst;
   while( pPg ){
     Page *pNext = pPg->pLruNext;
     assert( pPg->flags & PAGE_FREE );
     fsPageRemoveFromHash(pFS, pPg);
-    lsmFree(pFS->pEnv, pPg->aData);
-    lsmFree(pFS->pEnv, pPg);
+    fsPageBufferFree(pPg);
     pPg = pNext;
-    pFS->nCacheAlloc--;
   }
   pFS->pLruFirst = 0;
   pFS->pLruLast = 0;
 
   assert( pFS->nCacheAlloc<=pFS->nOut && pFS->nCacheAlloc>=0 );
@@ -1062,20 +1064,10 @@
   }
   *ppOut = pPage;
   return rc;
 }
 
-static void fsPageBufferFree(Page *pPg){
-  assert( pPg->pLruNext==0 );
-  assert( pPg->pLruPrev==0 );
-  assert( pPg->pFS->pLruFirst!=pPg );
-  assert( pPg->pFS->pLruLast!=pPg );
-
-  lsmFree(pPg->pFS->pEnv, pPg->aData);
-  lsmFree(pPg->pFS->pEnv, pPg);
-}
-
 static void fsGrowMapping(
   FileSystem *pFS,
   i64 iSz,
   int *pRc
 ){

Index: src/lsm_unix.c
==================================================================
--- src/lsm_unix.c
+++ src/lsm_unix.c
@@ -200,10 +200,15 @@
   off_t iSz;
   int prc;
   PosixFile *p = (PosixFile *)pFile;
   struct stat buf;
 
+  /* If the file is between 0 and 2MB in size, extend it in chunks of 256K.
+  ** Thereafter, in chunks of 1MB at a time.  */
+  const int aIncrSz[] = {256*1024, 1024*1024};
+  int nIncrSz = aIncrSz[iMin>(2*1024*1024)];
+
   if( p->pMap ){
     munmap(p->pMap, p->nMap);
     *ppOut = p->pMap = 0;
     *pnOut = p->nMap = 0;
   }
@@ -212,11 +217,11 @@
     memset(&buf, 0, sizeof(buf));
     prc = fstat(p->fd, &buf);
     if( prc!=0 ) return LSM_IOERR_BKPT;
     iSz = buf.st_size;
     if( iSz<iMin ){
-      iSz = ((iMin + (2<<20) - 1) / (2<<20)) * (2<<20);
+      iSz = ((iMin + nIncrSz-1) / nIncrSz) * nIncrSz;
       prc = ftruncate(p->fd, iSz);
       if( prc!=0 ) return LSM_IOERR_BKPT;
     }
 
     p->pMap = mmap(0, iSz, PROT_READ|PROT_WRITE, MAP_SHARED, p->fd, 0);