[ros-diffs] [ros-arm-bringup] 41859: - Implement a simple nonpaged pool page allocator and deallocator: - Not actually used yet! - No support for expansion nonpaged pool yet. - No major optimizations. - We simply do the sane thing of trying to combine the next free allocation with the one we're about to make, on free. - If possible, we'll also check if the previous allocation was a free block, and we'll merge ourselves (and in the best case, whoever is following us) into that block instead. - No debug check

Author: ros-arm-bringup
Date: Sat Jul 11 10:46:39 2009
New Revision: 41859
URL: http://svn.reactos.org/svn/reactos?rev=41859&view=rev
Log:
- Implement a simple nonpaged pool page allocator and deallocator:
  - Not actually used yet!
  - No support for expansion nonpaged pool yet.
  - No major optimizations.
    - We simply do the sane thing of trying to combine the next free allocation with the
one we're about to make, on free.
      - If possible, we'll also check if the previous allocation was a free block, and
we'll merge ourselves (and in the best case, whoever is following us) into that block
instead.
  - No debug checks/validation.
- Write a couple lines of code to allocate and free up to 4096 pages (it will stop when it
runs out).
  - This is to properly excercise this code on everyone's machines to make sure it
works fine (it adds a little delay to booting, but only temporary).
Modified:
    trunk/reactos/ntoskrnl/mm/ARM3/init.c
    trunk/reactos/ntoskrnl/mm/ARM3/pool.c
Modified: trunk/reactos/ntoskrnl/mm/ARM3/init.c
URL:
http://svn.reactos.org/svn/reactos/trunk/reactos/ntoskrnl/mm/ARM3/init.c?re…
==============================================================================
--- trunk/reactos/ntoskrnl/mm/ARM3/init.c [iso-8859-1] (original)
+++ trunk/reactos/ntoskrnl/mm/ARM3/init.c [iso-8859-1] Sat Jul 11 10:46:39 2009
@@ -714,6 +714,26 @@
         // Initialize the nonpaged pool
         //
         InitializePool(NonPagedPool, 0);
+
+        //
+        // Do a little test of the nonpaged pool allocator
+        //
+        if (1)
+        {
+            ULONG i = 0;
+            PVOID Buffers[4096];
+            while (TRUE)
+            {
+                Buffers[i] = MiAllocatePoolPages(NonPagedPool, PAGE_SIZE);
+                if (!Buffers[i]) break;
+                i++;
+            }
+
+            while (i--)
+            {
+                MiFreePoolPages(Buffers[i]);
+            }
+        }
     }
     else
     {
Modified: trunk/reactos/ntoskrnl/mm/ARM3/pool.c
URL:
http://svn.reactos.org/svn/reactos/trunk/reactos/ntoskrnl/mm/ARM3/pool.c?re…
==============================================================================
--- trunk/reactos/ntoskrnl/mm/ARM3/pool.c [iso-8859-1] (original)
+++ trunk/reactos/ntoskrnl/mm/ARM3/pool.c [iso-8859-1] Sat Jul 11 10:46:39 2009
@@ -125,4 +125,395 @@
                            NonPagedPoolExpansion);
 }
+PVOID
+NTAPI
+MiAllocatePoolPages(IN POOL_TYPE PoolType,
+                    IN SIZE_T SizeInBytes)
+{
+    PFN_NUMBER SizeInPages;
+    ULONG i;
+    KIRQL OldIrql;
+    PLIST_ENTRY NextEntry, NextHead, LastHead;
+    PMMPTE PointerPte;
+    PMMPFN Pfn1;
+    PVOID BaseVa;
+    PMMFREE_POOL_ENTRY FreeEntry;
+
+    //
+    // Figure out how big the allocation is in pages
+    //
+    SizeInPages = BYTES_TO_PAGES(SizeInBytes);
+
+    //
+    // Allocations of less than 4 pages go into their individual buckets
+    //
+    i = SizeInPages - 1;
+    if (i >= MI_MAX_FREE_PAGE_LISTS) i = MI_MAX_FREE_PAGE_LISTS - 1;
+
+    //
+    // Loop through all the free page lists based on the page index
+    //
+    NextHead = &MmNonPagedPoolFreeListHead[i];
+    LastHead = &MmNonPagedPoolFreeListHead[MI_MAX_FREE_PAGE_LISTS];
+
+    //
+    // Acquire the nonpaged pool lock
+    //
+    OldIrql = KeAcquireQueuedSpinLock(LockQueueMmNonPagedPoolLock);
+    do
+    {
+        //
+        // Now loop through all the free page entries in this given list
+        //
+        NextEntry = NextHead->Flink;
+        while (NextEntry != NextHead)
+        {
+            //
+            // Grab the entry and see if it can handle our allocation
+            //
+            FreeEntry = CONTAINING_RECORD(NextEntry, MMFREE_POOL_ENTRY, List);
+            if (FreeEntry->Size >= SizeInPages)
+            {
+                //
+                // It does, so consume the pages from here
+                //
+                FreeEntry->Size -= SizeInPages;
+
+                //
+                // The allocation will begin in this free page area
+                //
+                BaseVa = (PVOID)((ULONG_PTR)FreeEntry +
+                                 (FreeEntry->Size  << PAGE_SHIFT));
+
+                //
+                // This is not a free page segment anymore
+                //
+                RemoveEntryList(&FreeEntry->List);
+
+                //
+                // However, check if its' still got space left
+                //
+                if (FreeEntry->Size != 0)
+                {
+                    //
+                    // Insert it back into a different list, based on its pages
+                    //
+                    i = FreeEntry->Size - 1;
+                    if (i >= MI_MAX_FREE_PAGE_LISTS) i = MI_MAX_FREE_PAGE_LISTS - 1;
+                    InsertTailList (&MmNonPagedPoolFreeListHead[i],
+                                    &FreeEntry->List);
+                }
+
+                //
+                // Grab the PTE for this allocation
+                //
+                PointerPte = MiAddressToPte(BaseVa);
+                ASSERT(PointerPte->u.Hard.Valid == 1);
+
+                //
+                // Grab the PFN NextEntry and index
+                //
+                Pfn1 = MiGetPfnEntry(PFN_FROM_PTE(PointerPte));
+
+                //
+                // Now mark it as the beginning of an allocation
+                //
+                ASSERT(Pfn1->u3.e1.StartOfAllocation == 0);
+                Pfn1->u3.e1.StartOfAllocation = 1;
+
+                //
+                // Check if the allocation is larger than one page
+                //
+                if (SizeInPages != 1)
+                {
+                    //
+                    // Navigate to the last PFN entry and PTE
+                    //
+                    PointerPte += SizeInPages - 1;
+                    ASSERT(PointerPte->u.Hard.Valid == 1);
+                    Pfn1 = MiGetPfnEntry(PointerPte->u.Hard.PageFrameNumber);
+                }
+
+                //
+                // Mark this PFN as the last (might be the same as the first)
+                //
+                ASSERT(Pfn1->u3.e1.EndOfAllocation == 0);
+                Pfn1->u3.e1.EndOfAllocation = 1;
+
+                //
+                // Release the nonpaged pool lock, and return the allocation
+                //
+                KeReleaseQueuedSpinLock(LockQueueMmNonPagedPoolLock, OldIrql);
+                return BaseVa;
+            }
+
+            //
+            // Try the next free page entry
+            //
+            NextEntry = FreeEntry->List.Flink;
+        }
+    } while (++NextHead < LastHead);
+
+    //
+    // If we got here, we're out of space.
+    // Start by releasing the lock
+    //
+    KeReleaseQueuedSpinLock (LockQueueMmNonPagedPoolLock, OldIrql);
+
+    //
+    // We should now go into expansion nonpaged pool
+    //
+    DPRINT1("Out of NP Pool\n");
+    return NULL;
+}
+
+ULONG
+NTAPI
+MiFreePoolPages(IN PVOID StartingVa)
+{
+    PMMPTE PointerPte, StartPte;
+    PMMPFN Pfn1, StartPfn;
+    PFN_NUMBER FreePages, NumberOfPages;
+    KIRQL OldIrql;
+    PMMFREE_POOL_ENTRY FreeEntry, NextEntry, LastEntry;
+    ULONG i;
+
+    //
+    // Get the first PTE and its corresponding PFN entry
+    //
+    StartPte = PointerPte = MiAddressToPte(StartingVa);
+    StartPfn = Pfn1 = MiGetPfnEntry(PointerPte->u.Hard.PageFrameNumber);
+
+    //
+    // Loop until we find the last PTE
+    //
+    while (Pfn1->u3.e1.EndOfAllocation == 0)
+    {
+        //
+        // Keep going
+        //
+        PointerPte++;
+        Pfn1 = MiGetPfnEntry(PointerPte->u.Hard.PageFrameNumber);
+    }
+
+    //
+    // Now we know how many pages we have
+    //
+    NumberOfPages = PointerPte - StartPte + 1;
+
+    //
+    // Acquire the nonpaged pool lock
+    //
+    OldIrql = KeAcquireQueuedSpinLock(LockQueueMmNonPagedPoolLock);
+
+    //
+    // Mark the first and last PTEs as not part of an allocation anymore
+    //
+    StartPfn->u3.e1.StartOfAllocation = 0;
+    Pfn1->u3.e1.EndOfAllocation = 0;
+
+    //
+    // Assume we will free as many pages as the allocation was
+    //
+    FreePages = NumberOfPages;
+
+    //
+    // Peek one page past the end of the allocation
+    //
+    PointerPte++;
+
+    //
+    // Guard against going past initial nonpaged pool
+    //
+    if (MiGetPfnEntryIndex(Pfn1) == MiEndOfInitialPoolFrame)
+    {
+        //
+        // This page is on the outskirts of initial nonpaged pool, so ignore it
+        //
+        DPRINT1("End of initial frame\n");
+        Pfn1 = NULL;
+    }
+    else
+    {
+        //
+        // Otherwise, our entire allocation must've fit within the initial non
+        // paged pool, or the expansion nonpaged pool, so get the PFN entry of
+        // the next allocation
+        //
+        ASSERT((ULONG_PTR)StartingVa + NumberOfPages <= (ULONG_PTR)MmNonPagedPoolEnd);
+        if (PointerPte->u.Hard.Valid == 1)
+        {
+            //
+            // It's either expansion or initial: get the PFN entry
+            //
+            Pfn1 = MiGetPfnEntry(PointerPte->u.Hard.PageFrameNumber);
+        }
+        else
+        {
+            //
+            // This means we've reached the guard page that protects the end of
+            // the expansion nonpaged pool
+            //
+            Pfn1 = NULL;
+        }
+
+    }
+
+    //
+    // Check if this allocation actually exists
+    //
+    if ((Pfn1) && (Pfn1->u3.e1.StartOfAllocation == 0))
+    {
+        //
+        // It doesn't, so we should actually locate a free entry descriptor
+        //
+        FreeEntry = (PMMFREE_POOL_ENTRY)((ULONG_PTR)StartingVa +
+                                         (NumberOfPages << PAGE_SHIFT));
+        ASSERT(FreeEntry->Owner == FreeEntry);
+
+        //
+        // Consume this entry's pages, and remove it from its free list
+        //
+        FreePages += FreeEntry->Size;
+        RemoveEntryList (&FreeEntry->List);
+    }
+
+    //
+    // Now get the official free entry we'll create for the caller's allocation
+    //
+    FreeEntry = StartingVa;
+
+    //
+    // Check if the our allocation is the very first page
+    //
+    if (MiGetPfnEntryIndex(StartPfn) == MiStartOfInitialPoolFrame)
+    {
+        //
+        // Then we can't do anything or we'll risk underflowing
+        //
+        DPRINT1("Start of of initial frame\n");
+        Pfn1 = NULL;
+    }
+    else
+    {
+        //
+        // Otherwise, get the PTE for the page right before our allocation
+        //
+        PointerPte -= NumberOfPages + 1;
+        if (PointerPte->u.Hard.Valid == 1)
+        {
+            //
+            // It's either expansion or initial nonpaged pool, get the PFN entry
+            //
+            Pfn1 = MiGetPfnEntry(PointerPte->u.Hard.PageFrameNumber);
+        }
+        else
+        {
+            //
+            // We must've reached the guard page, so don't risk touching it
+            //
+            Pfn1 = NULL;
+        }
+    }
+
+    //
+    // Check if there is a valid PFN entry for the page before the allocation
+    // and then check if this page was actually the end of an allocation.
+    // If it wasn't, then we know for sure it's a free page
+    //
+    if ((Pfn1) && (Pfn1->u3.e1.EndOfAllocation == 0))
+    {
+        //
+        // Get the free entry descriptor for that given page range
+        //
+        FreeEntry = (PMMFREE_POOL_ENTRY)((ULONG_PTR)StartingVa - PAGE_SIZE);
+        FreeEntry = FreeEntry->Owner;
+
+        //
+        // Check if the entry is small enough to be indexed on a free list
+        // If it is, we'll want to re-insert it, since we're about to
+        // collapse our pages on top of it, which will change its count
+        //
+        if (FreeEntry->Size < (MI_MAX_FREE_PAGE_LISTS - 1))
+        {
+            //
+            // Remove the list from where it is now
+            //
+            RemoveEntryList(&FreeEntry->List);
+
+            //
+            // Update its size
+            //
+            FreeEntry->Size += FreePages;
+
+            //
+            // And now find the new appropriate list to place it in
+            //
+            i = (ULONG)(FreeEntry->Size - 1);
+            if (i >= MI_MAX_FREE_PAGE_LISTS) i = MI_MAX_FREE_PAGE_LISTS - 1;
+
+            //
+            // Do it
+            //
+            InsertTailList(&MmNonPagedPoolFreeListHead[i], &FreeEntry->List);
+        }
+        else
+        {
+            //
+            // Otherwise, just combine our free pages into this entry
+            //
+            FreeEntry->Size += FreePages;
+        }
+    }
+
+    //
+    // Check if we were unable to do any compaction, and we'll stick with this
+    //
+    if (FreeEntry == StartingVa)
+    {
+        //
+        // Well, now we are a free entry. At worse we just have our newly freed
+        // pages, at best we have our pages plus whatever entry came after us
+        //
+        FreeEntry->Size = FreePages;
+
+        //
+        // Find the appropriate list we should be on
+        //
+        i = FreeEntry->Size - 1;
+        if (i >= MI_MAX_FREE_PAGE_LISTS) i = MI_MAX_FREE_PAGE_LISTS - 1;
+
+        //
+        // And insert us
+        //
+        InsertTailList (&MmNonPagedPoolFreeListHead[i], &FreeEntry->List);
+    }
+
+    //
+    // Just a sanity check
+    //
+    ASSERT(FreePages != 0);
+
+    //
+    // Get all the pages between our allocation and its end. These will all now
+    // become free page chunks.
+    //
+    NextEntry = StartingVa;
+    LastEntry = (PMMFREE_POOL_ENTRY)((ULONG_PTR)NextEntry + (FreePages <<
PAGE_SHIFT));
+    do
+    {
+        //
+        // Link back to the parent free entry, and keep going
+        //
+        NextEntry->Owner = FreeEntry;
+        NextEntry = (PMMFREE_POOL_ENTRY)((ULONG_PTR)NextEntry + PAGE_SIZE);
+    } while (NextEntry != LastEntry);
+
+    //
+    // We're done, release the lock and let the caller know how much we freed
+    //
+    KeReleaseQueuedSpinLock(LockQueueMmNonPagedPoolLock, OldIrql);
+    return NumberOfPages;
+}
+
 /* EOF */