[Xen-changelog] [linux-2.6.18-xen] [IA64] avoid unnecessarily SWIOTLB bounce buffering

["Xen patchbot-linux-2.6.18-xen" <patchbot-linux-2.6.18-xen@xxxxxxxxxxxxxxxxxxx>]

# HG changeset patch
# User Alex Williamson <alex.williamson@xxxxxx>
# Date 1207152177 21600
# Node ID ec6e3e18ea314e9520ee6bba898e30228bf3bda4
# Parent  ad7ad9af265e3276d084f8074192bec9d3867747
[IA64] avoid unnecessarily SWIOTLB bounce buffering

x86 improved range_straddles_page_boundary() by the c/s 501:5486a234923d.
The same discussion applies to ia64. This patch is ia64 counter part of it.

Signed-off-by: Isaku Yamahata <yamahata@xxxxxxxxxxxxx>
---
 arch/ia64/xen/xen_dma.c  |   35 +++++++++++++++++++++++++++++++++++
 include/asm-ia64/maddr.h |   12 +-----------
 2 files changed, 36 insertions(+), 11 deletions(-)

diff -r ad7ad9af265e -r ec6e3e18ea31 arch/ia64/xen/xen_dma.c
--- a/arch/ia64/xen/xen_dma.c   Tue Apr 01 11:29:31 2008 -0600
+++ b/arch/ia64/xen/xen_dma.c   Wed Apr 02 10:02:57 2008 -0600
@@ -37,6 +37,41 @@ do {                                                         
\
        }                                                       \
 } while (0)
 
+static int check_pages_physically_contiguous(unsigned long pfn, 
+                                            unsigned int offset,
+                                            size_t length)
+{
+       unsigned long next_bus;
+       int i;
+       int nr_pages;
+
+       next_bus = pfn_to_mfn_for_dma(pfn);
+       nr_pages = (offset + length + PAGE_SIZE-1) >> PAGE_SHIFT;
+
+       for (i = 1; i < nr_pages; i++) {
+               if (pfn_to_mfn_for_dma(++pfn) != ++next_bus) 
+                       return 0;
+       }
+       return 1;
+}
+
+int range_straddles_page_boundary(paddr_t p, size_t size)
+{
+       extern unsigned long *contiguous_bitmap;
+       unsigned long pfn = p >> PAGE_SHIFT;
+       unsigned int offset = p & ~PAGE_MASK;
+
+       if (!is_running_on_xen())
+               return 0;
+
+       if (offset + size <= PAGE_SIZE)
+               return 0;
+       if (test_bit(pfn, contiguous_bitmap))
+               return 0;
+       if (check_pages_physically_contiguous(pfn, offset, size))
+               return 0;
+       return 1;
+}
 
 /*
  * This should be broken out of swiotlb and put in a common place
diff -r ad7ad9af265e -r ec6e3e18ea31 include/asm-ia64/maddr.h
--- a/include/asm-ia64/maddr.h  Tue Apr 01 11:29:31 2008 -0600
+++ b/include/asm-ia64/maddr.h  Wed Apr 02 10:02:57 2008 -0600
@@ -108,17 +108,7 @@ typedef unsigned long paddr_t;
 #endif
 
 #ifdef CONFIG_XEN
-static inline int
-range_straddles_page_boundary(paddr_t p, size_t size)
-{
-       extern unsigned long *contiguous_bitmap;
-
-       if (!is_running_on_xen())
-               return 0;
-
-       return ((((p & ~PAGE_MASK) + size) > PAGE_SIZE) &&
-               !test_bit(p >> PAGE_SHIFT, contiguous_bitmap));
-}
+int range_straddles_page_boundary(paddr_t p, size_t size);
 #else
 #define range_straddles_page_boundary(addr, size)      (0)
 #endif

_______________________________________________
Xen-changelog mailing list
Xen-changelog@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-changelog