[XENBUS PATCH 2/2] balloon: Specify MM_ALLOCATE_PREFER_CONTIGUOUS

["Tu Dinh" <ngoc-tu.dinh@xxxxxxxxxx>]

This flag, available from Windows 7, instructs the kernel allocator to
avoid physical memory fragmentation.

Tested on Server 2022 by decreasing memory from 8GB->5GB:
* Before: 98 balloon allocations containing 6518 contiguous ranges
* After: 98 balloon allocations containing 649 contiguous ranges

Signed-off-by: Tu Dinh <ngoc-tu.dinh@xxxxxxxxxx>
---
 src/xenbus/balloon.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/src/xenbus/balloon.c b/src/xenbus/balloon.c
index 690e45f..e1d0e94 100644
--- a/src/xenbus/balloon.c
+++ b/src/xenbus/balloon.c
@@ -219,6 +219,7 @@ BalloonAllocatePagesForMdl(
                                   TotalBytes,
                                   MmCached,
                                   MM_DONT_ZERO_ALLOCATION |
+                                  MM_ALLOCATE_PREFER_CONTIGUOUS |
                                   MM_ALLOCATE_AND_HOT_REMOVE);
     if (Mdl == NULL)
         goto done;
-- 
2.49.0.windows.1



Ngoc Tu Dinh | Vates XCP-ng Developer

XCP-ng & Xen Orchestra - Vates solutions

web: https://vates.tech