[Xen-changelog] [xen-unstable] [XEND] Be more generous with the default shadow allocation.

[Xen patchbot-unstable <patchbot-unstable@xxxxxxxxxxxxxxxxxxx>]

# HG changeset patch
# User Tim Deegan <Tim.Deegan@xxxxxxxxxxxxx>
# Node ID 09aa7ed2431fa7a820a843f126bb6a4f8e3fbeef
# Parent  f61dcd518cd69d047f2cf97209f88c1092904b29
[XEND] Be more generous with the default shadow allocation.
Allow enough shadow memory to avoid thrashing the shadow pages,
rather than just enough for safety.
Signed-off-by: Tim Deegan <Tim.Deegan@xxxxxxxxxxxxx>
---
 tools/python/xen/xend/image.py |    9 ++++++---
 1 files changed, 6 insertions(+), 3 deletions(-)

diff -r f61dcd518cd6 -r 09aa7ed2431f tools/python/xen/xend/image.py
--- a/tools/python/xen/xend/image.py    Wed Oct 25 10:27:03 2006 +0100
+++ b/tools/python/xen/xend/image.py    Wed Oct 25 11:44:58 2006 +0100
@@ -500,9 +500,12 @@ class X86_HVM_ImageHandler(HVMImageHandl
         # overhead due to getRequiredInitialReservation.
         maxmem_kb = self.getRequiredInitialReservation(maxmem_kb)
 
-        # 1MB per vcpu plus 4Kib/Mib of RAM.  This is higher than 
-        # the minimum that Xen would allocate if no value were given.
-        return max(1024 * self.vm.getVCpuCount() + maxmem_kb / 256,
+        # 256 pages (1MB) per vcpu,
+        # plus 1 page per MiB of RAM for the P2M map,
+        # plus 1 page per MiB of RAM to shadow the resident processes.  
+        # This is higher than the minimum that Xen would allocate if no value 
+        # were given (but the Xen minimum is for safety, not performance).
+        return max(4 * (256 * self.vm.getVCpuCount() + 2 * (maxmem_kb / 1024)),
                    shadow_mem_kb)
 
 

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