[Xen-changelog] [xen-unstable] x86: add perf counter for pointless updates of writable pages through a hypercall

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

# HG changeset patch
# User Keir Fraser <keir.fraser@xxxxxxxxxx>
# Date 1213283499 -3600
# Node ID 882eb6186c2dbc7f73280f3aca3600faad44fbf0
# Parent  a3319f32496fd93a545fc354ce3944072cc32e5e
x86: add perf counter for pointless updates of writable pages through a 
hypercall
Signed-off-by: Jan Beulich <jbeulich@xxxxxxxxxx>
---
 xen/arch/x86/mm.c                |    2 ++
 xen/include/asm-x86/perfc_defn.h |    1 +
 2 files changed, 3 insertions(+)

diff -r a3319f32496f -r 882eb6186c2d xen/arch/x86/mm.c
--- a/xen/arch/x86/mm.c Thu Jun 12 16:09:08 2008 +0100
+++ b/xen/arch/x86/mm.c Thu Jun 12 16:11:39 2008 +0100
@@ -2602,6 +2602,8 @@ int do_mmu_update(
                 if ( unlikely(!get_page_type(page, PGT_writable_page)) )
                     break;
 
+                perfc_incr(writable_mmu_updates);
+
                 okay = paging_write_guest_entry(v, va, req.val, _mfn(mfn));
 
                 put_page_type(page);
diff -r a3319f32496f -r 882eb6186c2d xen/include/asm-x86/perfc_defn.h
--- a/xen/include/asm-x86/perfc_defn.h  Thu Jun 12 16:09:08 2008 +0100
+++ b/xen/include/asm-x86/perfc_defn.h  Thu Jun 12 16:11:39 2008 +0100
@@ -23,6 +23,7 @@ PERFCOUNTER(num_mmuext_ops,             
 PERFCOUNTER(num_mmuext_ops,             "mmuext ops")
 PERFCOUNTER(calls_to_mmu_update,        "calls to mmu_update")
 PERFCOUNTER(num_page_updates,           "page updates")
+PERFCOUNTER(writable_mmu_updates,       "mmu_updates of writable pages")
 PERFCOUNTER(calls_to_update_va,         "calls to update_va_map")
 PERFCOUNTER(page_faults,            "page faults")
 PERFCOUNTER(copy_user_faults,       "copy_user faults")

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