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Re: [Xen-devel] [PATCH 1 of 4] p2m: Keep statistics on order of p2m entr

To: <xen-devel@xxxxxxxxxxxxxxxxxxx>
Subject: Re: [Xen-devel] [PATCH 1 of 4] p2m: Keep statistics on order of p2m entries
From: Christoph Egger <Christoph.Egger@xxxxxxx>
Date: Fri, 6 May 2011 16:40:01 +0200
Delivery-date: Fri, 06 May 2011 07:51:51 -0700
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Hi,

Can you please use defines for the indexes of p2m->stats.entries[], please? That makes it easier to read what you are counting.

Christoph


On 05/06/11 16:01, George Dunlap wrote:
Count the number of 4kiB, 2MiB, and 1GiB p2m entries.

Signed-off-by: George Dunlap<george.dunlap@xxxxxxxxxxxxx>

diff -r 4b0692880dfa -r be5d93d38f28 xen/arch/x86/mm/hap/p2m-ept.c
--- a/xen/arch/x86/mm/hap/p2m-ept.c     Thu May 05 17:40:34 2011 +0100
+++ b/xen/arch/x86/mm/hap/p2m-ept.c     Fri May 06 15:01:08 2011 +0100
@@ -39,6 +39,8 @@

  #define is_epte_present(ept_entry)      ((ept_entry)->epte&  0x7)
  #define is_epte_superpage(ept_entry)    ((ept_entry)->sp)
+#define is_epte_countable(ept_entry)    (is_epte_present(ept_entry) \
+                                         || ((ept_entry)->sa_p2mt == 
p2m_populate_on_demand))

  /* Non-ept "lock-and-check" wrapper */
  static int ept_pod_check_and_populate(struct p2m_domain *p2m, unsigned long 
gfn,
@@ -167,11 +169,14 @@
  void ept_free_entry(struct p2m_domain *p2m, ept_entry_t *ept_entry, int level)
  {
      /* End if the entry is a leaf entry. */
-    if ( level == 0 || !is_epte_present(ept_entry) ||
-         is_epte_superpage(ept_entry) )
+    if ( level == 0 || !is_epte_present(ept_entry) || 
is_epte_superpage(ept_entry) )
+    {
+        if ( is_epte_countable(ept_entry) )
+            p2m->stats.entries[level]--;
          return;
+    }

-    if ( level>  1 )
+    if ( level>  0 )
      {
          ept_entry_t *epte = map_domain_page(ept_entry->mfn);
          for ( int i = 0; i<  EPT_PAGETABLE_ENTRIES; i++ )
@@ -217,7 +222,10 @@
          ept_p2m_type_to_flags(epte, epte->sa_p2mt, epte->access);

          if ( (level - 1) == target )
+        {
+            p2m->stats.entries[target]++;
              continue;
+        }

          ASSERT(is_epte_superpage(epte));

@@ -400,6 +408,10 @@
              ept_p2m_type_to_flags(&new_entry, p2mt, p2ma);
          }

+        /* old_entry will be handled by ept_free_entry below */
+        if ( is_epte_countable(&new_entry) )
+            p2m->stats.entries[i]++;
+
          atomic_write_ept_entry(ept_entry, new_entry);
      }
      else
@@ -412,12 +424,16 @@

          split_ept_entry = atomic_read_ept_entry(ept_entry);

+        /* Accounting should be OK here; split_ept_entry bump the counts,
+         * free_entry will reduce them. */
          if ( !ept_split_super_page(p2m,&split_ept_entry, i, target) )
          {
              ept_free_entry(p2m,&split_ept_entry, i);
              goto out;
          }

+        /* We know this was countable or we wouldn't be here.*/
+        p2m->stats.entries[i]--;
          /* now install the newly split ept sub-tree */
          /* NB: please make sure domian is paused and no in-fly VT-d DMA. */
          atomic_write_ept_entry(ept_entry, split_ept_entry);
@@ -449,9 +465,13 @@

          ept_p2m_type_to_flags(&new_entry, p2mt, p2ma);

+        /* old_entry will be handled by ept_free_entry below */
+        if ( is_epte_countable(&new_entry) )
+            p2m->stats.entries[i]++;
+
          atomic_write_ept_entry(ept_entry, new_entry);
      }
-
+
      /* Track the highest gfn for which we have ever had a valid mapping */
      if ( mfn_valid(mfn_x(mfn))&&
           (gfn + (1UL<<  order) - 1>  p2m->max_mapped_pfn) )
diff -r 4b0692880dfa -r be5d93d38f28 xen/arch/x86/mm/p2m.c
--- a/xen/arch/x86/mm/p2m.c     Thu May 05 17:40:34 2011 +0100
+++ b/xen/arch/x86/mm/p2m.c     Fri May 06 15:01:08 2011 +0100
@@ -184,11 +184,15 @@
  {
      /* End if the entry is a leaf entry. */
      if ( page_order == 0
-         || !(l1e_get_flags(*p2m_entry)&  _PAGE_PRESENT)
+         || !(l1e_get_flags(*p2m_entry)&  _PAGE_PRESENT)
           || (l1e_get_flags(*p2m_entry)&  _PAGE_PSE) )
+    {
+        if ( l1e_get_flags(*p2m_entry) )
+            p2m->stats.entries[page_order/9]--;
          return;
-
-    if ( page_order>  9 )
+    }
+
+    if ( page_order )
      {
          l1_pgentry_t *l3_table = map_domain_page(l1e_get_pfn(*p2m_entry));
          for ( int i = 0; i<  L3_PAGETABLE_ENTRIES; i++ )
@@ -242,6 +246,7 @@
          new_entry = l1e_from_pfn(mfn_x(page_to_mfn(pg)),
                                   __PAGE_HYPERVISOR | _PAGE_USER);

+        /* Stats: Empty entry, no mods needed */
          switch ( type ) {
          case PGT_l3_page_table:
              p2m_add_iommu_flags(&new_entry, 3, 
IOMMUF_readable|IOMMUF_writable);
@@ -285,10 +290,12 @@
          {
              new_entry = l1e_from_pfn(pfn + (i * L1_PAGETABLE_ENTRIES), flags);
              p2m_add_iommu_flags(&new_entry, 1, 
IOMMUF_readable|IOMMUF_writable);
+            p2m->stats.entries[1]++;
              p2m->write_p2m_entry(p2m, gfn,
                  l1_entry+i, *table_mfn, new_entry, 2);
          }
          unmap_domain_page(l1_entry);
+        p2m->stats.entries[2]--;
          new_entry = l1e_from_pfn(mfn_x(page_to_mfn(pg)),
                                   __PAGE_HYPERVISOR|_PAGE_USER); //disable PSE
          p2m_add_iommu_flags(&new_entry, 2, IOMMUF_readable|IOMMUF_writable);
@@ -320,6 +327,7 @@
          {
              new_entry = l1e_from_pfn(pfn + i, flags);
              p2m_add_iommu_flags(&new_entry, 0, 0);
+            p2m->stats.entries[0]++;
              p2m->write_p2m_entry(p2m, gfn,
                  l1_entry+i, *table_mfn, new_entry, 1);
          }
@@ -328,6 +336,7 @@
          new_entry = l1e_from_pfn(mfn_x(page_to_mfn(pg)),
                                   __PAGE_HYPERVISOR|_PAGE_USER);
          p2m_add_iommu_flags(&new_entry, 1, IOMMUF_readable|IOMMUF_writable);
+        p2m->stats.entries[1]--;
          p2m->write_p2m_entry(p2m, gfn,
              p2m_entry, *table_mfn, new_entry, 2);
      }
@@ -908,6 +917,15 @@
  void
  p2m_pod_dump_data(struct p2m_domain *p2m)
  {
+    int i;
+    long entries;
+    printk("    P2M entry stats:\n");
+    for ( i=0; i<3; i++)
+        if ( (entries=p2m->stats.entries[i]) )
+            printk("     L%d: %8ld entries, %ld bytes\n",
+                   i+1,
+                   entries,
+                   entries<<(i*9+12));
      printk("    PoD entries=%d cachesize=%d\n",
             p2m->pod.entry_count, p2m->pod.count);
  }
@@ -1475,6 +1493,12 @@
              old_mfn = l1e_get_pfn(*p2m_entry);
          }

+        /* Adjust count for present/not-present entries added */
+        if ( l1e_get_flags(*p2m_entry) )
+            p2m->stats.entries[page_order/9]--;
+        if ( l1e_get_flags(entry_content) )
+            p2m->stats.entries[page_order/9]++;
+
          p2m->write_p2m_entry(p2m, gfn, p2m_entry, table_mfn, entry_content, 
3);
          /* NB: paging_write_p2m_entry() handles tlb flushes properly */

@@ -1519,6 +1543,13 @@
              p2m_add_iommu_flags(&entry_content, 0, iommu_pte_flags);
              old_mfn = l1e_get_pfn(*p2m_entry);
          }
+
+        /* Adjust count for present/not-present entries added */
+        if ( l1e_get_flags(*p2m_entry) )
+            p2m->stats.entries[page_order/9]--;
+        if ( l1e_get_flags(entry_content) )
+            p2m->stats.entries[page_order/9]++;
+
          /* level 1 entry */
          p2m->write_p2m_entry(p2m, gfn, p2m_entry, table_mfn, entry_content, 
1);
          /* NB: paging_write_p2m_entry() handles tlb flushes properly */
@@ -1556,6 +1587,12 @@
              old_mfn = l1e_get_pfn(*p2m_entry);
          }

+        /* Adjust count for present/not-present entries added */
+        if ( l1e_get_flags(*p2m_entry) )
+            p2m->stats.entries[page_order/9]--;
+        if ( l1e_get_flags(entry_content) )
+            p2m->stats.entries[page_order/9]++;
+
          p2m->write_p2m_entry(p2m, gfn, p2m_entry, table_mfn, entry_content, 
2);
          /* NB: paging_write_p2m_entry() handles tlb flushes properly */

@@ -2750,6 +2787,8 @@
                  continue;
              }

+            /* STATS: Should change only type; no stats should need adjustment 
*/
+
              l2mfn = _mfn(l3e_get_pfn(l3e[i3]));
              l2e = map_domain_page(l3e_get_pfn(l3e[i3]));
              for ( i2 = 0; i2<  L2_PAGETABLE_ENTRIES; i2++ )
diff -r 4b0692880dfa -r be5d93d38f28 xen/include/asm-x86/p2m.h
--- a/xen/include/asm-x86/p2m.h Thu May 05 17:40:34 2011 +0100
+++ b/xen/include/asm-x86/p2m.h Fri May 06 15:01:08 2011 +0100
@@ -278,6 +278,10 @@
          unsigned         reclaim_single; /* Last gpfn of a scan */
          unsigned         max_guest;    /* gpfn of max guest demand-populate */
      } pod;
+
+    struct {
+        long entries[3];
+    } stats;
  };

  /* get host p2m table */

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