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


  • To: Christoph Egger <Christoph.Egger@xxxxxxx>
  • From: George Dunlap <dunlapg@xxxxxxxxx>
  • Date: Fri, 6 May 2011 16:34:46 +0100
  • Cc: "xen-devel@xxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxx>, Tim Deegan <Tim.Deegan@xxxxxxxxxx>
  • Delivery-date: Fri, 06 May 2011 08:35:27 -0700
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On Fri, May 6, 2011 at 3:53 PM, Christoph Egger <Christoph.Egger@xxxxxxx> wrote:
> What about this:
>
> #define PAGE_ORDER_4K  0
> #define PAGE_ORDER_2M  9
> #define PAGE_ORDER_1G  18

That would be 0, 1, and 2, respectively.  I had thought about
something like this, but the common usage seems to be to use L1-3
rather than 4k, 2M, or 1G; and

#define PAGE_ORDER_L1 0
#define PAGE_ORDER_L2 1
#define PAGE_ORDER_L3 2

seemed a bit redundant.

This patch is actually not necessary for the series -- just for the
verification that it worked.  I could drop this patch so we can
discuss it, and send the other three by themselves (since they seem
pretty uncontroversial).

 -George

>
>>
>> On the other hand, maybe the array itself could have a more descriptive
>> name than "stats.entries".
>>
>> Tim.
>>
>>> 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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