Re: [PATCH v1] KVM: stats: Add VM stat for the cumulative number of dirtied pages

On Wed, Aug 11, 2021 at 4:53 PM Oliver Upton <[email protected]> wrote:
>
> Hi Jing,
>
> Tiny nit (doesn't need to be addressed for this patch): when
> respinning a patch, start from 'v2'. The original patch (without
> versioning) is v1.
Got it.
>
> On Wed, Aug 11, 2021 at 4:37 PM Jing Zhang <[email protected]> wrote:
> >
> > A per VM stat dirty_pages is added to record the number of dirtied pages
> > in the life cycle of a VM.
> > The growth rate of this stat is a good indicator during the process of
> > live migrations. The exact number of dirty pages at the moment doesn't
> > matter. That's why we define dirty_pages as a cumulative counter instead
> > of an instantaneous one.
> >
> > Original-by: Peter Feiner <[email protected]>
> > Suggested-by: Oliver Upton <[email protected]>
> > Signed-off-by: Jing Zhang <[email protected]>
>
> Besides the comment below:
>
> Reviewed-by: Oliver Upton <[email protected]>
>
> Also make sure this builds on PPC (follow up offline if you need to
> know how to do it with our tools), as I believe testing automation
> flagged your last spin.
>
> Thanks!
>
> --
> Oliver
>
> > ---
> >  arch/powerpc/include/asm/kvm_book3s.h  |  3 ++-
> >  arch/powerpc/kvm/book3s_64_mmu_hv.c    | 10 +++++++---
> >  arch/powerpc/kvm/book3s_64_mmu_radix.c |  3 ++-
> >  arch/powerpc/kvm/book3s_hv_rm_mmu.c    | 13 ++++++++-----
> >  include/linux/kvm_host.h               |  3 ++-
> >  include/linux/kvm_types.h              |  1 +
> >  virt/kvm/kvm_main.c                    |  2 ++
> >  7 files changed, 24 insertions(+), 11 deletions(-)
> >
> > diff --git a/arch/powerpc/include/asm/kvm_book3s.h b/arch/powerpc/include/asm/kvm_book3s.h
> > index caaa0f592d8e..cee4c7f23c8d 100644
> > --- a/arch/powerpc/include/asm/kvm_book3s.h
> > +++ b/arch/powerpc/include/asm/kvm_book3s.h
> > @@ -237,7 +237,8 @@ extern kvm_pfn_t kvmppc_gpa_to_pfn(struct kvm_vcpu *vcpu, gpa_t gpa,
> >                         bool writing, bool *writable);
> >  extern void kvmppc_add_revmap_chain(struct kvm *kvm, struct revmap_entry *rev,
> >                         unsigned long *rmap, long pte_index, int realmode);
> > -extern void kvmppc_update_dirty_map(const struct kvm_memory_slot *memslot,
> > +extern void kvmppc_update_dirty_map(struct kvm *kvm,
> > +                       const struct kvm_memory_slot *memslot,
> >                         unsigned long gfn, unsigned long psize);
> >  extern void kvmppc_invalidate_hpte(struct kvm *kvm, __be64 *hptep,
> >                         unsigned long pte_index);
> > diff --git a/arch/powerpc/kvm/book3s_64_mmu_hv.c b/arch/powerpc/kvm/book3s_64_mmu_hv.c
> > index c63e263312a4..08194aacd2a6 100644
> > --- a/arch/powerpc/kvm/book3s_64_mmu_hv.c
> > +++ b/arch/powerpc/kvm/book3s_64_mmu_hv.c
> > @@ -787,7 +787,7 @@ static void kvmppc_unmap_hpte(struct kvm *kvm, unsigned long i,
> >                 rcbits = be64_to_cpu(hptep[1]) & (HPTE_R_R | HPTE_R_C);
> >                 *rmapp |= rcbits << KVMPPC_RMAP_RC_SHIFT;
> >                 if ((rcbits & HPTE_R_C) && memslot->dirty_bitmap)
> > -                       kvmppc_update_dirty_map(memslot, gfn, psize);
> > +                       kvmppc_update_dirty_map(kvm, memslot, gfn, psize);
> >                 if (rcbits & ~rev[i].guest_rpte) {
> >                         rev[i].guest_rpte = ptel | rcbits;
> >                         note_hpte_modification(kvm, &rev[i]);
> > @@ -1122,8 +1122,10 @@ long kvmppc_hv_get_dirty_log_hpt(struct kvm *kvm,
> >                  * since we always put huge-page HPTEs in the rmap chain
> >                  * corresponding to their page base address.
> >                  */
> > -               if (npages)
> > +               if (npages) {
> >                         set_dirty_bits(map, i, npages);
> > +                       kvm->stat.generic.dirty_pages += npages;
> > +               }
> >                 ++rmapp;
> >         }
> >         preempt_enable();
> > @@ -1178,8 +1180,10 @@ void kvmppc_unpin_guest_page(struct kvm *kvm, void *va, unsigned long gpa,
> >         gfn = gpa >> PAGE_SHIFT;
> >         srcu_idx = srcu_read_lock(&kvm->srcu);
> >         memslot = gfn_to_memslot(kvm, gfn);
> > -       if (memslot && memslot->dirty_bitmap)
> > +       if (memslot && memslot->dirty_bitmap) {
> >                 set_bit_le(gfn - memslot->base_gfn, memslot->dirty_bitmap);
> > +               ++kvm->stat.generic.dirty_pages;
> > +       }
> >         srcu_read_unlock(&kvm->srcu, srcu_idx);
> >  }
> >
> > diff --git a/arch/powerpc/kvm/book3s_64_mmu_radix.c b/arch/powerpc/kvm/book3s_64_mmu_radix.c
> > index b5905ae4377c..dc3fb027020a 100644
> > --- a/arch/powerpc/kvm/book3s_64_mmu_radix.c
> > +++ b/arch/powerpc/kvm/book3s_64_mmu_radix.c
> > @@ -442,7 +442,7 @@ void kvmppc_unmap_pte(struct kvm *kvm, pte_t *pte, unsigned long gpa,
> >         kvmhv_remove_nest_rmap_range(kvm, memslot, gpa, hpa, page_size);
> >
> >         if ((old & _PAGE_DIRTY) && memslot->dirty_bitmap)
> > -               kvmppc_update_dirty_map(memslot, gfn, page_size);
> > +               kvmppc_update_dirty_map(kvm, memslot, gfn, page_size);
> >  }
> >
> >  /*
> > @@ -1150,6 +1150,7 @@ long kvmppc_hv_get_dirty_log_radix(struct kvm *kvm,
> >                 j = i + 1;
> >                 if (npages) {
> >                         set_dirty_bits(map, i, npages);
> > +                       kvm->stat.generic.dirty_pages += npages;
> >                         j = i + npages;
> >                 }
> >         }
> > diff --git a/arch/powerpc/kvm/book3s_hv_rm_mmu.c b/arch/powerpc/kvm/book3s_hv_rm_mmu.c
> > index 632b2545072b..f168ffb0a32b 100644
> > --- a/arch/powerpc/kvm/book3s_hv_rm_mmu.c
> > +++ b/arch/powerpc/kvm/book3s_hv_rm_mmu.c
> > @@ -99,7 +99,8 @@ void kvmppc_add_revmap_chain(struct kvm *kvm, struct revmap_entry *rev,
> >  EXPORT_SYMBOL_GPL(kvmppc_add_revmap_chain);
> >
> >  /* Update the dirty bitmap of a memslot */
> > -void kvmppc_update_dirty_map(const struct kvm_memory_slot *memslot,
> > +void kvmppc_update_dirty_map(struct kvm *kvm,
> > +                            const struct kvm_memory_slot *memslot,
> >                              unsigned long gfn, unsigned long psize)
> >  {
> >         unsigned long npages;
> > @@ -109,6 +110,7 @@ void kvmppc_update_dirty_map(const struct kvm_memory_slot *memslot,
> >         npages = (psize + PAGE_SIZE - 1) / PAGE_SIZE;
> >         gfn -= memslot->base_gfn;
> >         set_dirty_bits_atomic(memslot->dirty_bitmap, gfn, npages);
> > +       kvm->stat.generic.dirty_pages += npages;
> >  }
> >  EXPORT_SYMBOL_GPL(kvmppc_update_dirty_map);
> >
> > @@ -123,7 +125,7 @@ static void kvmppc_set_dirty_from_hpte(struct kvm *kvm,
> >         gfn = hpte_rpn(hpte_gr, psize);
> >         memslot = __gfn_to_memslot(kvm_memslots_raw(kvm), gfn);
> >         if (memslot && memslot->dirty_bitmap)
> > -               kvmppc_update_dirty_map(memslot, gfn, psize);
> > +               kvmppc_update_dirty_map(kvm, memslot, gfn, psize);
> >  }
> >
> >  /* Returns a pointer to the revmap entry for the page mapped by a HPTE */
> > @@ -182,7 +184,7 @@ static void remove_revmap_chain(struct kvm *kvm, long pte_index,
> >         }
> >         *rmap |= rcbits << KVMPPC_RMAP_RC_SHIFT;
> >         if (rcbits & HPTE_R_C)
> > -               kvmppc_update_dirty_map(memslot, gfn,
> > +               kvmppc_update_dirty_map(kvm, memslot, gfn,
> >                                         kvmppc_actual_pgsz(hpte_v, hpte_r));
> >         unlock_rmap(rmap);
> >  }
> > @@ -941,7 +943,7 @@ static long kvmppc_do_h_page_init_zero(struct kvm_vcpu *vcpu,
> >         /* Zero the page */
> >         for (i = 0; i < SZ_4K; i += L1_CACHE_BYTES, pa += L1_CACHE_BYTES)
> >                 dcbz((void *)pa);
> > -       kvmppc_update_dirty_map(memslot, dest >> PAGE_SHIFT, PAGE_SIZE);
> > +       kvmppc_update_dirty_map(kvm, memslot, dest >> PAGE_SHIFT, PAGE_SIZE);
> >
> >  out_unlock:
> >         arch_spin_unlock(&kvm->mmu_lock.rlock.raw_lock);
> > @@ -972,7 +974,8 @@ static long kvmppc_do_h_page_init_copy(struct kvm_vcpu *vcpu,
> >         /* Copy the page */
> >         memcpy((void *)dest_pa, (void *)src_pa, SZ_4K);
> >
> > -       kvmppc_update_dirty_map(dest_memslot, dest >> PAGE_SHIFT, PAGE_SIZE);
> > +       kvmppc_update_dirty_map(kvm, dest_memslot,
> > +                               dest >> PAGE_SHIFT, PAGE_SIZE);
> >
> >  out_unlock:
> >         arch_spin_unlock(&kvm->mmu_lock.rlock.raw_lock);
> > diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
> > index d447b21cdd73..1229a7dd83e3 100644
> > --- a/include/linux/kvm_host.h
> > +++ b/include/linux/kvm_host.h
> > @@ -1444,7 +1444,8 @@ struct _kvm_stats_desc {
> >                 KVM_STATS_BASE_POW10, -9, sz)
> >
> >  #define KVM_GENERIC_VM_STATS()                                                \
> > -       STATS_DESC_COUNTER(VM_GENERIC, remote_tlb_flush)
> > +       STATS_DESC_COUNTER(VM_GENERIC, remote_tlb_flush),                      \
> > +       STATS_DESC_COUNTER(VM_GENERIC, dirty_pages)
> >
> >  #define KVM_GENERIC_VCPU_STATS()                                              \
> >         STATS_DESC_COUNTER(VCPU_GENERIC, halt_successful_poll),                \
> > diff --git a/include/linux/kvm_types.h b/include/linux/kvm_types.h
> > index de7fb5f364d8..ff811bac851a 100644
> > --- a/include/linux/kvm_types.h
> > +++ b/include/linux/kvm_types.h
> > @@ -80,6 +80,7 @@ struct kvm_mmu_memory_cache {
> >
> >  struct kvm_vm_stat_generic {
> >         u64 remote_tlb_flush;
> > +       u64 dirty_pages;
>
> This should read "dirtied_pages", to imply it is the number of pages
> dirtied since start, not the number of pages dirty at a given moment.
Sure, will change it to "dirtied_pages".
>
>
> >  };
> >
> >  struct kvm_vcpu_stat_generic {
> > diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> > index 3e67c93ca403..b99ade3fd2b4 100644
> > --- a/virt/kvm/kvm_main.c
> > +++ b/virt/kvm/kvm_main.c
> > @@ -3084,6 +3084,8 @@ void mark_page_dirty_in_slot(struct kvm *kvm,
> >                                             slot, rel_gfn);
> >                 else
> >                         set_bit_le(rel_gfn, memslot->dirty_bitmap);
> > +
> > +               ++kvm->stat.generic.dirty_pages;
> >         }
> >  }
> >  EXPORT_SYMBOL_GPL(mark_page_dirty_in_slot);
> >
> > base-commit: a3e0b8bd99ab098514bde2434301fa6fde040da2
> > --
> > 2.32.0.605.g8dce9f2422-goog
> >
Thanks,
Jing