Re: [Qemu-devel] [PATCH COLO-Frame v11 16/39] ram/COLO: Record the dirty pages that SVM received

[Hailiang Zhang]

On 2015/12/2 3:36, Dr. David Alan Gilbert wrote:
> * zhanghailiang (address@hidden) wrote:
> > We record the address of the dirty pages that received,
> > it will help flushing pages that cached into SVM.
> > We record them by re-using migration dirty bitmap.
> >
> > Signed-off-by: zhanghailiang <address@hidden>
> > ---
> > v11:
> > - Split a new helper function from original
> >    host_from_stream_offset() (Dave's suggestion)
> > - Only do recording work in this patch
> > v10:
> > - New patch split from v9's patch 13
> > - Rebase to master to use 'migration_bitmap_rcu'
> > ---
> >   migration/ram.c | 30 ++++++++++++++++++++++++++++++
> >   1 file changed, 30 insertions(+)
> >
> > diff --git a/migration/ram.c b/migration/ram.c
> > index 9d946a1..da6bbd6 100644
> > --- a/migration/ram.c
> > +++ b/migration/ram.c
> > @@ -2153,6 +2153,7 @@ static inline RAMBlock *ram_block_from_stream(QEMUFile *f,
> >
> >           return block;
> >       }
> > +
> >       len = qemu_get_byte(f);
> >       qemu_get_buffer(f, (uint8_t *)id, len);
> >       id[len] = 0;
>
> That blank should probably go, but other than that:

I will remove it, thanks.

> Reviewed-by: Dr. David Alan Gilbert <address@hidden>
>
> Dave
>
> > @@ -2179,10 +2180,23 @@ static inline void *host_from_ram_block_offset(RAMBlock 
> > *block,
> >   static inline void *colo_cache_from_block_offset(RAMBlock *block,
> >                                                    ram_addr_t offset)
> >   {
> > +    unsigned long *bitmap;
> > +    long k;
> > +
> >       if (!block) {
> >           return NULL;
> >       }
> >
> > +    k = (block->mr->ram_addr + offset) >> TARGET_PAGE_BITS;
> > +    bitmap = atomic_rcu_read(&migration_bitmap_rcu)->bmap;
> > +    /*
> > +    * During colo checkpoint, we need bitmap of these migrated pages.
> > +    * It help us to decide which pages in ram cache should be flushed
> > +    * into VM's RAM later.
> > +    */
> > +    if (!test_and_set_bit(k, bitmap)) {
> > +        migration_dirty_pages++;
> > +    }
> >       return block->colo_cache + offset;
> >   }
> >
> > @@ -2573,6 +2587,7 @@ static int ram_load(QEMUFile *f, void *opaque, int 
> > version_id)
> >   int colo_init_ram_cache(void)
> >   {
> >       RAMBlock *block;
> > +    int64_t ram_cache_pages = last_ram_offset() >> TARGET_PAGE_BITS;
> >
> >       rcu_read_lock();
> >       QLIST_FOREACH_RCU(block, &ram_list.blocks, next) {
> > @@ -2587,6 +2602,15 @@ int colo_init_ram_cache(void)
> >       }
> >       rcu_read_unlock();
> >       ram_cache_enable = true;
> > +    /*
> > +    * Record the dirty pages that sent by PVM, we use this dirty bitmap 
> > together
> > +    * with to decide which page in cache should be flushed into SVM's RAM. Here
> > +    * we use the same name 'migration_bitmap_rcu' as for migration.
> > +    */
> > +    migration_bitmap_rcu = g_new0(struct BitmapRcu, 1);
> > +    migration_bitmap_rcu->bmap = bitmap_new(ram_cache_pages);
> > +    migration_dirty_pages = 0;
> > +
> >       return 0;
> >
> >   out_locked:
> > @@ -2604,9 +2628,15 @@ out_locked:
> >   void colo_release_ram_cache(void)
> >   {
> >       RAMBlock *block;
> > +    struct BitmapRcu *bitmap = migration_bitmap_rcu;
> >
> >       ram_cache_enable = false;
> >
> > +    atomic_rcu_set(&migration_bitmap_rcu, NULL);
> > +    if (bitmap) {
> > +        call_rcu(bitmap, migration_bitmap_free, rcu);
> > +    }
> > +
> >       rcu_read_lock();
> >       QLIST_FOREACH_RCU(block, &ram_list.blocks, next) {
> >           if (block->colo_cache) {
> > --
> > 1.8.3.1
> --
> Dr. David Alan Gilbert / address@hidden / Manchester, UK
>
> .