Re: [Qemu-devel] [PATCH v2 3/3] migration: add bitmap for received page

[Alexey Perevalov]

On 06/16/2017 12:06 PM, Peter Xu wrote:
> On Thu, Jun 15, 2017 at 07:36:15PM +0300, Alexey Perevalov wrote:
>
> [...]
>
> > +void init_receivedmap(void)
> > +{
> > +    RAMBlock *rb;
> > +
> > +    RAMBLOCK_FOREACH(rb) {
> > +        unsigned long pages;
> > +        pages = rb->max_length >> TARGET_PAGE_BITS;
> Nit: I would assert(!rb->receivedmap) before new it in case for leak.
ok,
> > +        rb->receivedmap = bitmap_new(pages);
> > +    }
> > +}
> > +
> > +static unsigned long int get_received_bit_offset(void *host_addr, RAMBlock *rb)
> > +{
> > +    uint64_t host_addr_offset = (uint64_t)(uintptr_t)(host_addr
> > +                                                      - (void *)rb->host);
> > +    return host_addr_offset >> TARGET_PAGE_BITS;
> > +}
> Can we rename this function to ramblock_get_pfn() and export it in
> ramblock API (exec/ram_addr.h)?
if you need it, I'll place export into ram_addr.h
but name, PFN could confuse, because in case of hugepage
address this function will not return real PFN, due to

TARGET_PAGE_BITS usage.

> static inline uint64_t ramblock_get_pfn(RAMBlock *rb, void *host)
> {
>      return (host - rb->host) >> TARGET_PAGE_BITS;
> }
>
> > +
> > +int test_receivedmap_by_addr(void *host_addr, RAMBlock *rb)
> > +{
> > +    return test_bit(get_received_bit_offset(host_addr, rb), rb->receivedmap);
> > +}
> > +
> > +void set_receivedmap_by_addr(void *host_addr, RAMBlock *rb)
> > +{
> > +    set_bit_atomic(get_received_bit_offset(host_addr, rb), rb->receivedmap);
> > +}
> > +
> >   /*
> >    * An outstanding page request, on the source, having been received
> >    * and queued
> > @@ -2324,8 +2352,13 @@ static int ram_load_setup(QEMUFile *f, void *opaque)
> >   
> >   static int ram_load_cleanup(void *opaque)
> >   {
> > +    RAMBlock *rb;
> >       xbzrle_load_cleanup();
> >       compress_threads_load_cleanup();
> > +
> > +    RAMBLOCK_FOREACH(rb) {
> Nit: I'd prefer: if (rb->receivedmap) {...}
g_free already contains it
> > +        g_free(rb->receivedmap);
> and: rb->receivedmap = NULL later.
why not )
> > +    }
> >       return 0;
> >   }
> >   
> > diff --git a/migration/ram.h b/migration/ram.h
> > index c081fde..7048ff9 100644
> > --- a/migration/ram.h
> > +++ b/migration/ram.h
> > @@ -52,4 +52,9 @@ int ram_discard_range(const char *block_name, uint64_t start, 
> > size_t length);
> >   int ram_postcopy_incoming_init(MigrationIncomingState *mis);
> >   
> >   void ram_handle_compressed(void *host, uint8_t ch, uint64_t size);
> > +
> > +void init_receivedmap(void);
> > +int test_receivedmap_by_addr(void *host_addr, RAMBlock *rb);
> > +void set_receivedmap_by_addr(void *host_addr, RAMBlock *rb);
> Nit: I would name these names as: ramblock_recv_map_*().
>
> > +
> >   #endif
> > diff --git a/migration/savevm.c b/migration/savevm.c
> > index 31158da..668d3bb 100644
> > --- a/migration/savevm.c
> > +++ b/migration/savevm.c
> > @@ -1372,6 +1372,7 @@ static int 
> > loadvm_postcopy_handle_advise(MigrationIncomingState *mis)
> >           return -1;
> >       }
> >   
> > +    init_receivedmap();
> >       remote_pagesize_summary = qemu_get_be64(mis->from_src_file);
> >       local_pagesize_summary = ram_pagesize_summary();
> >   
> > --
> > 1.9.1
> Again, did you trap precopy?
sorry, I really forgot, now it's not copied bitmap, it's
received bitmap. So, I know about
case RAM_SAVE_FLAG_PAGE, but it seems another cases exist 
(compressed/xbzrle)
and there is no single point where coping is doing.


> Thanks,

--
Best regards,
Alexey Perevalov