Re: [Qemu-devel] [PATCH 3/7] arch_init: add ram_madvise_free()

[Lei Li]

On 06/17/2013 12:04 AM, Anthony Liguori wrote:
> Lei Li <address@hidden> writes:
>
> > Signed-off-by: Lei Li <address@hidden>
> > ---
> >   arch_init.c                   |   13 +++++++++++++
> >   include/migration/migration.h |    3 +++
> >   2 files changed, 16 insertions(+), 0 deletions(-)
> >
> > diff --git a/arch_init.c b/arch_init.c
> > index 872020e..fc66bd2 100644
> > --- a/arch_init.c
> > +++ b/arch_init.c
> > @@ -524,6 +524,19 @@ uint64_t ram_bytes_total(void)
> >       return total;
> >   }
> >   
> > +void ram_madvise_free(ram_addr_t size)
> > +{
> > +    void *ram;
> > +    RAMBlock *block = NULL;
> > +
> > +    ram = memory_region_get_ram_ptr(block->mr);
> > +
> > +    /* XXX. Here just simplely madvise(.., MADV_DONTNEED) the whole ram
> > +     * pages, need more work to keep MADV_DONTNEED ram pages that
> > +     * already sent. */
> > +    qemu_madvise(ram, size, MADV_DONTNEED);
> > +}
> > +
> I don't think this is right at all.  There's no guarantee we have a
> single linear mapping of all ram.

Ah, thanks for yourclarification!

> I think you need something a bit more clever than this.

Yes, this need more work.

> >   static void migration_end(void)
> >   {
> >       if (migration_bitmap) {
> > diff --git a/include/migration/migration.h b/include/migration/migration.h
> > index 8866c3c..9cc5285 100644
> > --- a/include/migration/migration.h
> > +++ b/include/migration/migration.h
> > @@ -21,6 +21,7 @@
> >   #include "qapi/error.h"
> >   #include "migration/vmstate.h"
> >   #include "qapi-types.h"
> > +#include "exec/memory.h"
> >   
> >   enum {
> >       MIG_STATE_ERROR,
> > @@ -100,6 +101,8 @@ uint64_t ram_bytes_remaining(void);
> >   uint64_t ram_bytes_transferred(void);
> >   uint64_t ram_bytes_total(void);
> >   
> > +void ram_madvise_free(ram_addr_t size);
> > +
> If you introduce new interfaces, please include documentation in the
> header.

Good to know, thanks!

> Regards,
>
> Anthony Liguori
>
> >   extern SaveVMHandlers savevm_ram_handlers;
> >   
> >   uint64_t dup_mig_bytes_transferred(void);
> > --
> > 1.7.7.6


--
Lei