Re: [Qemu-devel] [RFC PATCH RDMA support v6: 6/7] send pc.ram over RDMA

[Paolo Bonzini]

Il 10/04/2013 06:29, address@hidden ha scritto:
> From: "Michael R. Hines" <address@hidden>
> 
> All that is left for this part of the patch is:
> 
> 1. use the new (optionally defined) save_ram_page function pointer
>    to decide what to do with the page if RDMA is enable or not
>    and return ENOTSUP as agreed.
> 2. invoke hooks from QEMURamControlOps function pointers to hook
>    into the RDMA protocol at the right points in order to perform
>    dynamic page registration.
> Signed-off-by: Michael R. Hines <address@hidden>
> ---
>  arch_init.c |   45 +++++++++++++++++++++++++++++++++++++++++++--
>  1 file changed, 43 insertions(+), 2 deletions(-)
> 
> diff --git a/arch_init.c b/arch_init.c
> index 769ce77..a7d5b16 100644
> --- a/arch_init.c
> +++ b/arch_init.c
> @@ -115,6 +115,7 @@ const uint32_t arch_type = QEMU_ARCH;
>  #define RAM_SAVE_FLAG_EOS      0x10
>  #define RAM_SAVE_FLAG_CONTINUE 0x20
>  #define RAM_SAVE_FLAG_XBZRLE   0x40
> +#define RAM_SAVE_FLAG_REGISTER 0x80 /* perform hook during iteration */

Please rename this to RAM_SAVE_FLAG_HOOK.

>  
>  
>  static struct defconfig_file {
> @@ -170,6 +171,13 @@ static struct {
>      .cache = NULL,
>  };
>  
> +#ifdef CONFIG_RDMA
> +void qemu_ram_registration_start(QEMUFile *f, void *opaque, int section)
> +{
> +    DPRINTF("start section: %d\n", section);
> +    qemu_put_be64(f, RAM_SAVE_FLAG_REGISTER);
> +}
> +#endif

Please put this in migration-rdma.c together with the other QEMUFileOps.

>  int64_t xbzrle_cache_resize(int64_t new_size)
>  {
> @@ -447,15 +455,22 @@ static int ram_save_block(QEMUFile *f, bool last_stage)
>                  ram_bulk_stage = false;
>              }
>          } else {
> +            bool zero;
>              uint8_t *p;
>              int cont = (block == last_sent_block) ?
>                  RAM_SAVE_FLAG_CONTINUE : 0;
>  
>              p = memory_region_get_ram_ptr(mr) + offset;
>  
> +            /* use capability now, defaults to true */
> +            zero = migrate_check_for_zero() ? is_zero_page(p) : false;
> +
>              /* In doubt sent page as normal */
>              bytes_sent = -1;
> -            if (is_zero_page(p)) {
> +            if ((bytes_sent = ram_control_save_page(f, block->offset, 
> +                            offset, cont, TARGET_PAGE_SIZE, zero)) >= 0) {
> +                acct_info.norm_pages++;
> +            } else if (zero) {
>                  acct_info.dup_pages++;
>                  if (!ram_bulk_stage) {
>                      bytes_sent = save_block_hdr(f, block, offset, cont,
> @@ -476,7 +491,7 @@ static int ram_save_block(QEMUFile *f, bool last_stage)
>              }
>  
>              /* XBZRLE overflow or normal page */
> -            if (bytes_sent == -1) {
> +            if (bytes_sent == -1 || bytes_sent == -ENOTSUP) {
>                  bytes_sent = save_block_hdr(f, block, offset, cont, 
> RAM_SAVE_FLAG_PAGE);
>                  qemu_put_buffer_async(f, p, TARGET_PAGE_SIZE);
>                  bytes_sent += TARGET_PAGE_SIZE;
> @@ -598,6 +613,18 @@ static int ram_save_setup(QEMUFile *f, void *opaque)
>      }
>  
>      qemu_mutex_unlock_ramlist();
> +
> +    /*
> +     * These following calls generate reserved messages for future expansion 
> of the RDMA
> +     * protocol. If the ops are not defined, nothing will happen.
> +     *
> +     * Please leave in place. They are intended to be used to pre-register
> +     * memory in the future to mitigate the extremely high cost of dynamic 
> page
> +     * registration.
> +     */
> +    ram_control_before_iterate(f, RAM_CONTROL_SETUP);
> +    ram_control_after_iterate(f, RAM_CONTROL_SETUP);
> +
>      qemu_put_be64(f, RAM_SAVE_FLAG_EOS);
>  
>      return 0;
> @@ -616,6 +643,8 @@ static int ram_save_iterate(QEMUFile *f, void *opaque)
>          reset_ram_globals();
>      }
>  
> +    ram_control_before_iterate(f, RAM_CONTROL_ROUND);
> +
>      t0 = qemu_get_clock_ns(rt_clock);
>      i = 0;
>      while ((ret = qemu_file_rate_limit(f)) == 0) {
> @@ -646,6 +675,12 @@ static int ram_save_iterate(QEMUFile *f, void *opaque)
>  
>      qemu_mutex_unlock_ramlist();
>  
> +    /* 
> +     * must occur before EOS (or any QEMUFile operation) 
> +     * because of RDMA protocol 
> +     */
> +    ram_control_after_iterate(f, RAM_CONTROL_ROUND);
> +
>      if (ret < 0) {
>          bytes_transferred += total_sent;
>          return ret;
> @@ -663,6 +698,8 @@ static int ram_save_complete(QEMUFile *f, void *opaque)
>      qemu_mutex_lock_ramlist();
>      migration_bitmap_sync();
>  
> +    ram_control_before_iterate(f, RAM_CONTROL_FINISH);
> +
>      /* try transferring iterative blocks of memory */
>  
>      /* flush all remaining blocks regardless of rate limiting */
> @@ -676,6 +713,8 @@ static int ram_save_complete(QEMUFile *f, void *opaque)
>          }
>          bytes_transferred += bytes_sent;
>      }
> +
> +    ram_control_after_iterate(f, RAM_CONTROL_FINISH);
>      migration_end();
>  
>      qemu_mutex_unlock_ramlist();
> @@ -864,6 +903,8 @@ static int ram_load(QEMUFile *f, void *opaque, int 
> version_id)
>                  ret = -EINVAL;
>                  goto done;
>              }
> +        } else if (flags & RAM_SAVE_FLAG_REGISTER) {
> +            ram_control_register_iterate(f, RAM_CONTROL_REGISTER); 

Please rename this function to ram_control_load_hook(f, flags).

Paolo

>          }
>          error = qemu_file_get_error(f);
>          if (error) {
>