Re: [RFC PATCH 0/5] migration: fast snapshot load

[Peter Xu <peterx@redhat.com>]

On Fri, Jun 19, 2026 at 06:48:57PM +0530, Aadeshveer Singh wrote:
> From 70ab2949ef99968c2fc16e6a0d9860a993514367 Mon Sep 17 00:00:00 2001
> From: Aadeshveer Singh <aadeshveer07@gmail.com>
> Date: Fri, 19 Jun 2026 18:12:36 +0530
> Subject: [PATCH] migration: postcopy-blocktime support for fast snapshot load
> 
> Add postcopy-blocktime support to fast snapshot load by calling
> mark_postcopy_blocktime_begin(), on all page faults intercepted by fault
> thread.
> 
> There is no need to call mark_postcopy_blocktime_end(), as
> postcopy_mapped_ram_load_page() calls postcopy_place_page() and
> postcopy_place_page_zero() which call the end marking internally.
> 
> Signed-off-by: Aadeshveer Singh <aadeshveer07@gmail.com>
> ---
>  migration/postcopy-ram.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/migration/postcopy-ram.c b/migration/postcopy-ram.c
> index 0ee294a381..2f4698fbed 100644
> --- a/migration/postcopy-ram.c
> +++ b/migration/postcopy-ram.c
> @@ -1436,6 +1436,12 @@ static void *postcopy_ram_fault_thread(void *opaque)
>                                                  msg.arg.pagefault.feat.ptid);
>  
>              if (migrate_fast_snapshot_load()) {
> +                WITH_QEMU_LOCK_GUARD(&mis->page_request_mutex)
> +                {
> +                    mark_postcopy_blocktime_begin(msg.arg.pagefault.address,
> +                                                  msg.arg.pagefault.feat.ptid,
> +                                                  rb);
> +                }
>                  if (postcopy_mapped_ram_load_page(
>                          mis, rb, rb_offset, msg.arg.pagefault.address, 1)) {
>                      break;

Let's squash this directly to your core patch 4, then mention it in the
commit log.

Even if I left quite some comments, most of them are small nitpicks. It's
good to know there're only a few postcopy functions need some touch, and
most logics can be reused.

The RFC series looks a great start, thank you!

-- 
Peter Xu