Re: [PATCH v2 06/15] migration: Yield bitmap_mutex properly when sending/sleeping

[Juan Quintela]

Peter Xu <peterx@redhat.com> wrote:
> On Wed, Oct 12, 2022 at 01:51:07PM -0400, Peter Xu wrote:
>> On Wed, Oct 12, 2022 at 05:43:53PM +0100, Dr. David Alan Gilbert wrote:
>> > * Peter Xu (peterx@redhat.com) wrote:
>> > > Don't take the bitmap mutex when sending pages, or when being throttled 
>> > > by
>> > > migration_rate_limit() (which is a bit tricky to call it here in ram 
>> > > code,
>> > > but seems still helpful).
>> > > 
>> > > It prepares for the possibility of concurrently sending pages in >1 
>> > > threads
>> > > using the function ram_save_host_page() because all threads may need the
>> > > bitmap_mutex to operate on bitmaps, so that either sendmsg() or any kind 
>> > > of
>> > > qemu_sem_wait() blocking for one thread will not block the other from
>> > > progressing.
>> > > 
>> > > Signed-off-by: Peter Xu <peterx@redhat.com>
>> > 
>> > Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
>> > 
>> > although a comment above the reclaration of ram_save_host_pages saying
>> > it can drop the lock would be veyr good.
>> 
>> Let me add that.  Thanks,
>
> A fixup to this patch attached to touch up the comment for
> ram_save_host_page().

Reviewed-by: Juan Quintela <quintela@redhat.com>