[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [PATCH 5/6] migration/postcopy: enable random order target page arri
From: |
Dr. David Alan Gilbert |
Subject: |
Re: [PATCH 5/6] migration/postcopy: enable random order target page arrival |
Date: |
Wed, 6 Nov 2019 20:08:28 +0000 |
User-agent: |
Mutt/1.12.1 (2019-06-15) |
* Wei Yang (address@hidden) wrote:
> After using number of target page received to track one host page, we
> could have the capability to handle random order target page arrival in
> one host page.
>
> This is a preparation for enabling compress during postcopy.
>
> Signed-off-by: Wei Yang <address@hidden>
> ---
> migration/ram.c | 16 +++-------------
> 1 file changed, 3 insertions(+), 13 deletions(-)
>
> diff --git a/migration/ram.c b/migration/ram.c
> index b5759793a9..da0596411c 100644
> --- a/migration/ram.c
> +++ b/migration/ram.c
> @@ -4015,7 +4015,6 @@ static int ram_load_postcopy(QEMUFile *f)
> MigrationIncomingState *mis = migration_incoming_get_current();
> /* Temporary page that is later 'placed' */
> void *postcopy_host_page = mis->postcopy_tmp_page;
> - void *last_host = NULL;
> bool all_zero = false;
> int target_pages = 0;
>
> @@ -4062,24 +4061,15 @@ static int ram_load_postcopy(QEMUFile *f)
> * that's moved into place later.
> * The migration protocol uses, possibly smaller, target-pages
> * however the source ensures it always sends all the components
> - * of a host page in order.
> + * of a host page in one chunk.
> */
> page_buffer = postcopy_host_page +
> ((uintptr_t)host & (block->page_size - 1));
> /* If all TP are zero then we can optimise the place */
> if (target_pages == 1) {
> all_zero = true;
> - } else {
> - /* not the 1st TP within the HP */
> - if (host != (last_host + TARGET_PAGE_SIZE)) {
> - error_report("Non-sequential target page %p/%p",
> - host, last_host);
> - ret = -EINVAL;
> - break;
> - }
I think this is losing more protection than needed.
I think you can still protect against a page from a different host-page
arriving until we've placed the current host-page.
So something like:
if (((uintptr_t)host & ~(block->page_size - 1)) !=
last_host)
and then set last_host to the start of the host page.
Then you'll check if that flush is really working.
Dave
> }
>
> -
> /*
> * If it's the last part of a host page then we place the host
> * page
> @@ -4090,7 +4080,6 @@ static int ram_load_postcopy(QEMUFile *f)
> }
> place_source = postcopy_host_page;
> }
> - last_host = host;
>
> switch (flags & ~RAM_SAVE_FLAG_CONTINUE) {
> case RAM_SAVE_FLAG_ZERO:
> @@ -4143,7 +4132,8 @@ static int ram_load_postcopy(QEMUFile *f)
>
> if (!ret && place_needed) {
> /* This gets called at the last target page in the host page */
> - void *place_dest = host + TARGET_PAGE_SIZE - block->page_size;
> + void *place_dest = (void *)QEMU_ALIGN_DOWN((unsigned long)host,
> + block->page_size);
>
> if (all_zero) {
> ret = postcopy_place_page_zero(mis, place_dest,
> --
> 2.17.1
>
--
Dr. David Alan Gilbert / address@hidden / Manchester, UK
- Re: [PATCH 5/6] migration/postcopy: enable random order target page arrival,
Dr. David Alan Gilbert <=