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[4/5] migration: Disallow postcopy preempt to be used with compress

Message ID 20220920223800.47467-5-peterx@redhat.com
State New
Headers show
Series migration: Bug fixes (prepare for preempt-full) | expand

Commit Message

Peter Xu Sept. 20, 2022, 10:37 p.m. UTC 
The preempt mode requires the capability to assign channel for each of the
page, while the compression logic will currently assign pages to different
compress thread/local-channel so potentially they're incompatible.

Signed-off-by: Peter Xu <peterx@redhat.com>
---
 migration/migration.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

Comments

Dr. David Alan Gilbert Sept. 22, 2022, 4:29 p.m. UTC | #1 
* Peter Xu (peterx@redhat.com) wrote:
> The preempt mode requires the capability to assign channel for each of the
> page, while the compression logic will currently assign pages to different
> compress thread/local-channel so potentially they're incompatible.
> 
> Signed-off-by: Peter Xu <peterx@redhat.com>

Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

> ---
>  migration/migration.c | 11 +++++++++++
>  1 file changed, 11 insertions(+)
> 
> diff --git a/migration/migration.c b/migration/migration.c
> index fb4066dfb4..07c74a79a2 100644
> --- a/migration/migration.c
> +++ b/migration/migration.c
> @@ -1341,6 +1341,17 @@ static bool migrate_caps_check(bool *cap_list,
>              error_setg(errp, "Postcopy preempt requires postcopy-ram");
>              return false;
>          }
> +
> +        /*
> +         * Preempt mode requires urgent pages to be sent in separate
> +         * channel, OTOH compression logic will disorder all pages into
> +         * different compression channels, which is not compatible with the
> +         * preempt assumptions on channel assignments.
> +         */
> +        if (cap_list[MIGRATION_CAPABILITY_COMPRESS]) {
> +            error_setg(errp, "Postcopy preempt not compatible with compress");
> +            return false;
> +        }
>      }
>  
>      return true;
> -- 
> 2.32.0
>
diff mbox series

Patch

diff --git a/migration/migration.c b/migration/migration.c
index fb4066dfb4..07c74a79a2 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -1341,6 +1341,17 @@  static bool migrate_caps_check(bool *cap_list,
             error_setg(errp, "Postcopy preempt requires postcopy-ram");
             return false;
         }
+
+        /*
+         * Preempt mode requires urgent pages to be sent in separate
+         * channel, OTOH compression logic will disorder all pages into
+         * different compression channels, which is not compatible with the
+         * preempt assumptions on channel assignments.
+         */
+        if (cap_list[MIGRATION_CAPABILITY_COMPRESS]) {
+            error_setg(errp, "Postcopy preempt not compatible with compress");
+            return false;
+        }
     }
 
     return true;