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From: Juan Quintela <quintela@redhat.com>
To: qemu-devel@nongnu.org
Cc: "Stefan Hajnoczi" <stefanha@redhat.com>,
	"Dr. David Alan Gilbert" <dgilbert@redhat.com>,
	"Philippe Mathieu-Daudé" <philmd@linaro.org>,
	"Fam Zheng" <fam@euphon.net>,
	"Juan Quintela" <quintela@redhat.com>,
	qemu-block@nongnu.org, "David Hildenbrand" <david@redhat.com>,
	"Peter Xu" <peterx@redhat.com>,
	"Paolo Bonzini" <pbonzini@redhat.com>
Subject: [PULL 5/8] migration: Disallow postcopy preempt to be used with compress
Date: Mon, 21 Nov 2022 13:59:04 +0100	[thread overview]
Message-ID: <20221121125907.62469-6-quintela@redhat.com> (raw)
In-Reply-To: <20221121125907.62469-1-quintela@redhat.com>

From: Peter Xu <peterx@redhat.com>

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.

Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
---
 migration/migration.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/migration/migration.c b/migration/migration.c
index 739bb683f3..f3ed77a7d0 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -1337,6 +1337,17 @@ 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;
-- 
2.38.1



  parent reply	other threads:[~2022-11-21 12:59 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-11-21 12:58 [PULL 0/8] Next patches Juan Quintela
2022-11-21 12:59 ` [PULL 1/8] migration/channel-block: fix return value for qio_channel_block_{readv, writev} Juan Quintela
2022-11-21 12:59 ` [PULL 2/8] migration/multifd/zero-copy: Create helper function for flushing Juan Quintela
2022-11-21 12:59 ` [PULL 3/8] migration: Fix possible infinite loop of ram save process Juan Quintela
2022-11-21 12:59 ` [PULL 4/8] migration: Fix race on qemu_file_shutdown() Juan Quintela
2022-11-21 12:59 ` Juan Quintela [this message]
2022-11-21 12:59 ` [PULL 6/8] migration: Use non-atomic ops for clear log bitmap Juan Quintela
2022-11-21 12:59 ` [PULL 7/8] migration: Disable multifd explicitly with compression Juan Quintela
2022-11-21 12:59 ` [PULL 8/8] migration: Block migration comment or code is wrong Juan Quintela
2022-11-21 15:54 ` [PULL 0/8] Next patches Stefan Hajnoczi

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