From: Peter Xu <peterx@redhat.com>
To: "Wang, Wei W" <wei.w.wang@intel.com>
Cc: "Wang, Lei4" <lei4.wang@intel.com>,
"qemu-devel@nongnu.org" <qemu-devel@nongnu.org>,
"farosas@suse.de" <farosas@suse.de>
Subject: Re: [PATCH] migration: Yield coroutine when receiving MIG_CMD_POSTCOPY_LISTEN
Date: Tue, 2 Apr 2024 17:43:48 -0400 [thread overview]
Message-ID: <Zgx8FFzaFS1RsNmc@x1n> (raw)
In-Reply-To: <DS0PR11MB6373B342B3CFF787E3C2A5FFDC3E2@DS0PR11MB6373.namprd11.prod.outlook.com>
On Tue, Apr 02, 2024 at 07:20:01AM +0000, Wang, Wei W wrote:
> > IIUC we still need that pre_7_2 stuff and keep the postponed connect() to
> > make sure the ordering is done properly. Wei, could you elaborate the patch
> > you mentioned? Maybe I missed some spots.
>
> Sure. I saw your patch (5655aab079) ensures that the preempt channel to be
> created when PONG is received from the destination, which indicates that
> the main channel has been ready on the destination side.
>
> Why was it decided to postpone the preempt channel's connect() for newer QEMU
> only? The old QEMU (before 7.2) still performs preempt channel connect() in
> migrate_fd_connect(), doesn't it have the disordering issue?
Yes it has, but the solution actually was not compatible with older
binaries, so migration was broken back then.. See:
https://lore.kernel.org/qemu-devel/20230326172540.2571110-1-peterx@redhat.com/
My memory was that we didn't have a good solution to fix it without
breaking the old protocol, so it can only be fixed on newer binaries.
Thanks,
--
Peter Xu
prev parent reply other threads:[~2024-04-02 21:44 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-03-29 3:32 [PATCH] migration: Yield coroutine when receiving MIG_CMD_POSTCOPY_LISTEN Lei Wang
2024-03-29 8:54 ` Wang, Wei W
2024-04-01 16:13 ` Peter Xu
2024-04-01 17:17 ` Fabiano Rosas
2024-04-01 18:47 ` Peter Xu
2024-04-01 21:22 ` Fabiano Rosas
2024-04-02 6:55 ` Wang, Lei
2024-04-02 7:25 ` Wang, Wei W
2024-04-02 9:28 ` Wang, Lei
2024-04-02 21:39 ` Peter Xu
2024-04-03 8:35 ` Wang, Lei
2024-04-03 14:42 ` Peter Xu
2024-04-03 16:04 ` Wang, Wei W
2024-04-03 16:33 ` Peter Xu
2024-04-04 10:11 ` Wang, Wei W
2024-04-02 7:20 ` Wang, Wei W
2024-04-02 21:43 ` Peter Xu [this message]
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