From: Zheng Chuan <zhengchuan@huawei.com>
To: "Steve Sistare" <steven.sistare@oracle.com>,
"Qemu Developers" <qemu-devel@nongnu.org>,
"Dr. David Alan Gilbert" <dgilbert@redhat.com>,
"Juan Quintela" <quintela@redhat.com>,
"Daniel P. Berrangé" <berrange@redhat.com>,
"Alex Williamson" <alex.williamson@redhat.com>,
"Paolo Bonzini" <pbonzini@redhat.com>,
"Philippe Mathieu-Daudé" <philmd@redhat.com>,
Xiexiangyou <xiexiangyou@huawei.com>
Subject: Re: [PATCH V5 00/25] Live Update [restart] : fork mode?
Date: Wed, 4 Aug 2021 17:30:05 +0800 [thread overview]
Message-ID: <efd2ef7f-b65b-3551-b581-b25050fbb2ab@huawei.com> (raw)
In-Reply-To: <ad3f7ebe-8086-d70c-8db7-997e8a5fa411@huawei.com>
kindly ping?
On 2021/7/30 21:10, Zheng Chuan wrote:
> Hi, Steve
> I have saw the discussion about the fork+exec mode below:
> https://www.mail-archive.com/qemu-devel@nongnu.org/msg815956.html
>
> And I am still very curious and I want to discuss about the possibility to support both fork+exec and exec in cpr framework.
>
> 1.Why
> fork+exec could have some advantages and also drawbacks versus execvp() directly.
> Advantages
> i) fork+exec give the chance to fallback to original process even after we do exec which is important for workload seamless if any error happens.
> ii) smaller downtime since we could remove the vm_start() downtime out of the frozen window.
> Drawbacks
> i)need more codes to handle including fork,address/ports conflict between parent and child.
> ii)more complex life cycle management for the two processes.
>
> 2.How
> The cpr framework is flexible and scalable, and maybe we can make use of most codes to support both execvp and fork+exec mode.
> However, we may need to do more work compared to execvp method.
> i) do fork mode in a thread like migration thread
> ii) make parent and child talk to each other through socket or anonymous pipe
> iii)make use of sharing mechanism of fds in cpr framework including memfd, vfio and devices fds
> iv)deal with the conflict about the socket address and port like vnc (do by reuse port and pass the different args by cprexec)
> v) do life cycle managements for two qemu processes and need parent exit and reconnection for the child at last by the management service
>
> Please tell me if I am missing something important:)
>
--
Regards.
Chuan
next prev parent reply other threads:[~2021-08-04 9:31 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-30 13:10 [PATCH V5 00/25] Live Update [restart] : fork mode? Zheng Chuan
2021-08-04 9:30 ` Zheng Chuan [this message]
2021-08-04 20:50 ` Steven Sistare
2021-08-05 14:04 ` Zheng Chuan
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