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From: Peter Xu <peterx@redhat.com>
To: Joao Martins <joao.m.martins@oracle.com>
Cc: qemu-devel@nongnu.org, Juan Quintela <quintela@redhat.com>,
	Leonardo Bras <leobras@redhat.com>,
	Eric Blake <eblake@redhat.com>,
	Markus Armbruster <armbru@redhat.com>,
	Avihai Horon <avihaih@nvidia.com>,
	Yishai Hadas <yishaih@nvidia.com>,
	"Maciej S. Szmigiero" <maciej.szmigiero@oracle.com>
Subject: Re: [PATCH 0/5] migration: Downtime observability improvements
Date: Wed, 4 Oct 2023 13:19:20 -0400	[thread overview]
Message-ID: <ZR2emE8jdcYRLVUr@x1n> (raw)
In-Reply-To: <20230926161841.98464-1-joao.m.martins@oracle.com>

On Tue, Sep 26, 2023 at 05:18:36PM +0100, Joao Martins wrote:
> For now, mainly precopy data, and here I added both tracepoints and
> QMP stats via query-migrate. Postcopy is still missing.

IIUC many of those will cover postcopy too, but not all?

I think the problem is postcopy didn't update downtime_start, however it
updates MigrationState.downtime, and probably we can start to keep it more
like precopy, e.g., in postcopy_start(), where downtime_start can be
time_at_stop (or it can be more accurate; now it's probably fetching the
timestamp too early).

Basically if we want to expose anything, especially some qapi object, IMHO
we'd better make it work for both pre/post copy because otherwise it'll be
hard for mgmt app to know which qemu supports precopy only, and which
support both (if we'll add that for postcopy too).

Thanks,

-- 
Peter Xu



  parent reply	other threads:[~2023-10-04 17:20 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-09-26 16:18 [PATCH 0/5] migration: Downtime observability improvements Joao Martins
2023-09-26 16:18 ` [PATCH 1/5] migration: Store downtime timestamps in an array Joao Martins
2023-09-28  1:55   ` Wang, Lei
2023-09-28 13:31     ` Joao Martins
2023-09-26 16:18 ` [PATCH 2/5] migration: Collect more timestamps during switchover Joao Martins
2023-09-26 16:18 ` [PATCH 3/5] migration: Add a tracepoint for the downtime stats Joao Martins
2023-09-26 16:18 ` [PATCH 4/5] migration: Provide QMP access to " Joao Martins
2023-10-04 17:10   ` Peter Xu
2023-10-06 11:37     ` Joao Martins
2023-10-06 14:27       ` Peter Xu
2023-09-26 16:18 ` [PATCH 5/5] migration: Print expected-downtime on completion Joao Martins
2023-10-04 19:33   ` Peter Xu
2023-10-06 11:45     ` Joao Martins
2023-10-31 13:14   ` Juan Quintela
2023-11-02 10:22     ` Joao Martins
2023-10-04 17:19 ` Peter Xu [this message]
2023-10-06 11:39   ` [PATCH 0/5] migration: Downtime observability improvements Joao Martins

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