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From: David Edmondson <dme@sun.com>
To: xen-devel@lists.xensource.com
Subject: Re: [PATCH] Require that xenstored writes to a domain complete in a single chunk
Date: Mon, 26 Feb 2007 17:48:25 +0000	[thread overview]
Message-ID: <87slcsx11y.fsf@apfelstrudel.hh.sledj.net> (raw)
In-Reply-To: C208C762.A2B6%keir@xensource.com

* keir@xensource.com [2007-02-26 17:20:34]
> This seems dubious. There's no reason we might not have payloads
> bigger than the ring size (which is only 1kB).

Agreed.

> The right fix would be in the guest, which should already be
> stopping any transactions or commands across save/restore. Does this
> problem occur when xenstored sends an asynchronous watch-fired
> message?

All of the cases I examined (a few dozen) were for watch events.

> Probably the packet-reading thread should be interrupted
> and put to sleep before suspending.

I'll look at this.

> For older guest compatibility perhaps we can take a variant of your
> patch that only waits for enough space is the entire message fits in
> the ring in one go. This would be 'best-effort' at compatibility
> while not precluding use of larger messages in general.

Is the implication that you think that this problem could occur with a
Linux guest (I've never seen it, though have tested much less)?

dme.
-- 
David Edmondson, Sun Microsystems, http://www.dme.org

  reply	other threads:[~2007-02-26 17:48 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-02-26 16:24 [PATCH] Require that xenstored writes to a domain complete in a single chunk David Edmondson
2007-02-26 17:20 ` Keir Fraser
2007-02-26 17:48   ` David Edmondson [this message]
2007-02-26 18:14     ` Keir Fraser
2007-02-26 19:09       ` John Levon
2007-02-26 23:12         ` Keir Fraser

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