From: "Marek Marczykowski-Górecki" <marmarek@invisiblethingslab.com>
To: "Roger Pau Monné" <roger.pau@citrix.com>
Cc: Ian Jackson <ian.jackson@eu.citrix.com>,
Wei Liu <wei.liu2@citrix.com>,
xen-devel <xen-devel@lists.xen.org>
Subject: Re: libxl - avoid calling block script
Date: Fri, 9 Feb 2018 12:35:13 +0100 [thread overview]
Message-ID: <20180209113513.GK2070@mail-itl> (raw)
In-Reply-To: <20180209110355.jgd3vp24nlwledyt@MacBook-Pro-de-Roger.local>
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On Fri, Feb 09, 2018 at 11:03:55AM +0000, Roger Pau Monné wrote:
> Really adding Ian and Wei.
>
> On Fri, Feb 09, 2018 at 10:55:24AM +0000, Roger Pau Monné wrote:
> > So the problem is creation time for domains that have quite a lot of
> > disks attached. Adding Ian and Wei who know more about the async
> > dispatch system, but I think (at least from a technical PoV) it
> > should be possible to parallelize device attachment and thus hotplug
> > script execution. Devices are independent from each other.
In theory yes, but in practice block script (at least on Linux) takes a
lock and serialize execution...
> > Also the Linux hotplug scripts in general seem extremely convoluted,
> > I'm not sure whether we could gain some speed there just by
> > simplification.
Well, we're comparing a bunch of fork+exec(), including starting bash
(default /bin/sh on most systems), with just a single stat() call...
Handling scripts in libxl itself also takes some time (in my case libxl
live in libvirt, which may or may not have an impact). For a domU with
4 disks, getting rid of hotplug scripts saved about 2s of startup time.
--
Best Regards,
Marek Marczykowski-Górecki
Invisible Things Lab
A: Because it messes up the order in which people normally read text.
Q: Why is top-posting such a bad thing?
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next prev parent reply other threads:[~2018-02-09 11:35 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-02-09 1:02 libxl - avoid calling block script Marek Marczykowski-Górecki
2018-02-09 10:55 ` Roger Pau Monné
2018-02-09 11:03 ` Roger Pau Monné
2018-02-09 11:35 ` Marek Marczykowski-Górecki [this message]
2018-02-23 18:28 ` Wei Liu
2018-02-23 20:14 ` Marek Marczykowski-Górecki
2018-02-26 10:11 ` Roger Pau Monné
2018-02-26 11:58 ` Ian Jackson
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