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Re: [MirageOS-devel] Domain creation/boot times and Xen toolstack

Hi Anil,

anil@xxxxxxxxxx said:
> There were a sequence of slow bits in xl that we progressively fixed.
> Most of these should be winding their way upstream as they get cleaned up.
> Improvements came from:
> 1) Replace hotplug script with minimal version (currently a shell script)
> 2) Replace hotplug script with inline ioctl() gave even better results 
>    as no forking happened at all.
> 3) Parallelise hotplug with domain build.
> 4) Don't block on primary console
> 5) Use Dave's XenStore+Irmin with reduced transaction conflicts.
> Number 3) is fairly invasive to libxl, and the XenstoreNG is still being
> prepared for release, but the minimal ioctl is pretty easy and could be the
> default.

Right, 1) and 2) matches what we found with Ian J. while quickly looking at
low-hanging fruit to optimize at the hack day after the conference.

Is there a version of xen.git with these patches that I can build and use
to test? I'd like to try spinning up large numbers of rump kernel based
domUs which is impractical with current domain creation times.

One thing not on your list is qemu spinup time; I presume this is because
you are not using blkfront? The default backend for blkfront is qtap which
unfortunately relies on qemu; vanilla Linux dom0 kernels don't appear to
support any other backends (eg. blktap).

> We're preparing a camera-ready paper on this for NSDI 2015, so I'll share
> that with you privately and the camera-ready with the list (if anyone wants
> to read it, please ask -- I just don't want the draft version to be 
> archived by crawlers and so am not posting it here).

Yes, please.


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