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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