Messages in this thread | | | From | Al Boldi <> | Subject | Re: [PATCH] Driver Core: devtmpfs - kernel-maintained tmpfs-based /dev | Date | Sat, 8 Aug 2009 00:17:31 +0300 |
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Chris Friesen wrote: > Greg KH wrote: > > On Fri, Aug 07, 2009 at 08:04:08AM +0300, Al Boldi wrote: > >> The question is, how fast can devtmpfs get the device list from the > >> kernel on bootup? How much faster than udev? How much slower than > >> static /dev? > > > > It's much faster than udev, and is equivalent to a static /dev with the > > exception that the group and permission settings that you are used to. > > udev then needs to come along and make those settings, but that's so > > frickin fast it's amazing. > > Earlier in the thread you indicated a 0.5sec speedup over udev. Is that > really considered "much faster"? > > I do agree that it makes sense to do this, but more from an elegance > view than a performance one.
It's definitely more elegant, but at what cost?
For devtmpfs to be a realistic replacement for static /dev, it has to be comparable to static /dev in both speed and size. WRT speed, there should be no slowdown and it should be just as fast as a "tar -xp < dev.tar". WRT size, it should not be dependent on hotplug, and instead offer hotplug as an option.
Thanks!
-- Al
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