On Fri, Jan 23, 2009 at 12:04:33AM +0000, Daniel J Blueman wrote: > In order to maximise user experience thus performance, we need to > ensure the disk partitions created on SSDs/USB flash drives/RAID > arrays are 4KB (perhaps up to 128KB) aligned. There are considerable > benefits with the flash/RAID controller opening half as many > pages/stripes on small reads. This pays better with slower SSDs in eg > netbooks. > > Patches have entered the upstream kernel to detect when drives are > solid-state [1], though the dust hasn't settled on the interface. > > How acceptable would getting the userspace partitioner changes into > Jaunty if proven to be stable and robust?
This seems like something that could be added as a libparted constraint without *too* much pain. If and only if the corresponding kernel changes go into the Ubuntu kernel (work with kernel-t...@lists.ubuntu.com, I think), I agree that we should change the partitioner too, and pass the changes to parted upstream, although I would add that the changes need to be reasonably simple and elegant as well as stable and robust; I only like partitioner code that I can understand. :-) The simplest way to do this appears to be: * change libparted/arch/linux.c to detect physical sector size based on information exposed by the kernel (physical sector size is a slightly odd term here, but it seems to produce the alignment results you're asking for) * ensure that this actually works properly in parted, noting that this feature is currently marked as experimental (see the ped_device_get_constraint function) * change parted_server in partman-base to use device constraints, since it doesn't currently * possibly change other libparted clients such as gparted and qtparted to use device constraints if they don't already (I haven't checked) Do you know whether the kernel is likely to tell us the desired alignment? It seems a little strange to infer an alignment simply from the fact that the disk is non-rotational, and in your post you yourself don't seem entirely sure of the desired size. I imagine it will vary from device to device. Are you willing to do this work? If you'd like to work with me or other installer developers on IRC, #ubuntu-installer is open. Thanks, -- Colin Watson [cjwat...@ubuntu.com] -- Ubuntu-devel-discuss mailing list Ubuntu-devel-discuss@lists.ubuntu.com Modify settings or unsubscribe at: https://lists.ubuntu.com/mailman/listinfo/ubuntu-devel-discuss