On Thu, Dec 8, 2011 at 12:38 PM, Riccardo Murri <riccardo.mu...@gmail.com> wrote: > Hi *, > > the file-backed `ubd` devices in my UML instances are terribly slow, > and generate a lot of "iowait" load on the host. It looks like as if > filesystems mounted from `ubd` devices were using the `sync` option. > > This happens with kernels downloaded from uml.devloop.org.uk, as well > with kernels that I compiled myself (but using basically the same > config as the devloop ones); I tried 2.6.38.x and 2.6.39.x (for some > random values of "x"). > > This does *not* happen with Debian/Ubuntu's kernel 2.6.32.5, which > unfortunately exhibit a filesystem corruption bug. > > The host is in any case Ubuntu "natty", running 2.6.39-3-generic. > > Is this expected?
Not really ;) The ubd got only a few patches since 2.6.32, bisecting should be an easy task. Commit 4752690 fixes the data corruption issue. [rw@inhelltoy tip]$ git log --oneline v2.6.32.. arch/um/drivers/ubd_* 8535639 um: fix ubd cow size c506c0e um: take ubd_user.h to its users... 0a9e70b um: kill shared/mem_kern.h dbddc51 um: don't include kern.h unless it's needed 078073a um: -include user.h for USER_OBJ, trim includes 22e6500 um: Replace deprecated spinlock initialization 5704e44 Merge branch 'config' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/bkl 9a181c5 uml: kill big kernel lock 4752690 ubd: fix incorrect sector handling during request restart 6e9624b block: push down BKL into .open and .release 5a0e3ad include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 8a78362 block: Consolidate phys_segment and hw_segment limits 086fa5f block: Rename blk_queue_max_sectors to blk_queue_max_hw_sectors 6613c5e uml: convert to seq_file/proc_fops -- Thanks, //richard ------------------------------------------------------------------------------ Cloud Services Checklist: Pricing and Packaging Optimization This white paper is intended to serve as a reference, checklist and point of discussion for anyone considering optimizing the pricing and packaging model of a cloud services business. Read Now! http://www.accelacomm.com/jaw/sfnl/114/51491232/ _______________________________________________ User-mode-linux-user mailing list User-mode-linux-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/user-mode-linux-user
