On Tue, Jul 19, 2011 at 10:20:35PM -0600, Eric Blake wrote: > O_DIRECT has stringent requirements. Rather than make lots of changes > at each site that wants to use O_DIRECT, it is easier to offload > the work through a helper process that mirrors the I/O between a > pipe and the actual direct fd, so that the other end of the pipe > no longer has to worry about constraints. > > Plus, if the kernel ever gains better posix_fadvise support, then we > only have to touch a single file to let all callers benefit from a > more efficient way to avoid file system caching. > > * src/util/virfile.h (virFileDirectFdFlag, virFileDirectFdNew) > (virFileDirectFdClose, virFileDirectFdFree): New prototypes. > * src/util/virdirect.c: Implement new wrapper object. > * src/libvirt_private.syms (virfile.h): Export new symbols. > * cfg.mk (useless_free_options): Add to list. > * po/POTFILES.in: Add new translations. > --- > > v2: move everything into virfile.c rather than creating a new file, > with renames everywhere. Fail rather than silently ignore systems > where O_DIRECT is 0. Add comments to take advantage of posix_fadvise > rather than O_DIRECT if the Linux kernel ever gets fixed. Add > virFileDirectFdFlag as a better probe of which cache-bypass mechanism > is actually being used. Better documentation. > > cfg.mk | 1 + > po/POTFILES.in | 1 + > src/libvirt_private.syms | 4 + > src/util/virfile.c | 175 +++++++++++++++++++++++++++++++++++++++++++++- > src/util/virfile.h | 15 ++++ > 5 files changed, 195 insertions(+), 1 deletions(-) ACK Daniel -- |: http://berrange.com -o- http://www.flickr.com/photos/dberrange/ :| |: http://libvirt.org -o- http://virt-manager.org :| |: http://autobuild.org -o- http://search.cpan.org/~danberr/ :| |: http://entangle-photo.org -o- http://live.gnome.org/gtk-vnc :| -- libvir-list mailing list libvir-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/libvir-list