On Mon, Oct 23, 2023 at 05:36:07PM -0300, Fabiano Rosas wrote: > Add the direct-io migration parameter that tells the migration code to > use O_DIRECT when opening the migration stream file whenever possible. > > This is currently only used for the secondary channels of fixed-ram > migration, which can guarantee that writes are page aligned.
When you say "secondary channels", I presume you're meaning that the bulk memory regions will be written with O_DIRECT, while general vmstate will use normal I/O on the main channel ? If so, could we explain that a little more directly. Having a mixture of O_DIRECT and non-O_DIRECT I/O on the same file is a little bit of an unusual situation. It will work for us because we're writing to different regions of the file in each case. Still I wonder if it would be sane in the outgoing case to include a fsync() on the file in the main channel, to guarantee that the whole saved file is on-media at completion ? Or perhaps suggest in QAPI that mgmts might consider doing a fsync themselves ? With regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|
