Il 03/10/2012 19:58, Anand Avati ha scritto: >> >> I think these 3 lines should be removed. We're bypassing the host >> buffer cache just by virtue of using a userspace driver, and that's what >> cache=none cares about. > > O_DIRECT also has an effect on the behavior of the "client side" (the > part within the qemu) of Gluster stack as well. I presume the intention > of O_DIRECT is to minimize use of memory (whether as host' page cache or > buffered data in user space). To that end it is a good idea to leave > O_DIRECT flag set. > > The behavior of whether gluster bricks need to get the O_DIRECT > propagated or not is a different issue. We are exploring the possibility > of not sending O_DIRECT flag over the wire to mimic NFS behavior. That > would be independent of the qemu block driver setting the open flag.
What is the effect of O_DIRECT on the client exactly? Paolo
