At Tue, 30 Oct 2012 18:30:37 +0800, Liu Yuan wrote: > > On 10/30/2012 08:49 AM, MORITA Kazutaka wrote: > > At Thu, 25 Oct 2012 13:52:01 +0900, > > MORITA Kazutaka wrote: > >> > >> To make sure that data is not cached by the host os, we cannot drop > >> O_DSYNC when O_DIRECT is not set. > >> > > Why data are cached in page cache a problem? We do sync(2) it afterwards.
For users who run VMs on storage nodes, more memory should be used for guest OSes. It's inefficient to cache data in both host and guest page caches. > > We don't set O_DIRECT for inode object, so sync(2) won't flush it to > disk safely? O_DIRECT imposes alignment restrictions on both the file offset and the buffer length, so we cannot use it for any files other than data objects. Thanks, Kazutaka -- sheepdog mailing list [email protected] http://lists.wpkg.org/mailman/listinfo/sheepdog
