On Fri, 24 Jul 2015 11:11:22 AM Duncan wrote: > The option is mem=nn[KMG]. You may also need memmap=, presumably > memmap=nn[KMG]$ss[KMG], to reserve the unused memory area, preventing its > use for PCI address space, since that would collide with the physical > memory that's there but unused due to mem=. > > That should let you test with mem=2G, so double-memory becomes 4G. =:^) That's a good thing to note. > Meanwhile, does bonnie do pre-allocation for its tests? http://www.coker.com.au/bonnie++/readme.html No. The above URL gives details on the tests. > > What I did see from years ago seemed to be that you'd have to disable > > COW where you knew there would be large files. I'm really hoping > > there's a way to avoid this type of locking, because I don't think I'd > > be comfortable knowing a non-root user could bomb the system with a > > large file in the wrong area. > > The problem with cow isn't large files in general, it's rewrites into the > middle of them (as opposed to append-writes). If the writes are > sequential appends, or if it's write-one-read-many, cow on large files > doesn't tend to be an issue. The Bonnie++ rewrite test might be a pathological case for BTRFS. But it's a test that other filesystems have handled for decades. -- My Main Blog http://etbe.coker.com.au/ My Documents Blog http://doc.coker.com.au/ -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
