while attic is running, file system access is slowed down for the rest of the system. that can be expected, but its effects could be mitigated if attic used posix_fadvise(POSIX_FADV_DONTNEED) on the files it is backuping. this tells the operating tystem that the "data will not be accessed in the near future" (man 2 posix_fadvise).

this should minimize the amount of disk cache contents dropped from ram to accomodate attic's reads, while not slowing down attic. (it won't read over the same file itself (will it?), but the kernel can't know that without being told, and might keep the files around just in case attic wants to look at them again).