On 05/30/2012 02:38 PM, Cong Wang wrote: > This is a draft patch of implementing per-file drop caches. > > It introduces a new fcntl command F_DROP_CACHES to drop > file caches of a specific file. The reason is that currently > we only have a system-wide drop caches interface, it could > cause system-wide performance down if we drop all page caches > when we actually want to drop the caches of some huge file. This is useful functionality. Though isn't it already provided with POSIX_FADV_DONTNEED? This functionality was added to GNU dd (8.11) a year ago: http://git.sv.gnu.org/gitweb/?p=coreutils.git;a=commitdiff;h=5f31155 Here are the examples from that patch: # Advise to drop cache for whole file dd if=ifile iflag=nocache count=0 # Ensure drop cache for the whole file dd of=ofile oflag=nocache conv=notrunc,fdatasync count=0 # Drop cache for part of file dd if=ifile iflag=nocache skip=10 count=10 of=/dev/null # Stream data using just the read-ahead cache dd if=ifile of=ofile iflag=nocache oflag=nocache cheers, Pádraig. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>