On 27/06/11 06:38, KOSAKI Motohiro wrote: >> Hmm, What if you do want to evict it from the cache for testing purposes? >> Perhaps this functionality should be associated with POSIX_FADV_NOREUSE? >> dd has been recently modified to support invalidating the cache for a file, >> and it uses POSIX_FADV_DONTNEED for that. >> http://git.sv.gnu.org/gitweb/?p=coreutils.git;a=commitdiff;h=5f311553 > > This change don't break dd. dd don't have a special privilege of file cache > dropping if it's also used by other processes. > > if you want to drop a cache forcely (maybe for testing), you need to use > /proc/sys/vm/drop_caches. It's ok to ignore other processes activity because > it's privilege operation. Well the function and privileges are separate things. I think we've agreed that the new functionality is best associated with POSIX_FADV_NOREUSE, and the existing functionality with POSIX_FADV_DONTNEED. BTW, I don't think privileges are currently enforced as I got root to cache a file here with: # (time md5sum; sleep 100) < big.file And a normal user was able to uncache with: $ dd iflag=nocache if=big.file count=0 Anyway as said, this is a separate "issue". 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>