(2011/06/27 18:17), Pádraig Brady wrote: > 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". I'm failed to see your point. Why does dd need to ignore other process activity? If no other process, this patch doesn't change any behavior. Isn't it? -- 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>