Messages in this thread | | | Date | Mon, 27 Jun 2011 18:44:51 +0900 | From | KOSAKI Motohiro <> | Subject | Re: [PATCH RFC] fadvise: move active pages to inactive list with POSIX_FADV_DONTNEED |
| |
(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 from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |