On Wed, 21 Mar 2012 12:31:47 +0800 Shaohua Li [off-list ref] wrote:

 But on
the other hand, if user doesn't explictly enable discard, why enable
it? Like fs, we didn't do runtime discard and only run trim occasionally
since discard is slow.

This.  Neither the swapon manpage nor the SWAP_FLAG_DISCARD comment nor
.c code comments nor the 339944663 changelog explain why we do a single
discard at swapon() time and then never again.

It sure *looks* like a bug.  If it isn't then some explanation is sorely
needed.

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  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@kvack.org"> email@kvack.org </a>