ZFS ARC under memory pressure

[Konstantin Belousov]

On Fri, Aug 19, 2016 at 03:38:55PM -0500, Karl Denninger wrote:
> Paging *always* requires one I/O (to write the page(s) to the swap) and
> MAY involve two (to later page it back in.)  It is never a "win" to
> spend a *guaranteed* I/O when you can instead act in a way that *might*
> cause you to (later) need to execute one.
Why would pagedaemon need to write out clean page ?