On Thu, Sep 26, 2013 at 11:14:01AM -0500, Seth Jennings wrote: > > I can see this burning out your SSD as well. If someone enabled this on > a machine that did large (relative to the size of the SDD) streaming > reads, you'd be writing to the SSD continuously and never have a cache > hit. If we are to do page-level caching, we really need to change the VM to use something like IBM's Adaptive Replacement Cache[1], which allows us to track which pages have been more frequently used, so that we only cache those pages, as opposed to those that land in the cache once and then aren't used again. (Consider what might happen if you are using clean cache and then the user does a full backup of the system.) [1] http://en.wikipedia.org/wiki/Adaptive_replacement_cache This is how ZFS does SSD caching; the basic idea is to only consider for cacheing those pages which have been promoted into its Frequenly Refrenced list, and then have been subsequently aged out. At that point, the benefit we would have over a dm-cache solution is that we would be taking advantage of the usage information tracked by the VM to better decide what is cached on the SSD. So something to think about, - Ted -- 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/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>