Hi Kame, On Wed, Mar 27, 2013 at 02:15:41PM +0900, Kamezawa Hiroyuki wrote: > (2013/03/27 11:22), Minchan Kim wrote: > > Swap subsystem does lazy swap slot free with expecting the page > > would be swapped out again so we can't avoid unnecessary write. > > > > But the problem in in-memory swap is that it consumes memory space > > until vm_swap_full(ie, used half of all of swap device) condition > > meet. It could be bad if we use multiple swap device, small in-memory swap > > and big storage swap or in-memory swap alone. > > > > This patch changes vm_swap_full logic slightly so it could free > > swap slot early if the backed device is really fast. > > For it, I used SWP_SOLIDSTATE but It might be controversial. > > So let's add Ccing Shaohua and Hugh. > > If it's a problem for SSD, I'd like to create new type SWP_INMEMORY > > or something for z* family. > > > > Other problem is zram is block device so that it can set SWP_INMEMORY > > or SWP_SOLIDSTATE easily(ie, actually, zram is already done) but > > I have no idea to use it for frontswap. > > > > Any idea? > > > Another thinking....in what case, in what system configuration, > vm_swap_full() should return false and delay swp_entry freeing ? It's a really good question I had have in mind from long time ago. If I catch your point properly, your question is "Couldn't we remove vm_swap_full logic?" If so, the answer is "I have no idea and would like to ask it to Hugh". Academically, it does make sense swap-out page is unlikely to be working set so it could be swap out again and I believe it was merged since we had the workload could be enhanced by the logic at that time. And I think it's not easy to prove it's useless thesedays because I couldn't have all recent workloads over the world so I'd like to avoid such adventure. :) Thanks. > > Thanks, > -Kame > > > -- > 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> -- Kind regards, Minchan Kim -- 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>