On Mon, 19 Aug 2013, Frank Mayhar wrote: > On Mon, 2013-08-19 at 10:00 -0400, Mike Snitzer wrote: > > Performance isn't the concern. The concern is: does DM allow for > > forward progress if the system's memory is completely exhausted? > > > > This is why request-based has such an extensive reserve, because it > > needs to account for cloning the largest possible request that comes in > > (with multiple bios). > > Thanks for the response. In our particular case, I/O will be file > system based and over a network, which makes it pretty easy for us to be > sure that large I/Os never happen. That notwithstanding, however, as > you said it just seems reasonable to make these values configurable. > > I'm also looking at making some similar constants in dm-verity and > dm-bufio configurable in the same way and for similar reasons. Regarding dm-bufio: the user of dm-bufio sets the pool size as an argument in dm_bufio_client_create. There is no need to make it configurable - if the user selects too low value, deadlock is possible, if the user selects too high value, there is no additional advantage. Regarding dm-verity: the mempool size is 4, there is no need to make it bigger, there is no advantage from that. Mikulas -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
