On Tue, 15 Aug 2017 13:49:45 +0800 Aaron Lu <aaron...@intel.com> wrote:
> On Mon, Aug 14, 2017 at 04:33:37PM -0700, Andrew Morton wrote: > > On Mon, 14 Aug 2017 13:31:30 +0800 Aaron Lu <aaron...@intel.com> wrote: > > > > > --- /dev/null > > > +++ b/Documentation/vm/swap_numa.txt > > > @@ -0,0 +1,18 @@ > > > +If the system has more than one swap device and swap device has the node > > > +information, we can make use of this information to decide which swap > > > +device to use in get_swap_pages() to get better performance. > > > + > > > +The current code uses a priority based list, swap_avail_list, to decide > > > +which swap device to use and if multiple swap devices share the same > > > +priority, they are used round robin. This change here replaces the single > > > +global swap_avail_list with a per-numa-node list, i.e. for each numa > > > node, > > > +it sees its own priority based list of available swap devices. Swap > > > +device's priority can be promoted on its matching node's swap_avail_list. > > > + > > > +The current swap device's priority is set as: user can set a >=0 value, > > > +or the system will pick one starting from -1 then downwards. The priority > > > +value in the swap_avail_list is the negated value of the swap device's > > > +due to plist being sorted from low to high. The new policy doesn't change > > > +the semantics for priority >=0 cases, the previous starting from -1 then > > > +downwards now becomes starting from -2 then downwards and -1 is reserved > > > +as the promoted value. > > > > Could we please add a little "user guide" here? Tell people how to set > > up their system to exploit this? Sample /etc/fstab entries, perhaps? > > That's a good idea. > > How about this: > > ... > Looks good. Please send it along as a patch some time? > > I'm not sure what to do...any hint? > Adding a pr_err() perhaps? pr_emerg(), probably. Would it make sense to disable all swapon()s after this?
