On Thu, Mar 30, 2017 at 08:45:56AM +0800, Huang, Ying wrote: > Johannes Weiner <han...@cmpxchg.org> writes: > > > On Tue, Mar 28, 2017 at 01:32:01PM +0800, Huang, Ying wrote: > >> @@ -499,6 +499,19 @@ config FRONTSWAP > >> > >> If unsure, say Y to enable frontswap. > >> > >> +config ARCH_USES_THP_SWAP_CLUSTER > >> + bool > >> + default n > > > > This is fine. > > > >> +config THP_SWAP_CLUSTER > >> + bool > >> + depends on SWAP && TRANSPARENT_HUGEPAGE && ARCH_USES_THP_SWAP_CLUSTER > >> + default y > >> + help > >> + Use one swap cluster to hold the contents of the THP > >> + (Transparent Huge Page) swapped out. The size of the swap > >> + cluster will be same as that of THP. > > > > But this is a super weird thing to ask the user. How would they know > > what to say, if we don't know? I don't think this should be a config > > knob at all. Merge the two config items into a simple > > The user will not see this, because there is no string after "bool" to > let user to select it. The help here is for document only, so that > architecture developers could know what this is for.
Oh, I missed that. My bad! > > config THP_SWAP_CLUSTER > > bool > > default n > > > > and let the archs with reasonable THP sizes select it. > > This will have same effect as the original solution except the document > is removed. Then I still don't understand why we need two config symbols. Can't archs select the documented THP_SWAP_CLUSTER directly? The #ifdef in swapfile.c could check THP && THP_SWAP_CLUSTER. Am I missing something?
