Michal Suchánek <msucha...@suse.de> writes: > On Thu, 17 Jan 2019 23:13:28 +1100 > Michael Ellerman <m...@ellerman.id.au> wrote: > >> On machines with 1TB segments and a 32-entry SLB it's quite hard to >> cause sufficient SLB pressure to trigger bugs caused due to badly >> timed SLB faults. >> >> We have seen this in the past and a few years ago added the >> disable_1tb_segments command line option to force the use of 256MB >> segments. However even this allows some bugs to slip through testing >> if the SLB entry in question was recently accessed. >> >> So add a new command line parameter for debugging which shrinks the >> SLB to the minimum size we can support. Currently that size is 3, two >> bolted SLBs and 1 for dynamic use. This creates the maximal SLB > > Doesn't this violate the power of 2 requirement stated in 2/4?
Yes. Good point. This was originally a hack patch in my tree, back when SLB_NUM_BOLTED was 3 and before Nick even added the slb_used_bitmap, so back then it was a power of 2 but it also didn't matter :) I think I'll rework the slb_full_bitmap patch anyway and remove the power of 2 requirement, so then this patch will be OK. Thanks for the review! cheers
