On Wed, Jan 19, 2022 at 09:44:20PM +0800, Kefeng Wang wrote: > > On 2022/1/19 21:22, Matthew Wilcox wrote: > > On Wed, Jan 19, 2022 at 08:57:58PM +0800, Kefeng Wang wrote: > > > Only parts of our products wants this feature, we add some interfaces which > > > only > > > > > > alloc hugevmalloc for them, eg, > > > vmap_hugepage/vmalloc_hugepage/remap_vmalloc_hugepage_range.. > > > > > > for our products, but it's not the choice of most products, also add > > > nohugevmalloc > > > > > > for most products is expensive, so this is the reason for adding the patch. > > > > > > more config/cmdline are more flexible for test/products, > > But why do only some products want it? What goes wrong if all products > > enable it? Features should be auto-tuning, not relying on admins to > > understand them. > > Because this feature will use more memory for vmalloc/vmap, that's why we > add some explicit > interfaces as said above in our kernel to control the user. Have you validated that? What sort of performance penalty do you see?