> > > > > Is not the max 64K as you test against XDP_UMEM_MAX_CHUNK_SIZE in > > > > > xdp_umem_reg()? > > > > > > > > The absolute max is 64K. In the case of HPAGE_SIZE < 64K, then it > > > > would be HPAGE_SIZE. > > > > > > Is there such a case when HPAGE_SIZE would be less than 64K? If not, > > > then just write 64K. > > > > Yes. While most platforms have HPAGE_SIZE defined to a compile-time > > constant >= 64K (very often 2M) there are platforms (at least ia64 and > > powerpc) where the hugepage size is configured at boot. Specifically, > > in the case of Itanium (ia64), the hugepage size may be configured at > > boot to any valid page size > PAGE_SIZE (e.g. 8K). See: > > https://elixir.bootlin.com/linux/latest/source/arch/ia64/mm/hugetlbpage.c#L159 > > So for all practical purposes it is max 64K. Let us just write that then. What about when CONFIG_HUGETLB_PAGE is not defined? Should we keep it set to PAGE_SIZE in that case, or would you like it to be a fixed constant == 64K always? > > > > > > > > > > static int xdp_umem_pin_pages(struct xdp_umem *umem, unsigned long address) > > > > > > { > > > > > > +#ifdef CONFIG_HUGETLB_PAGE > > > > > > > > > > Let us try to get rid of most of these #ifdefs sprinkled around the > > > > > code. How about hiding this inside xdp_umem_is_hugetlb() and get rid > > > > > of these #ifdefs below? Since I believe it is quite uncommon not to > > > > > have this config enabled, we could simplify things by always using the > > > > > page_size in the pool, for example. And dito for the one in struct > > > > > xdp_umem. What do you think? > > > > > > > > I used #ifdef for `page_size` in the pool for maximum performance when > > > > huge pages are disabled. We could also not worry about optimizing this > > > > uncommon case though since the performance impact is very small. > > > > However, I don't find the #ifdefs excessive either. > > > > > > Keep them to a minimum please since there are few of them in the > > > current code outside of some header files. And let us assume that > > > CONFIG_HUGETLB_PAGE is the common case. > > > > > > > Would you be OK if I just remove the ones from xsk_buff_pool? I think > > the code in xdp_umem.c is quite readable and the #ifdefs are really > > only used in xdp_umem_pin_pages. > > Please make an effort to remove the ones in xdp_umem.c too. The more > ifdefs you add, the harder it will be to read. OK
