On Wed, 25 Apr 2007, Eric Dumazet wrote: > > struct radix_tree_root page_tree; /* radix tree of all pages */ > > rwlock_t tree_lock; /* and rwlock protecting it */ > > +#ifdef CONFIG_LARGE_BLOCKSIZE > > + unsigned int order; /* Page order of the pages in > > here */ > > + unsigned int shift; /* Shift of index */ > > + loff_t offset_mask; /* Mask to get to offset bits > > */ > > +#endif > > unsigned int i_mmap_writable;/* count VM_SHARED mappings */ > > struct prio_tree_root i_mmap; /* tree of private and shared > > mappings */ > > struct list_head i_mmap_nonlinear;/*list VM_NONLINEAR mappings > > */ > > Some comments about this : > > 1) not optimal placement on 64bits arches (it creates one hole before > i_mmap_writeable)
loff_t is a 64 bit long. We could put shift behind offset_mask. > 2) sizeof(struct address_space) is an issue, given it is included in every > inode, even sockets or pipes. Right. I had an earlier implementation that just used an order field. See V2 of this patchset. That did a lot of shifting instead of lookups. > -> 2.1) Do we really need 32 bits for 'order' and 'shift' No. u8 would be sufficient. If you can stuff in other stuff in between then I can switch it. > -> 2.2) Do we really need a 64bits offset_mask since it's a trivial arithmetic > from 'shift' (or 'order') ? It simplifies the generated asm code significantly. > BTW, I presume splice() is not yet supported ? If yes, each pipe could hold 16 > 'big pages' so we probably can hit some DOS condition sooner... Not yet. I'd be glad if you could come up with a patch that converts it. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
