Messages in this thread | | | Date | Fri, 12 Jan 2007 13:22:03 +0800 | From | Aubrey <> | Subject | Re: O_DIRECT question |
| |
On 1/12/07, Nick Piggin <nickpiggin@yahoo.com.au> wrote: > Linus Torvalds wrote: > > > > On Fri, 12 Jan 2007, Nick Piggin wrote: > > > >>We are talking about about fragmentation. And limiting pagecache to try to > >>avoid fragmentation is a bandaid, especially when the problem can be solved > >>(not just papered over, but solved) in userspace. > > > > > > It's not clear that the problem _can_ be solved in user space. > > > > It's easy enough to say "never allocate more than a page". But it's often > > not REALISTIC. > > > > Very basic issue: the perfect is the enemy of the good. Claiming that > > there is a "proper solution" is usually a total red herring. Quite often > > there isn't, and the "paper over" is actually not papering over, it's > > quite possibly the best solution there is. > > Yeah *smallish* higher order allocations are fine, and we use them all the > time for things like stacks or networking. > > But Aubrey (who somehow got removed from the cc list) wants to do order 9 > allocations from userspace in his nommu environment. I'm just trying to be > realistic when I say that this isn't going to be robust and a userspace > solution is needed. > Hmm..., aside from big order allocations from user space, if there is a large application we need to run, it should be loaded into the memory, so we have to allocate a big block to accommodate it. kernel fun like load_elf_fdpic_binary() etc will request contiguous memory, then if vfs eat up free memory, loading fails.
-Aubrey - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |