Messages in this thread | | | Date | Sat, 22 Feb 2003 15:10:48 -0800 | From | "Martin J. Bligh" <> | Subject | Re: Minutes from Feb 21 LSE Call |
| |
>> OK, so now you've slid from talking about PCs to 2-way to 4-way ... >> perhaps because your original arguement was fatally flawed. > > oh, come on. the issue is whether memory is fast and flat. > most "scalability" efforts are mainly trying to code around the fact > that any ccNUMA (and most 4-ways) is going to be slow/bumpy.
Scalability is not just NUMA machines by any stretch of the imagination. It's 2x, 4x, 8x SMP as well.
> it is reasonable to worry that optimizations for imbalanced machines > will hurt "normal" ones. is it worth hurting uni by 5% to give > a 50% speedup to IBM's 32-way? I think not, simply because > low-end machines are more important to Linux.
We would never try to propose such a change, and never have. Name a scalability change that's hurt the performance of UP by 5%. There isn't one.
> ccNUMA worst-case latencies are not much different from decent > cluster (message-passing) latencies. getting an app to work on a cluster > is a matter of programming will.
It's a matter of repeatedly reimplementing a bunch of stuff in userspace, instead of doing things in kernel space once, properly, with all the machine specific knowledge that's needed. It's *so* much easier to program over a single OS image.
M.
- 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/
| |