Messages in this thread | | | Date | Mon, 3 Dec 2001 18:23:35 -0800 (PST) | From | Davide Libenzi <> | Subject | Re: Linux/Pro -- clusters |
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On Mon, 3 Dec 2001, Donald Becker wrote:
> On Mon, 3 Dec 2001, Davide Libenzi wrote: > > > On Mon, 3 Dec 2001, Donald Becker wrote: > > > of the change. We won't know for years if redesigning the kernel for > > > large scale SMP system is useful > > > - does it actually work, > > > - will big SMP machines be common, or even exist? > > > - will big SMP machines have the characteristics we predict > > > let alone worth the costs such as > > > - UP performance hit > > > - complexity increase slows other improvements > > > - difficult performance tuning > ... > > No, I do not believe in 128 single CPU SMP machines but, if I've to watch > > inside my pretty dirty crystal ball, I see multi-core CPUs as a technology > > response to SMP request. > > Yes, because after the 1st theorem of "work" there's the 1st lemma of > > technology that states that "technology will always follow the > > market request". > > You haven't addressed the points above. > We haven't established that the market will request substantial numbers > of 128-way SMPs. Even if they do request single-address-space > multiprocessors, it's very likely that the result will be some form of cc-numa > where the structure will strongly influence the OS to treat the machine > as something besides a SMP. > > To bring this branch back on point: we should distinguish between > design for an arbitrary and unpredictable goal (e.g. 128 way SMP) > vs. putting some design into things that we are supposed to already > understand > a SCSI device layer that isn't three half-finished clean-ups > a VFS layer that doesn't require the kernel to know a priori all of > the filesystem types that might be loaded
Donald, I'm not even thinking about planning a 128 CPU scalability for Linux. The whole point of this discussion ( if any ) is that we've to design on what we've or on what we expect to have in a very near future. We cannot play with technology on long term plans because, no matter how good we plan, it'll screw us up.
- Davide
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