BLU Discuss list archive
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[Discuss] Whence distributed operating systems?
- Subject: [Discuss] Whence distributed operating systems?
- From: bogstad at pobox.com (Bill Bogstad)
- Date: Thu, 28 Apr 2016 20:30:44 -0400
- In-reply-to: <3ba90ee1-0558-d121-a95d-a744fdbe32ff@gmail.com>
- References: <chx4mavtvj8.fsf@iceland.freeshell.org> <20160421121138.GU12314@randomstring.org> <CAFq0N1z2xg2u0e6zbP8Aenyv1YAcW1C51vriQrj2V6XTh8KzpQ@mail.gmail.com> <571CD9C0.8030808@gmail.com> <CAJFsZ=r6YO9fW1js-h_C2JcUPi7fLCZiYzAHtq6P0L1D3Aw8GQ@mail.gmail.com> <3ba90ee1-0558-d121-a95d-a744fdbe32ff@gmail.com>
On Thu, Apr 28, 2016 at 3:17 PM, Rich Pieri <richard.pieri at gmail.com> wrote: > On 4/28/2016 4:28 AM, Bill Bogstad wrote: >> So memory was shared? between the QBBs? This sounds more like a NUMA >> architecture environment. What would you say are the differences >> between this definition >> of SSI and NUMA? > > In a NUMA machine, memory is directly attached to the CPUs but not all > of that memory is local to each CPU. Galaxy wasn't NUMA. Each QBB was > NUMA: 4 processors with 512MB local to each with the rest being > non-local but still directly attached. Memory in one QBB was not > directly attached to the processors in other QBBs; it was shared via > software over a fibre data bus. Can you clarify what you mean by "shared via software"? Did the virtual memory system, page fault data from remote QBBs as needed or was there a fibre bus transaction every time a local process accessed remote memory? I understood your original note to mean that from a programs perspective it could allocate/use memory in other QBBs transparently (except for possible performance differences). The fact that this was done via a fibre data bus vs. a faster local bus would seem to me to be an implementation detail. It still sounds like a NUMA with three levels of memory access (CPU local, QBB local, remote QBB). But all of the memory transparently visible in a program's address space. Bill Bogstad
- Follow-Ups:
- [Discuss] Whence distributed operating systems?
- From: richard.pieri at gmail.com (Rich Pieri)
- [Discuss] Whence distributed operating systems?
- References:
- [Discuss] Whence distributed operating systems?
- From: smallm at sdf.org (Mike Small)
- [Discuss] Whence distributed operating systems?
- From: dsr at randomstring.org (Dan Ritter)
- [Discuss] Whence distributed operating systems?
- From: jack at coats.org (Jack Coats)
- [Discuss] Whence distributed operating systems?
- From: richard.pieri at gmail.com (Rich Pieri)
- [Discuss] Whence distributed operating systems?
- From: bogstad at pobox.com (Bill Bogstad)
- [Discuss] Whence distributed operating systems?
- From: richard.pieri at gmail.com (Rich Pieri)
- [Discuss] Whence distributed operating systems?
- Prev by Date: [Discuss] Looking for a replacement RSS/Atom feed reader extension for use with Firefox
- Next by Date: [Discuss] Whence distributed operating systems?
- Previous by thread: [Discuss] Whence distributed operating systems?
- Next by thread: [Discuss] Whence distributed operating systems?
- Index(es):