On Tue, 2003-09-02 at 11:01, Vivek Khera wrote: > >>>>> "AS" == Andrew Sullivan <[EMAIL PROTECTED]> writes: > > AS> On Fri, Aug 29, 2003 at 12:05:03AM -0700, William Yu wrote: > >> We should see a boost when we move to 64-bit Linux and hopefully another > >> one when NUMA for Linux is production-stable. > > AS> According to the people who've worked with SGIs, NUMA actually seems > AS> to make things worse. It has something to do with how the shared > AS> memory is handled. You'll want to dig through the -general or > AS> -hackers archives from somewhere between 9 and 14 months ago, IIRC. > > I knew my PhD research would one day be good for *something* ... > > The basic premise of NUMA is that you can isolate which data belongs > to which processor and put that on memory pages that are local/closer > to it. In practice, this is harder than it sounds as it requires very > detailed knowledge of the application's data access patterns, and how > memory is allocated by the OS and standard libraries. Often you end > up with pages that have data that should be local to two different > processors, and that data keeps being migrated (if your NUMA OS > supports page migration) between the two processors or one of them > just gets slow access. > > I can't imagine it benefiting postgres given its globally shared > buffers.
Opteron is supposed to have screaming fast inter-CPU memory xfer (HyperTransport does inter-CPU as well as well as CPU-RAM transport). That's supposed to help with scaling, and PostgreSQL really may take advantage of that, with, say 16-32 processors? -- ----------------------------------------------------------------- Ron Johnson, Jr. [EMAIL PROTECTED] Jefferson, LA USA "Knowledge should be free for all." Harcourt Fenton Mudd, Star Trek:TOS, "I, Mudd" ---------------------------(end of broadcast)--------------------------- TIP 9: the planner will ignore your desire to choose an index scan if your joining column's datatypes do not match