Jeff Squyres wrote: > I was trying to use hwloc-bind this morning, and I was a bit confused by the > syntax. I see that the help message says: > > ----- > Usage: topobind [options] <location> -- command ... > <location> may be a space-separated list of cpusets or objects > as supported by the hwloc-mask utility. > ----- > > (shouldn't that say hwloc-bind, not topobind?) >
Right :) > I assume the <string> here in hwloc-mask is the same as the <location> in > hwloc-bind. > Yes. > 1. Is the index syntax "X,Y[,Z[...]]" supported? I don't see it on the list, > but was curious if it is supported anyway. E.g., "proc:0,1,4". No I don't think it's supported right now. > That would seem useful (slightly shorter than "proc:0.proc:1.proc:4"). I > can file a feature request if it's not already supported. > Actually, it would proc:0 proc:1 proc:4 (space separated). hwloc-bind/mask do a logical/cpuset OR of all objects/masks given on the command-line. > 2. What does it mean to "hwloc-bind core:0 ..."? (I asked Samuel this in IM > as well, but I didn't understand his answer). *Which* "core 0" does that > refer to? For example, an abbreviated version of my lstopo output is as > follows (it's a pre-production EX machine -- I can't share all the details -- > I 'x'ed out some of the numerical values): > > ----- > System(xxxGB) > Node#0(xxxGB) + Socket#0 + L3(xxxMB) > L2(xxxKB) + L1(xxxKB) + Core#0 + P#0 > ... > Node#1(xxxGB) + Socket#2 + L3(xxxMB) > L2(xxxKB) + L1(xxxKB) + Core#0 + P#1 > ... > ----- > > The processors have unique numbers, but the cores do not. Is that a bug? > These are physical/OS indexes, not logical indexes. hwloc-bind/mask takes logical indexes, no it has nothing to do with the above #N. core:1 means "the second Core object" when you the above output from top to bottom. > 3. What is the difference between "system" and "machine"? > Machine is a physical machine. System may be be different in case of Single System Image like Kerrighed, vSMP, ... (only Kerrighed is supported so far). > 4. What exactly does "index" refer to -- is it a virtual index (e.g., hwloc's > numbering of 0-N) or is it the OS's index? I thought we used OS index > numbering, but #2 confuses me -- if #2 is just a bug, then perhaps this > question is moot. :-) > We use virtual/logical/OS index everywhere, except in the lstopo output and in the functions that contain os_index in their prototype. > 5. What exactly is a "cpuset string"? Can some examples be provided? > It's 0 for nothing, ffffffff for 32procs, 1,,,,,,,,1 for the the first and the 257th processors. It's a comma separated list of 32bits bitmak. > --> Sidenote: I actually find hwloc's use of the word "cpuset" to be quite > confusing because it is *NOT* the same as an OS cpuset. The structure might be a bit different, but it is conceptually the same than the OS cpuset. When bit N is set in a hwloc cpuset, it means we are talking about the processor whose *OS-index* is N. > 6. "several <depth:index> may be concatenated with `.'..." Does that mean > that this is legal: > > core:0.node:2.system:4 > > If so, what exactly does it mean when they overlap? Is it simply the union > of those 3 specifications? It means 5th logical system below 3rd logical node below first core. So it means nothing when there are no node objects below cores or no systems below nodes. > Also, I'm curious -- why was a period chosen as the delimiter instead of a > comma? Is this a Europe-vs-US thing? (i.e., in the US, we typically use > commas for lists -- is it different in Europe?) > We use commas for lists in Europe too. But The above is not a list, it's a inclusion. See it as core[0].node[2].system[4] in C language. Brice
