1. 12 Jan, 2004 1 commit
    • Robert Ricci's avatar
      Several changes, mostly targeted at jail and simulation-type · 3a345f8e
      Robert Ricci authored
      topologies.
      
      First, added a new 'summary' of the solution, when the '-u' option is
      given. It's a view of things from the physical side - prints out how
      many vnodes were mapped to each pnode, as well as how much bandwidth
      (trivial and non-trivial) was used on each node. For 'normal' nodes,
      we also print out all links used and how much bandwidth was used on
      each of them. For switches, we print only inter-switch links. This is
      amazingly helpful in getting an intuitive feel for how well assign is
      doing.
      
      Added a SIGINFO handler for the impatient (like me) to see things such
      as the current temperature, and current and best scores, while assign
      is running.
      
      Fixed a bug in which emulated links could get over-subscribed, as well
      as a few other misc. bugfixes.
      
      Changed the way assign goes through the list of a node's pclasses in
      random order - there were problems with the old way in which you could
      end up with a situation in which some pnodes were chosen with a much
      higher probability than others. Now, rather than treating the list as
      a ring and starting at a random place, we make a randomly-ordered list
      of the pclasseses, and go through it from start to finish.
      
      Did some work on dynamic pclasses so that we adjust the estimate of
      the neighborhood size to account for disabled pclasses (ie. pnodes
      that have nothing mapped to them yet.)
      
      Changed the way that find_link_to_switch() decides on the best link to
      use - the old method was doing very poorly at bin-packing emulated
      links into plinks. I now use a simple first-fit algorithm. This made a
      pretty big difference. I may try some other fast bin-packing
      approximation algorithm, but my main fear is that all of the good ones
      (such as the 'sort from largest to smallest, then do first-fit'
      algorithm) may require re-mapping other links. This might be slow,
      and/or it might make it difficult, if not impossible, to keep
      add_node() and remove_node() symmetric.
      
      Combinded direct_link() and find_link_to_switch() into
      find_best_link(), since they really do the same thing.
      
      Standardized on std::random() to get random numbers - previosuly, some
      calls were using std::rand().
      
      The big one: I added a find_pnode_connected() function that finds a
      random pnode that one of the vnode's neighbors in the virtual graph is
      assigned to. Then, with a random probability (given with the -c option
      on the command line), we try that function to find a pnode first (if
      it fails, we still call find_pnode() ). Of course, this is only really
      applicable when you have a reasonable degree of vnode-to-pnode
      multiplexing. In the test case I'm using, this managed to get 3x as
      much bandwidth into trivial links as just using find_pnode().
      3a345f8e
  2. 15 Sep, 2003 1 commit
    • Robert Ricci's avatar
      Some fixes aimed at vnodes: · 7848e357
      Robert Ricci authored
      Don't allow intraswitch links to vnodes on switches - they'll get
      scored as direct links. Since LANs are now directly on switches, there
      were situations where we could have scored the same link as either
      direct or intraswitch, which results in two different scores. This can
      cause those 'contact calfeld' warnings, and might have caused some
      strange scoring fluxuations as assign ran.
      
      When picking a link to a switch, for emulated links, pick the least
      loaded link, not the one with the fewest users. This helps in situations
      where the link bandwidths are heterogenous.
      7848e357
  3. 11 Sep, 2003 2 commits
  4. 08 Sep, 2003 1 commit
  5. 04 Sep, 2003 1 commit
  6. 01 Jul, 2003 1 commit
    • Robert Ricci's avatar
      Give assign the ability to make dynamic pclasses. Here's how it works: · fbcd6752
      Robert Ricci authored
      After building the set of pclasses normally, we make another pass
      through the vnodes. The goal to create a pclass for each individual
      node. We disable the node's 'own' pclass to begin with. Then, the
      _first_ time it gets a vnode mapped to it, we remove it from the
      'regular' pclass it belongs to, and enable it's own pclass. Then, if
      it goes empty, we put it back in its regular pclass and disable it's
      own.
      
      The point of this is to replace -p for use with multiplexed nodes.
      Instead of disabling pclasses altogheter, which has serious
      performance implications, we can instead be smart about which pnodes
      remain equivalent (because nothing's been mapped to them), and which
      are now different. The result is that on my test topoloy, the time to
      get a good mapping has gone from over 3 minutes to about 6 seconds.
      
      This feature is enabled with the -d option, and the -P option is
      pretty much mandatory when using it, since it greatly exacerbates the
      problem of cruft in the ptop file.
      
      This satisfies #14 from the todo file:
      14.  do dynamic pclasses
      
      Also bumped up the minimum neighborhood size from 500 to 1000. In some
      tests I was doing, this resulted in better solutions.
      fbcd6752
  7. 26 Jun, 2003 2 commits
    • Robert Ricci's avatar
      Change around some data structures to make certain functions faster - · 55566879
      Robert Ricci authored
      turns out that getting iterators to the STL hash_* data structures is
      really slow, so for some that won't be very big, use the non-hash
      version.
      
      Buys something like a 30% speedup for large topologies.
      55566879
    • Robert Ricci's avatar
      Major changes to the way assign handles LAN nodes. · 83cfa8ec
      Robert Ricci authored
      LAN nodes are no longer treated specially. Instead, I've introduced
      the idea of 'static' types (old-style types retroactively become
      'dynamic' types). While a pnode can only satisfy one dynamic type at a
      time, it can always satisfy its static types (assuming it has enough
      capacity left.) Static types are flagged by prepending them with a '*'
      in the ptop file. So, for example, you may give switches the
      '*lan:10000' type so that they can satisfy virtual LAN nodes. Of
      course, other pnodes can have this type too, so that we can get
      'trivial LANs'.
      
      Actually, removing special treatment for LANs cleans up a lot of code.
      However, it may have some negative impacts on solutions, since we're
      not as smart about where to place LAN nodes as we used to be (they get
      annealed along with everything else, and not migrated.) I haven't seen
      any evidence of this yet, however.
      
      This leaves us with a single type of special pnode, a switch.
      
      Also added a new bit of syntax in ptop files - when '*' is given as a
      the maxiumum load for a type, the node is allowed to take on an
      infinite (well, actually, just a really big number of) vnodes of that
      type.
      
      ptopgen was modified to always report switches as being capable of
      hosting LANs, and assign_wrapper now understands direct links to LANs,
      which is what we get when the LAN is hosted directly on a switch.
      
      Fixed a bug in scoring direct links, in which the penatly was being
      added once when a direct link was mapped, but subtracted only once
      when it was freed.
      
      Added a '-T' option for doing simple self-testing. When adding a node
      to the solution, assign records the score, adds the node, removes it
      again, and checks to make sure that the resulting score is the same as
      the original score. The usefulness of this feature in debugging
      scoring problems cannot be understated...
      83cfa8ec
  8. 20 Jun, 2003 1 commit
  9. 28 May, 2003 1 commit
    • Robert Ricci's avatar
      Added the TRIVIAL_LINK_BW option, which allows, in the ptop file, · 5c67bf1f
      Robert Ricci authored
      specification of how much bandwidth can be used on the node for
      trivial links. Clearly, there will be some limit to loopback
      transfers, and this makes assign aware of it.
      
      While I was in there, cleaned up and commented some of the code I was
      working on.
      
      Also fixed a bug with the type pre-check and emulated links that are
      trivial_ok - we can't add these into the total for a vnode, because
      they could end up being satisified with trivial links.
      5c67bf1f
  10. 16 Apr, 2003 1 commit
    • Robert Ricci's avatar
      Fix PER_VNODE_TT to work with vclasses and emulated links. Now, we can turn it · 690ec56d
      Robert Ricci authored
      on in production!
      
      PER_VNODE_TT handles emulated links by simply adding up the total bandwidth
      consumed by a vnode, and the total bandwidth available on each pnode. Of
      course, this can lead to false positives (knapsack problem), but that's okay,
      because it just means we won't bail up front - we'll have to do the full
      annealing pass before we decide it's unmappable.
      
      PER_VNODE_TT now also tries to figure out why a vnode is not mappable - if
      there are _no_ pclasses that match one of the restrictions, it will print out
      something like:
        *** No possible mapping for nodeA
            Too many links!
        *** No possible mapping for nodeB
            Too much bandwidth on emulated links!
      
      This completes the following two items from assign_todo.txt:
      
      6.   fix PER_VNODE_TT and vclasses
      7.   fix PER_VNODE_TT and emulated vlinks
      690ec56d
  11. 10 Mar, 2003 1 commit
  12. 05 Mar, 2003 1 commit
  13. 10 Feb, 2003 1 commit
  14. 04 Feb, 2003 1 commit
  15. 03 Jul, 2002 1 commit
  16. 29 May, 2002 1 commit
  17. 02 Jan, 2002 1 commit
    • Christopher Alfeld's avatar
      · 1eb1e1d9
      Christopher Alfeld authored
      This check-in consists of 7 modifications to assign.
      
      1. Equivalence Classes
      
      Defined an equivalence relation on the physical nodes and applied it
      to the physical topology to get the resulting quotient topology (abuse
      of terminology).  So instead of searching among all possible physical
      nodes to make a map, assign only searches among all possible
      equivalence classes of nodes.  This tremendously reduces the search
      space.  At the time of this writing it reduces the physical topology
      from 252 nodes to 13 nodes.  The equivalence classes are generated
      automatically from the ptop file.
      
      2. Scoring based on equivalence classes.
      
      Each equivalence class used comes with a significant cost.  This
      strongly encourages assign to use equivalence machines when possible.
      The result is that an experiment that does not otherwise specify will
      almost definitely get machines of the same type.  If this needs to be
      reduced in the future it is the SCORE_PCLASS constant.
      
      3. Heuristics
      
      Added a bunch of heuristics for choosing which equivalence class to
      use.  This was less successful than I hoped.  A good solution is now
      found in record time but it still continues searching.  When OPTIMAL
      is turned on these heuristics help a lot.  When off they make little
      difference.  I may turn this into a compile time option in the future
      since the heuristics do take non-trivial CPU cycles.
      
      4. Fixed the very-very-big-and-evil disconnected-switches bug.
      
      Assign wasn't cleaning up after itself in certain cases.  Disconnected
      graphs are now merely a minor, easily ignored, bump rather than the
      towering cliffs they use to be.
      
      5. Fixed the not-yet-noticed not-enough-nodes bug.
      
      Found a bug that probably has never come up before because we have
      checks that avoid those circumstances.
      
      6. Modified constants.
      
      I was tired of waiting so long for results so, I lowered CYCLES and
      reduced the constant for naccepts (Mac, you probably want to add that
      inconspicuous number to your configurable constants; look for
      "naccepts =").  The results is roughly a speedup of 2.  It works great
      currently but we may want to change these numbers up again if we get
      problems with features and desires.
      
      7. General clean up.
      
      Associated with the other changes was a lot of restructuring and some
      cleanup.  Specifically to the assign loop and scoring code.
      1eb1e1d9
  18. 20 Jul, 2001 1 commit
    • Christopher Alfeld's avatar
      This is a nearly complete rewrite of the assign interswitch code. Assign · 8078740b
      Christopher Alfeld authored
      now precomputers the shortest path between all pairs of switches and uses
      this to computer paths through the switch fabric.  In the process of
      writing this I also removed the limitations of two switch hops.  Packets
      can now travel through any number of switches to reach their destination.
      Of course, the longer the path the more it costs so assign will prefer
      shorter paths.
      
      Also did various other tweaks in the process.  We now use strings almost
      everywhere instead of char*'s and the makefile is cleaner.
      8078740b
  19. 14 Mar, 2001 1 commit
  20. 25 Aug, 2000 1 commit