snabbmark: Add "mp-ring" multiprocess benchmark

src/program/snabbmark/mp.lua

@@ -0,0 +1,114 @@
+-- Multiprocess benchmarks
+-- Use of this source code is governed by the Apache 2.0 license; see COPYING.
+
+module(..., package.seeall)
+
+local ffi = require("ffi")
+local C = ffi.C
+local S = require("syscall")
+local pmu = require("lib.pmu")
+local lib = require("core.lib")
+
+-- Ring benchmark:
+-- See how quickly packets are cycled through a ring of processes.
+--
+-- Each process copies packets from its input to its output link. Each
+-- link is populated with an initial "burst" of packets.
+function mp_ring (args)
+   local function usage ()
+      print(require("program.snabbmark.README_mp_inc"))
+      os.exit(1)
+   end
+   local long_opts = {
+      help = "h",
+      mode = "m",
+      processes = "n",
+      packets = "p",
+      burst = "b",
+      events = "e",
+      read = "r",
+      write = "w"
+   }
+   local c = {
+      mode = "basic",
+      processes = 2,
+      packets = 100e6,
+      burst = 100,
+      pmuevents = false,
+      readbytes = 0,
+      writebytes = 0
+   }
+   local opt = {}
+   function opt.m (arg) c.mode = arg end
+   function opt.n (arg) c.processes = tonumber(arg) end
+   function opt.p (arg) c.packets = tonumber(arg) end
+   function opt.b (arg) c.burst = tonumber(arg) end
+   function opt.e (arg) c.pmuevents = arg end
+   function opt.r (arg) c.readbytes = tonumber(arg) end
+   function opt.w (arg) c.writebytes = tonumber(arg) end
+   function opt.h (arg) usage() end
+   local leftover = lib.dogetopt(args, opt, "hn:p:b:e:r:w:", long_opts)
+   if #leftover > 0 then usage () end
+   -- Print summary of configuration
+   print("Benchmark configuration:")
+   for k, v in pairs(c) do
+      print(("%12s: %s"):format(k,v))
+   end
+   links = {}
+   -- Create links to connect the processes in a loop
+   for i = 0, c.processes-1 do
+      links[i] = link.new(tostring(i))
+      for j = 1, c.burst do
+         link.transmit(links[i], packet.allocate())
+      end
+   end
+   -- Create per-process counters
+   local counters = ffi.cast("uint64_t *",
+                             memory.dma_alloc(c.processes*ffi.sizeof("uint64_t")))
+   -- Start child processes
+   if c.pmuevents then error("PMU support NYI") end
+   local start = C.get_time_ns()
+   for i = 0, c.processes-1 do
+      if S.fork() == 0 then
+         -- Child <i> has affinity to CPU core <i>
+         S.sched_setaffinity(0, i)
+         -- terminate when parent does
+         S.prctl("set_pdeathsig", "hup")
+         local input = links[i]
+         local output = links[(i+1) % c.processes]
+         if c.mode == "basic" then
+            -- Simple reference implementation in idiomatic Lua.
+            local acc = ffi.new("uint8_t[1]")
+            while counters[i] < c.packets do
+               if not link.empty(input) and not link.full(output) then
+                  local p = link.receive(input)
+                  -- Read some packet data
+                  for j = 0, c.readbytes do
+                     acc[0] = acc[0] + p.data[j]
+                  end
+                  -- Write some packet data
+                  for j = 0, c.writebytes do
+                     p.data[j] = i
+                  end
+                  link.transmit(output, p)
+                  counters[i] = counters[i] + 1
+               end
+               -- Sync registers with memory
+               core.lib.compiler_barrier()
+            end
+         else
+            print("mode not recognized: " .. c.mode)
+            os.exit(1)
+         end
+         os.exit(0)
+      end
+   end
+   -- Spin until enough packets have been processed
+   while counters[0] < c.packets do
+      core.lib.compiler_barrier()
+   end
+   local finish = C.get_time_ns()
+   local seconds = tonumber(finish-start)/1e9
+   local packets = tonumber(counters[0])
+   print(("%7.2f Mpps ring throughput per process"):format(packets/seconds/1e6))
+end

src/program/snabbmark/snabbmark.lua

@@ -22,6 +22,8 @@ function run (args)
       solarflare(unpack(args))
    elseif command == 'intel1g' and #args >= 2 and #args <= 3 then
       intel1g(unpack(args))
+   elseif command == 'mp-ring' then
+      require("program.snabbmark.mp").mp_ring(args)
    else
       print(usage) 
       main.exit(1)