diff options
| author | Boris Kolpackov <boris@codesynthesis.com> | 2018-10-16 09:09:48 +0200 |
|---|---|---|
| committer | Boris Kolpackov <boris@codesynthesis.com> | 2018-10-16 09:09:48 +0200 |
| commit | 41ce54dea27dfc92bf0d2eb5c563c4abd5b57efa (patch) | |
| tree | a6daf97eb2a60f73e820f818fe283902c1608cfb | |
| parent | 11310002d0418984e2cafc6a867f8b010bd05314 (diff) | |
Fix bug in logical CPUs to sockets/cores/threads topology mapping
| -rw-r--r-- | bbot/agent/machine.cxx | 23 |
1 files changed, 14 insertions, 9 deletions
diff --git a/bbot/agent/machine.cxx b/bbot/agent/machine.cxx index af007ae..5ea5f1e 100644 --- a/bbot/agent/machine.cxx +++ b/bbot/agent/machine.cxx @@ -215,15 +215,20 @@ namespace bbot if (sizeof (sockaddr_un::sun_path) <= monitor.size ()) throw invalid_argument ("monitor unix socket path too long"); - // Map logical CPUs to sockets/cores/threads. Failed that, QEMU just makes - // it a machine with that number of sockets and some operating systems - // (like Windows) only can do two. + // Map logical CPUs to sockets/cores/threads keeping the number of and + // cores even. Failed that, QEMU just makes it a machine with that number + // of sockets and some operating systems (like Windows) can only do two. // - size_t cpu (ops.cpu ()); + // Note that for best results you may want to adjust (e.g., by over- + // committing) the number of CPUs to be power of 2. + // + size_t cpus (ops.cpu ()), cores (cpus); + + size_t sockets (cores >= 16 && cores % 4 == 0 ? 2 : + cores >= 64 && cores % 8 == 0 ? 4 : 1); + cores /= sockets; - size_t sockets (cpu <= 8 ? 1 : cpu <= 64 ? 2 : 4); - size_t cores (cpu / sockets); - size_t threads (cores <= 4 ? 1 : 2); + size_t threads (cores >= 8 && cores % 4 == 0 ? 2 : 1); cores /= threads; // We probably don't want to commit all the available RAM to the VM since @@ -231,7 +236,7 @@ namespace bbot // heuristics that we will use is 4G or 1G per CPU, whichever is greater // and the rest divide equally between the host and the VM. // - size_t ram ((cpu < 4 ? 4 : cpu) * 1024 * 1024); // Kb. + size_t ram ((cpus < 4 ? 4 : cpus) * 1024 * 1024); // Kb. if (ram > ops.ram ()) ram = ops.ram (); @@ -308,7 +313,7 @@ namespace bbot "-no-reboot", // Exit on VM reboot. "-m", to_string (ram / 1024) + "M", "-cpu", "host", - "-smp", (to_string (cpu) + + "-smp", (to_string (cpus) + ",sockets=" + to_string (sockets) + ",cores=" + to_string (cores) + ",threads=" + to_string (threads)), |