| # Copyright 2013 The Chromium Authors. All rights reserved. |
| # Use of this source code is governed by a BSD-style license that can be |
| # found in the LICENSE file. |
| |
| """ |
| Utility functions used to generate info used by the bots. |
| |
| TODO(eyaich): Remove once we no longer generate the list of benchmarks to |
| run on the perf waterfall in telemetry. |
| """ |
| |
| import hashlib |
| |
| def GetDeviceAffinity(num_shards, base_name): |
| # Based on the current timings, we shift the result of the hash function to |
| # achieve better load balancing. Those shift values are to be revised when |
| # necessary. The shift value is calculated such that the total cycle time |
| # is minimized. |
| hash_shift = { |
| 2 : 47, # for old desktop configurations with 2 slaves |
| 5 : 56, # for new desktop configurations with 5 slaves |
| 21 : 43 # for Android 3 slaves 7 devices configurations |
| } |
| shift = hash_shift.get(num_shards, 0) |
| base_name_hash = hashlib.sha1(base_name).hexdigest() |
| device_affinity = (int(base_name_hash, 16) >> shift) % num_shards |
| return device_affinity |
