GitHub user hbdeshmukh opened a pull request:
https://github.com/apache/incubator-quickstep/pull/126
QUICKSTEP-41 Automatically pin workers to CPU cores
- Automatically pin worker threads to CPU cores.
- Use auto pinning when either there are no affinities provided, or the
provided affinities are incorrect.
- Try to balance CPU cores across multiple sockets, when maximum
parallelism is not used.
Shown below is a demonstration of this PR in action.
```
$ numactl --hardware
available: 2 nodes (0-1)
node 0 cpus: 0 1 2 3 4 5 12 13 14 15 16 17
node 1 cpus: 6 7 8 9 10 11 18 19 20 21 22 23
```
The machine has 2 NUMA sockets and 24 CPUs, with 12 CPUS on each NUMA
socket. Next we run Quickstep without any hints on number of workers and their
affinities.
```
$ GLOG_v=1 GLOG_logtostderr=1 ./quickstep_cli_shell
Quickstep expects at least one worker thread, switching to the default
number of worker threads
Starting Quickstep with 24 worker thread(s) and a 21.97 GB buffer pool
Empty worker affinities provided, switching to default worker affinities
Affinities: 0, 6, 1, 7, 2, 8, 3, 9, 4, 10, 5, 11, 12, 18, 13, 19, 14, 20,
15, 21, 16, 22, 17, 23
```
```
$ GLOG_v=1 GLOG_logtostderr=1 ./quickstep_cli_shell -num_workers=24
Starting Quickstep with 24 worker thread(s) and a 21.97 GB buffer pool
Empty worker affinities provided, switching to default worker affinities
Affinities: 0, 6, 1, 7, 2, 8, 3, 9, 4, 10, 5, 11, 12, 18, 13, 19, 14, 20,
15, 21, 16, 22, 17, 23
$ GLOG_v=1 GLOG_logtostderr=1 ./quickstep_cli_shell -num_workers=2
Starting Quickstep with 2 worker thread(s) and a 21.97 GB buffer pool
Empty worker affinities provided, switching to default worker affinities
Affinities: 0, 6
$ GLOG_v=1 GLOG_logtostderr=1 ./quickstep_cli_shell -num_workers=5
Starting Quickstep with 5 worker thread(s) and a 21.97 GB buffer pool
Empty worker affinities provided, switching to default worker affinities
Affinities: 0, 6, 1, 7, 2
```
Right now we don't over-subscribe worker threads to CPU cores. If there are
more workers than the affinities (not recommended anyway), extra workers are
not affinitized to any CPU core.
```
$ GLOG_v=1 GLOG_logtostderr=1 ./quickstep_cli_shell -num_workers=25
Starting Quickstep with 25 worker thread(s) and a 21.97 GB buffer pool
Empty worker affinities provided, switching to default worker affinities
--num_workers is 25, but only specified 24 CPU affinities with
--worker_affinities. 1 workers will be unaffinitized.
Affinities: 0, 6, 1, 7, 2, 8, 3, 9, 4, 10, 5, 11, 12, 18, 13, 19, 14, 20,
15, 21, 16, 22, 17, 23, -1
```
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/apache/incubator-quickstep auto-worker-pinning
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/incubator-quickstep/pull/126.patch
To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:
This closes #126
----
commit 248cec27341fa8f19658d0705c1dca3fec0ff550
Author: Harshad Deshmukh <[email protected]>
Date: 2016-11-04T04:34:37Z
Auto pin workers to CPU cores
- Automatically pin worker threads to CPU cores.
- Use auto pinning when either there are no affinities provided, or the
provided affinities are incorrect.
- Try to balance CPU cores across multiple sockets, when maximum
paralellism is not used.
----
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