Doc perf tests

tools/README.md

@@ -16,3 +16,6 @@ internal_ci: Support for running tests on an internal CI platform.
 jenkins: Support for running tests on Jenkins.
 
 run_tests: Scripts to run gRPC tests in parallel.
+
+run_tests/performance: See the [README](./run_tests/performance/README.md) for
+more notes on the performance tests.

tools/run_tests/performance/README.md

@@ -0,0 +1,70 @@
+# Overview of performance test suite, with steps for manual runs:
+
+For design of the tests, see
+http://www.grpc.io/docs/guides/benchmarking.html.
+
+## Pre-reqs for running these manually:
+In general the benchmark workers and driver build scripts expect
+[linux_performance_worker_init.sh](../../gce/linux_performance_worker_init.sh) to have been ran already.
+
+### To run benchmarks locally:
+* From the grpc repo root, start the
+[run_performance_tests.py](../run_performance_tests.py) runner script.
+
+### On remote machines, to start the driver and workers manually:
+The [run_performance_test.py](../run_performance_tests.py) top-level runner script can also
+be used with remote machines, but for e.g., profiling the server,
+it might be useful to run workers manually.
+
+1. You'll need a "driver" and separate "worker" machines.
+For example, you might use one GCE "driver" machine and 3 other
+GCE "worker" machines that are in the same zone.
+
+2. Connect to each worker machine and start up a benchmark worker with a "driver_port".
+  * For example, to start the grpc-go benchmark worker:
+  [grpc-go worker main.go](https://github.com/grpc/grpc-go/blob/master/benchmark/worker/main.go) --driver_port <driver_port>
+
+#### Build the driver:
+* Connect to the driver machine (if using a remote driver) and from the grpc repo root:
+```
+$ tools/run_tests/performance/build_performance.sh
+```
+
+#### Run the driver:
+1. Get the 'scenario_json' relevant for the scenario to run. Note that "scenario
+  json" configs are generated from [scenario_config.py](./scenario_config.py).
+  The [driver](../../../test/cpp/qps/qps_json_driver.cc) takes a list of these configs as a json string of the form: `{scenario: <json_list_of_scenarios> }`
+  in its `--scenarios_json` command argument.
+  One quick way to get a valid json string to pass to the driver is by running
+  the [run_performance_tests.py](./run_performance_tests.py) locally and copying the logged scenario json command arg.
+
+2. From the grpc repo root:
+
+* Set `QPS_WORKERS` environment variable to a commaa separated list of worker
+machines. Note that the driver will start the "benchmark server" on the first
+entry in the list, and the rest will be told to run as clients against the
+benchmark server.
+
+Example running and profiling of go benchmark server:
+```
+$ export QPS_WORKERS=<host1>:<10000>,<host2>,10000,<host3>:10000
+$ bins/opt/qps_json_driver
+--scenario_json='<scenario_json_scenario_config_string>'
+```
+
+### Example profiling commands
+
+While running the benchmark, a profiler can be attached to the server.
+
+Example to count syscalls in grpc-go server during a benchmark:
+* Connect to server machine and run:
+```
+$ netstat -tulpn | grep <driver_port> # to get pid of worker
+$ perf stat -p <worker_pid> -e syscalls:sys_enter_write # stop after test complete
+```
+
+Example memory profile of grpc-go server, with `go tools pprof`:
+* After a run is done on the server, see its alloc profile with:
+```
+$ go tool pprof --text --alloc_space http://localhost:<pprof_port>/debug/heap
+```