tune grpc connection count between tidb and tikv

[zhangjinpeng87]

Signed-off-by: zhangjinpeng1987 zhangjinpeng@pingcap.com

What problem does this PR solve?

Tune the gRPC connection between TiDB and TiKV to make super batch works better. This is a prepare step of tikv/tikv#5598, this pr will make tikv/tikv#5598 works better.

What is changed and how it works?

Tune the default gRPC connection between tidb and tikv.

Check List

Tests

• Unit test

[zhangjinpeng87]

/bench

[sre-bot]

@@                               Benchmark Diff                               @@
================================================================================
--- tidb: 076503a4683f91e40ec8f1c14119ed532e6fda63
+++ tidb: 738da0ed2148fad3b34309f0aeebd78f7d30583e
tikv: 453e866835d654e20ae4d01fe75ba17abf8577f9
pd: 752ecd784fabfe1841a252be29c01284de8098f6
================================================================================
oltp_update_non_index:
    * QPS: 4844.92 ± 0.46% (std=13.94) delta: -0.39% (p=0.187)
    * Latency p50: 26.42 ± 0.46% (std=0.07) delta: 0.38%
    * Latency p99: 44.60 ± 4.56% (std=1.45) delta: 4.66%
            
oltp_insert:
    * QPS: 4687.65 ± 0.18% (std=6.10) delta: -0.04% (p=0.853)
    * Latency p50: 27.30 ± 0.18% (std=0.04) delta: 0.04%
    * Latency p99: 50.34 ± 2.24% (std=0.75) delta: -0.74%
            
oltp_read_write:
    * QPS: 15115.50 ± 0.05% (std=5.61) delta: 0.23% (p=0.878)
    * Latency p50: 169.73 ± 0.06% (std=0.08) delta: -0.19%
    * Latency p99: 320.17 ± 0.00% (std=0.00) delta: -1.78%
            
oltp_update_index:
    * QPS: 4334.35 ± 0.53% (std=13.56) delta: 0.36% (p=0.144)
    * Latency p50: 29.47 ± 0.07% (std=0.01) delta: -0.44%
    * Latency p99: 56.08 ± 2.23% (std=0.83) delta: -3.14%
            

[codecov]

Codecov Report

Merging #12884 into master will increase coverage by 0.0074%.
The diff coverage is n/a.

@@               Coverage Diff                @@
##             master     #12884        +/-   ##
================================================
+ Coverage   79.9822%   79.9897%   +0.0074%     
================================================
  Files           465        465                
  Lines        107255     106940       -315     
================================================
- Hits          85785      85541       -244     
+ Misses        15028      14960        -68     
+ Partials       6442       6439         -3

[tabokie]

/bench

tidb.yml:
  tikv_client:
    # Max gRPC connections that will be established with each tikv-server.
    grpc-connection-count: 4

[sre-bot]

@@                               Benchmark Diff                               @@
================================================================================
--- tidb: 5ea98344c482f325847a5c1e2ba0daf1759c1600
+++ tidb: 738da0ed2148fad3b34309f0aeebd78f7d30583e
tikv: 453e866835d654e20ae4d01fe75ba17abf8577f9
pd: 1af456e3b493dc1e9de5ef85ab7595909b4d9796
================================================================================
oltp_update_non_index:
    * QPS: 4866.21 ± 0.41% (std=12.26) delta: 0.31% (p=0.225)
    * Latency p50: 26.30 ± 0.41% (std=0.07) delta: -0.31%
    * Latency p99: 42.05 ± 3.19% (std=0.99) delta: -3.13%
            
oltp_insert:
    * QPS: 4686.11 ± 0.39% (std=12.92) delta: 0.20% (p=0.383)
    * Latency p50: 27.31 ± 0.37% (std=0.07) delta: -0.20%
    * Latency p99: 50.11 ± 0.00% (std=0.00) delta: -1.35%
            
oltp_point_select:
    * QPS: 35341.56 ± 0.89% (std=216.30) delta: 6.83% (p=0.105)
    * Latency p50: 3.62 ± 0.90% (std=0.02) delta: -6.31%
    * Latency p99: 12.75 ± 1.80% (std=0.16) delta: -1.39%