[TOC]

## 無分類

- [高效能取向kernel boot args](/0RaVqoHmTu24Zypbo7uaXw)

## Lockfree

相關文章

- [RCU](/SRoLfUUlR72wFpESj_BLrA)

## 低延遲

### 相關文章

#### Linux Kernel / NIC

- [Low Latency Performance Tuning for
Red Hat Enterprise Linux 7](https://access.redhat.com/sites/default/files/attachments/201501-perf-brief-low-latency-tuning-rhel7-v2.1.pdf)

#### C++

- [Optimization Subtleties Using C++ in Low-Latency
Trading.](https://finance.jaxlondon.com/wp-content/uploads/2016/05/Optimization-Subtleties-Using-C-in-Low-Latency_Jason-Hearne-McGuiness.pdf)

### TCP stack

- [Introducing TCPDirect](https://stacresearch.com/system/files/resource/files/STAC-Summit-7-November-2016-Solarflare.pdf)

由於DPDK只有做到L3，如果需要L4 (TCP/UDP)需要額外的stack：

- Mellanox/libvma
- socketxtreme
- solarflare
- Onload
- TCPDirect
- seastar
- F-Stack
- mTCP

### 文獻研究

- [Low Latency C++ for Fun and Profit](/BiMNtdmoT6KRG55G9CJRCw)

## 指令

### flamegraph

./perf record -a -g -F 2599 -p 451 sleep 30
./perf script -i perf.data > p1
./stackcollapse-perf.pl p1 &> perf.folder
./flamegraph.pl perf.folder > perf.svg

### mysql - 建user取得權限

create user 'user'@'%' identified by 'pass';
GRANT ALL PRIVILEGES ON `db`.* TO 'user'@'%';
FLUSH PRIVILEGES;

### postgres - 修復seq

SELECT 'SELECT SETVAL(' ||
       quote_literal(quote_ident(PGT.schemaname) || '.' || quote_ident(S.relname)) ||
       ', COALESCE(MAX(' ||quote_ident(C.attname)|| '), 1) ) FROM ' ||
       quote_ident(PGT.schemaname)|| '.'||quote_ident(T.relname)|| ';'
FROM pg_class AS S,
     pg_depend AS D,
     pg_class AS T,
     pg_attribute AS C,
     pg_tables AS PGT
WHERE S.relkind = 'S'
    AND S.oid = D.objid
    AND D.refobjid = T.oid
    AND D.refobjid = C.attrelid
    AND D.refobjsubid = C.attnum
    AND T.relname = PGT.tablename
ORDER BY S.relname;

### TiDB created_at

ALTER TABLE `Orders`  ADD `created_at` DATETIME(6) NOT NULL DEFAULT CURRENT_TIMESTAMP(6)

### k8s 檢查沒有crash pod

kubectl get pod -A |grep -Pv '\s+([1-9]+)\/\1\s+'

### netlink 設定 macvlan

worker2 ~ # ip link add link enp1s0np0 mac1 type macvlan
worker2 ~ # ip addr add 10.168.27.90/24 dev mac1
worker2 ~ # ip link set mac1 up
worker2 ~ # ip route add 172.22.20.0/24 dev mac1 via 10.168.27.254

### cri-o 設定 mirror

cat << EOF > /etc/containers/registries.conf
unqualified-search-registries = []

[[registry]]
  prefix = "docker.io"
  location = "docker.io"

  [[registry.mirror]]
    insecure = true
    location = "10.168.98.31:35001"
  [[registry.mirror]]
    insecure = true
    location = "10.168.98.32:35001"

[[registry]]
  prefix = "k8s.gcr.io"
  location = "k8s.gcr.io"

  [[registry.mirror]]
    insecure = true
    location = "10.168.98.31:35002"
  [[registry.mirror]]
    insecure = true
    location = "10.168.98.32:35002"

EOF
systemctl reload crio

### TiDB 建議的 kubernetes kernel tuning參數

cat <<EOF >  /etc/sysctl.d/k8s.conf
net.bridge.bridge-nf-call-ip6tables = 1
net.bridge.bridge-nf-call-iptables = 1
net.bridge.bridge-nf-call-arptables = 1
net.core.somaxconn = 32768
vm.swappiness = 0
net.ipv4.tcp_syncookies = 0
net.ipv4.ip_forward = 1
fs.file-max = 1000000
fs.inotify.max_user_watches = 1048576
fs.inotify.max_user_instances = 1024
net.ipv4.conf.all.rp_filter = 1
net.ipv4.neigh.default.gc_thresh1 = 80000
net.ipv4.neigh.default.gc_thresh2 = 90000
net.ipv4.neigh.default.gc_thresh3 = 100000
EOF

cat <<EOF >>  /etc/security/limits.conf
root        soft        nofile        1048576
root        hard        nofile        1048576
root        soft        stack         10240
EOF

sysctl --system

### 清除 docker images

docker image prune -a --filter "until=720h"

### kubernetes init container

initContainers:
- name: setup-net
  image: docker.io/alpine:3.14
  command:
  - ash
  - -ec
  - |
    ip addr flush dev net1 scope global
    ip addr add 10.101.62.98/27 dev net1
  securityContext:
    capabilities:
      add: ["NET_ADMIN"]

### evans cli mode

echo '{}' | evans -p 4037 --host colo --proto QuoteService.proto cli call quote.Quote.AvailableOptions QuoteService.proto > /tmp/options.json

### socat 挖洞轉發TCP連線

socat tcp-listen:8001,reuseaddr,fork tcp:localhost:8000