Update OS version requirements

roles/check_system_static/tasks/main.yml

@@ -13,8 +13,23 @@
 
 - name: Preflight check - Linux OS family and distribution version
   fail:
-    msg: "Red Hat Enterprise Linux/CentOS 6 is deprecated. Please use CentOS 7.3 and above. See https://github.com/pingcap/docs/blob/master/op-guide/recommendation.md"
-  when: "ansible_os_family == 'RedHat' and ansible_distribution_major_version == '6'"
+    msg: "System versions lower than Red Hat Enterprise Linux / CentOS 7.3 have been deprecated. Please use CentOS 7.3 and above. See https://github.com/pingcap/docs/blob/master/op-guide/recommendation.md"
+  when: "ansible_os_family == 'RedHat' and ansible_distribution_version < '7.3'"
+
+- name: Deploy epollexclusive script
+  copy: src="{{ script_dir }}/check/epollexclusive" dest="{{ deploy_dir }}/epollexclusive" mode=0755
+
+- name: Preflight check - Check if the operating system supports EPOLLEXCLUSIVE
+  shell: "{{ deploy_dir }}/epollexclusive"
+  register: epollexclusive_check
+
+- name: Clean epollexclusive script
+  file: path={{ deploy_dir }}/epollexclusive state=absent
+
+- name: Preflight check - Fail when epollexclusive is unavailable
+  fail:
+    msg: "The current machine may be a docker virtual machine, and the corresponding physical machine operating system does not support epollexclusive"
+  when: epollexclusive_check.stdout.find("True") == -1
 
 - name: Deploy check_cpufreq script
   copy: src="{{ script_dir }}/check/check_cpufreq.py" dest="{{ deploy_dir }}/check_cpufreq.py" mode=0755
@@ -29,7 +44,7 @@
 
 - name: Preflight check - Fail when CPU frequency governor is not set to performance mode
   fail:
-    msg: To achieve maximum performance, it is recommended to set The CPU frequency governor to performance mode, see https://github.com/pingcap/docs/blob/master/op-guide/ansible-deployment.md#step-7-configure-the-cpufreq-governor-mode-on-the-target-machine
+    msg: "To achieve maximum performance, it is recommended to set The CPU frequency governor to performance mode, see https://github.com/pingcap/docs/blob/master/op-guide/ansible-deployment.md#step-7-configure-the-cpufreq-governor-mode-on-the-target-machine"
   when:
     - cpufreq_available_governors.stdout.find("performance") != -1
     - cpufreq_current_governor.stdout.find("performance") == -1

scripts/check/epoll_chk.cc

@@ -0,0 +1,100 @@
+i/*
+ *
+ * Copyright 2017 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+#include <errno.h>
+#include <sys/eventfd.h>
+#include <sys/epoll.h>
+#include <unistd.h>
+#include <stdio.h>
+
+#ifndef EPOLLEXCLUSIVE
+#define EPOLLEXCLUSIVE (1 << 28)
+#endif
+
+/* This polling engine is only relevant on linux kernels supporting epoll() */
+bool grpc_is_epollexclusive_available(void) {
+  static bool logged_why_not = false;
+
+  int fd = epoll_create1(EPOLL_CLOEXEC);
+  if (fd < 0) {
+    if (!logged_why_not) {
+      printf(
+              "epoll_create1 failed with error: %d. Not using epollex polling "
+              "engine.",
+              fd);
+      logged_why_not = true;
+    }
+    return false;
+  }
+  int evfd = eventfd(0, EFD_NONBLOCK | EFD_CLOEXEC);
+  if (evfd < 0) {
+    if (!logged_why_not) {
+      printf(
+              "eventfd failed with error: %d. Not using epollex polling "
+              "engine.",
+              fd);
+      logged_why_not = true;
+    }
+    close(fd);
+    return false;
+  }
+  struct epoll_event ev;
+  /* choose events that should cause an error on
+     EPOLLEXCLUSIVE enabled kernels - specifically the combination of
+     EPOLLONESHOT and EPOLLEXCLUSIVE */
+  ev.events = (uint32_t)(EPOLLET | EPOLLIN | EPOLLEXCLUSIVE | EPOLLONESHOT);
+  ev.data.ptr = NULL;
+  if (epoll_ctl(fd, EPOLL_CTL_ADD, evfd, &ev) != 0) {
+    if (errno != EINVAL) {
+      if (!logged_why_not) {
+        printf(
+            "epoll_ctl with EPOLLEXCLUSIVE | EPOLLONESHOT failed with error: "
+            "%d. Not using epollex polling engine.",
+            errno);
+        logged_why_not = true;
+      }
+      close(fd);
+      close(evfd);
+      return false;
+    }
+  } else {
+    if (!logged_why_not) {
+      printf(
+              "epoll_ctl with EPOLLEXCLUSIVE | EPOLLONESHOT succeeded. This is "
+              "evidence of no EPOLLEXCLUSIVE support. Not using "
+              "epollex polling engine.");
+      logged_why_not = true;
+    }
+    close(fd);
+    close(evfd);
+    return false;
+  }
+  close(evfd);
+  close(fd);
+  return true;
+}
+
+int main() {
+    if (grpc_is_epollexclusive_available()) {
+        printf("True: epollexclusive is available\n");
+        return 0;
+    } else {
+        printf("False: epollexclusive is NOT available\n");
+        return 1;
+    }
+}