sched: disable sched_autogroup by default

hulk inclusion
category: performance
bugzilla: 32059, https://gitee.com/openeuler/kernel/issues/I65DOZ
CVE: NA

--------------------------------

This option optimizes the scheduler for common desktop workloads by
automatically creating and populating task groups.  This separation
of workloads isolates aggressive CPU burners (like build jobs) from
desktop applications.  Task group autogeneration is currently based
upon task session.

We do not need this for mostly server workloads, so just disable by
default. If you need this feature really, just enable it by sysctl:

sysctl -w kernel.sched_autogroup_enabled=1
Signed-off-by: NJialin Zhang <zhangjialin11@huawei.com>
Reviewed-by: NXie XiuQi <xiexiuqi@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

kernel/sched/autogroup.c

@@ -5,7 +5,7 @@
 #include <linux/nospec.h>
 #include "sched.h"
 
-unsigned int __read_mostly sysctl_sched_autogroup_enabled = 1;
+unsigned int __read_mostly sysctl_sched_autogroup_enabled;
 static struct autogroup autogroup_default;
 static atomic_t autogroup_seq_nr;