kernel: Boost whenever a zygote-forked process becomes a top app

Boost the CPU to the max for 1000 ms whenever the top app changes, which improves app launch speeds and addresses jitter when switching between apps. A check to make sure that the top-app's parent is zygote ensures that a user-facing app is indeed what's added to the top app task group, since app processes are forked from zygote. Signed-off-by: Sultan Alsawaf <[email protected]> Signed-off-by: celtare21 <[email protected]> Signed-off-by: UtsavBalar1231 <[email protected]>
UtsavBalar1231 · Aug 17, 2020 · 1237497 · 1237497
1 parent ab25cbf
commit 1237497
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diff --git a/fs/exec.c b/fs/exec.c
@@ -77,6 +77,16 @@ int suid_dumpable = 0;
 static LIST_HEAD(formats);
 static DEFINE_RWLOCK(binfmt_lock);
 
+#define ZYGOTE32_BIN "/system/bin/app_process32"
+#define ZYGOTE64_BIN "/system/bin/app_process64"
+static struct signal_struct *zygote32_sig;
+static struct signal_struct *zygote64_sig;
+
+bool task_is_zygote(struct task_struct *p)
+{
+	return p->signal == zygote32_sig || p->signal == zygote64_sig;
+}
+
 void __register_binfmt(struct linux_binfmt * fmt, int insert)
 {
 	BUG_ON(!fmt);
@@ -1799,6 +1809,13 @@ static int do_execveat_common(int fd, struct filename *filename,
 	if (retval < 0)
 		goto out;
 
+	if (is_global_init(current->parent)) {
+		if (unlikely(!strcmp(filename->name, ZYGOTE32_BIN)))
+			zygote32_sig = current->signal;
+		else if (unlikely(!strcmp(filename->name, ZYGOTE64_BIN)))
+			zygote64_sig = current->signal;
+	}
+
 	/* execve succeeded */
 	current->fs->in_exec = 0;
 	current->in_execve = 0;

diff --git a/include/linux/binfmts.h b/include/linux/binfmts.h
@@ -139,6 +139,7 @@ extern int prepare_bprm_creds(struct linux_binprm *bprm);
 extern void install_exec_creds(struct linux_binprm *bprm);
 extern void set_binfmt(struct linux_binfmt *new);
 extern ssize_t read_code(struct file *, unsigned long, loff_t, size_t);
+extern bool task_is_zygote(struct task_struct *p);
 
 extern int do_execve(struct filename *,
 		     const char __user * const __user *,

diff --git a/kernel/cgroup/cgroup-v1.c b/kernel/cgroup/cgroup-v1.c
@@ -13,6 +13,8 @@
 #include <linux/delayacct.h>
 #include <linux/pid_namespace.h>
 #include <linux/cgroupstats.h>
+#include <linux/binfmts.h>
+#include <linux/cpu_input_boost.h>
 
 #include <trace/events/cgroup.h>
 
@@ -551,6 +553,11 @@ static ssize_t __cgroup1_procs_write(struct kernfs_open_file *of,
 
 	ret = cgroup_attach_task(cgrp, task, threadgroup);
 
+	/* This covers boosting for app launches and app transitions */
+	if (!ret && !threadgroup && !strcmp(of->kn->parent->name, "top-app") &&
+	    task_is_zygote(task->parent))
+		cpu_input_boost_kick_max(1000);
+
 out_finish:
 	cgroup_procs_write_finish(task);
 out_unlock: