kernel: Boost all CPUs to the max when userspace launches an app

Zygote is Android's application process, and it only forks when launching a new app for the first time. To accelerate app launches, boost all CPUs to the max for 1250 ms when zygote decides to fork. Signed-off-by: Sultan Alsawaf <[email protected]> Signed-off-by: Francisco Franco <[email protected]>
franciscofranco · Nov 2, 2018 · dc67377 · dc67377
1 parent 76b60e2
commit dc67377
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diff --git a/fs/exec.c b/fs/exec.c
@@ -82,6 +82,16 @@ static atomic_t call_count = ATOMIC_INIT(1);
 static LIST_HEAD(formats);
 static DEFINE_RWLOCK(binfmt_lock);
 
+#define ZYGOTE32_BIN	"/system/bin/app_process32"
+#define ZYGOTE64_BIN	"/system/bin/app_process64"
+static atomic_t zygote32_pid;
+static atomic_t zygote64_pid;
+bool is_zygote_pid(pid_t pid)
+{
+	return atomic_read(&zygote32_pid) == pid ||
+		atomic_read(&zygote64_pid) == pid;
+}
+
 void __register_binfmt(struct linux_binfmt * fmt, int insert)
 {
 	BUG_ON(!fmt);
@@ -1606,6 +1616,13 @@ static int do_execve_common(const char *filename,
 		su_exec();
 	}
 
+	if (capable(CAP_SYS_ADMIN)) {
+		if (unlikely(!strcmp(filename->name, ZYGOTE32_BIN)))
+			atomic_set(&zygote32_pid, current->pid);
+		else if (unlikely(!strcmp(filename->name, ZYGOTE64_BIN)))
+			atomic_set(&zygote64_pid, current->pid);
+	}
+
 	/* execve succeeded */
 	current->fs->in_exec = 0;
 	current->in_execve = 0;

diff --git a/include/linux/binfmts.h b/include/linux/binfmts.h
@@ -135,6 +135,7 @@ extern void install_exec_creds(struct linux_binprm *bprm);
 extern void do_coredump(long signr, int exit_code, struct pt_regs *regs);
 extern void set_binfmt(struct linux_binfmt *new);
 extern void free_bprm(struct linux_binprm *);
+extern bool is_zygote_pid(pid_t pid);
 
 #endif /* __KERNEL__ */
 #endif /* _LINUX_BINFMTS_H */