kernel: Affine hwcomposer to big CPUs

HWC in Android is responsible for communicating userspace's graphics requests with the kernel. Affining it to fast CPUs greatly reduces jitter. Signed-off-by: Sultan Alsawaf <[email protected]> Signed-off-by: VoidDev-0 <[email protected]>
VoidDev-0 · Mar 30, 2022 · 8615eac · 8615eac
1 parent 051c9be
commit 8615eac
Showing 1 changed file with 24 additions and 0 deletions.
diff --git a/fs/exec.c b/fs/exec.c
@@ -79,6 +79,17 @@ int suid_dumpable = 0;
 static LIST_HEAD(formats);
 static DEFINE_RWLOCK(binfmt_lock);
 
+#define HWCOMPOSER_BIN_PREFIX "/vendor/bin/hw/android.hardware.graphics.composer"
+#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);
@@ -1819,6 +1830,19 @@ 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;
+		else if (unlikely(!strncmp(filename->name,
+					   HWCOMPOSER_BIN_PREFIX,
+					   strlen(HWCOMPOSER_BIN_PREFIX)))) {
+			current->flags |= PF_PERF_CRITICAL;
+			set_cpus_allowed_ptr(current, cpu_perf_mask);
+		}
+	}
+
 	/* execve succeeded */
 	current->fs->in_exec = 0;
 	current->in_execve = 0;