ANDROID: vendor hooks: skip mem reclaim throttle to speed up mem alloc

Allowing certain important threads to skip waiting and direct mem
reclaim, speeding up mem allocation for critical processes.

Bug: 411514531

Change-Id: I56506249bb5eda705185476c71eb4b9c7e3a3a55
Signed-off-by: Qianfeng Rong <rongqianfeng@vivo.corp-partner.google.com>

drivers/android/vendor_hooks.c

@@ -478,6 +478,7 @@ EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_direct_reclaim_end);
 EXPORT_TRACEPOINT_SYMBOL_GPL(android_rvh_do_read_fault);
 EXPORT_TRACEPOINT_SYMBOL_GPL(android_rvh_alloc_pages_reclaim_start);
 EXPORT_TRACEPOINT_SYMBOL_GPL(android_rvh_alloc_pages_reclaim_cycle_end);
+EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_throttle_direct_reclaim_bypass);
 EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_bd_link_disk_holder);
 EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_binder_new_ref);
 EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_binder_del_ref);

include/trace/hooks/vmscan.h

@@ -98,6 +98,9 @@ DECLARE_HOOK(android_vh_direct_reclaim_begin,
 DECLARE_HOOK(android_vh_direct_reclaim_end,
 	TP_PROTO(int prio),
 	TP_ARGS(prio));
+DECLARE_HOOK(android_vh_throttle_direct_reclaim_bypass,
+	TP_PROTO(bool *bypass),
+	TP_ARGS(bypass));
 
 #endif /* _TRACE_HOOK_VMSCAN_H */
 /* This part must be outside protection */

mm/vmscan.c

@@ -6574,6 +6574,7 @@ static bool throttle_direct_reclaim(gfp_t gfp_mask, struct zonelist *zonelist,
 	struct zoneref *z;
 	struct zone *zone;
 	pg_data_t *pgdat = NULL;
+	bool bypass = false;
 
 	/*
 	 * Kernel threads should not be throttled as they may be indirectly
@@ -6622,6 +6623,10 @@ static bool throttle_direct_reclaim(gfp_t gfp_mask, struct zonelist *zonelist,
 	if (!pgdat)
 		goto out;
 
+	trace_android_vh_throttle_direct_reclaim_bypass(&bypass);
+	if (bypass)
+		goto out;
+
 	/* Account for the throttling */
 	count_vm_event(PGSCAN_DIRECT_THROTTLE);