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FROMLIST: dma-buf: rk_system_heap: avoid reclaim for order 4

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Using order 4 pages would be helpful for IOMMUs mapping, but trying to
get order 4 pages could spend quite much time in the page allocation.
From the perspective of responsiveness, the deterministic memory
allocation speed, I think, is quite important.

The order 4 allocation with __GFP_RECLAIM may spend much time in
reclaim and compation logic. __GFP_NORETRY also may affect. These cause
unpredictable delay.

To get reasonable allocation speed from dma-buf system heap, use
HIGH_ORDER_GFP for order 4 to avoid reclaim. And let me remove
meaningless __GFP_COMP for order 0.

According to my tests, order 4 with MID_ORDER_GFP could get more number
of order 4 pages but the elapsed times could be very slow.

         time	order 8	order 4	order 0
     584 usec	0	160	0
  28,428 usec	0	160	0
 100,701 usec	0	160	0
  76,645 usec	0	160	0
  25,522 usec	0	160	0
  38,798 usec	0	160	0
  89,012 usec	0	160	0
  23,015 usec	0	160	0
  73,360 usec	0	160	0
  76,953 usec	0	160	0
  31,492 usec	0	160	0
  75,889 usec	0	160	0
  84,551 usec	0	160	0
  84,352 usec	0	160	0
  57,103 usec	0	160	0
  93,452 usec	0	160	0

If HIGH_ORDER_GFP is used for order 4, the number of order 4 could be
decreased but the elapsed time results were quite stable and fast
enough.

         time	order 8	order 4	order 0
   1,356 usec	0	155	80
   1,901 usec	0	11	2384
   1,912 usec	0	0	2560
   1,911 usec	0	0	2560
   1,884 usec	0	0	2560
   1,577 usec	0	0	2560
   1,366 usec	0	0	2560
   1,711 usec	0	0	2560
   1,635 usec	0	28	2112
     544 usec	10	0	0
     633 usec	2	128	0
     848 usec	0	160	0
     729 usec	0	160	0
   1,000 usec	0	160	0
   1,358 usec	0	160	0
   2,638 usec	0	31	2064

Signed-off-by: Jaewon Kim <jaewon31.kim@samsung.com>
Reviewed-by: John Stultz <jstultz@google.com>

Link: https://patchwork.kernel.org/project/linux-mm/patch/20230303050332.10138-1-jaewon31.kim@samsung.com/

Signed-off-by: Jianqun Xu <jay.xu@rock-chips.com>
Change-Id: I352021b68684ea33e4538a8beda9399fed1d1d79
This commit is contained in:
Jianqun Xu
2023-03-03 15:52:41 +08:00
committed by Tao Huang
parent fd087b355c
commit 71d818ec98
1 changed files with 2 additions and 3 deletions
Download Patch File Download Diff File Expand all files Collapse all files
drivers/dma-buf/heaps/rk_system_heap.c
+2 -3
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@@ -58,12 +58,11 @@ struct dma_heap_attachment {
bool uncached;
};
#define LOW_ORDER_GFP (GFP_HIGHUSER | __GFP_ZERO | __GFP_COMP)
#define MID_ORDER_GFP (LOW_ORDER_GFP | __GFP_NOWARN)
#define LOW_ORDER_GFP (GFP_HIGHUSER | __GFP_ZERO)
#define HIGH_ORDER_GFP (((GFP_HIGHUSER | __GFP_ZERO | __GFP_NOWARN \
| __GFP_NORETRY) & ~__GFP_RECLAIM) \
| __GFP_COMP)
static gfp_t order_flags[] = {HIGH_ORDER_GFP, MID_ORDER_GFP, LOW_ORDER_GFP};
static gfp_t order_flags[] = {HIGH_ORDER_GFP, HIGH_ORDER_GFP, LOW_ORDER_GFP};
/*
* The selection of the orders used for allocation (1MB, 64K, 4K) is designed
* to match with the sizes often found in IOMMUs. Using order 4 pages instead