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* [PATCH v2] dma-buf: system_heap: avoid reclaim for order 4
       [not found] <CGME20230210045651epcas1p1392354722c8ad6d4ffad6f934ba78742@epcas1p1.samsung.com>
@ 2023-02-10  4:56 ` Jaewon Kim
       [not found]   ` <CGME20230210045651epcas1p1392354722c8ad6d4ffad6f934ba78742@epcms1p7>
  0 siblings, 1 reply; 3+ messages in thread
From: Jaewon Kim @ 2023-02-10  4:56 UTC (permalink / raw)
  To: john.stultz, tjmercier, sumit.semwal, daniel.vetter, akpm,
	hannes, mhocko
  Cc: linux-mm, linux-kernel, jaewon31.kim, Jaewon Kim

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>
---
 drivers/dma-buf/heaps/system_heap.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/dma-buf/heaps/system_heap.c b/drivers/dma-buf/heaps/system_heap.c
index e8bd10e60998..920db302a273 100644
--- a/drivers/dma-buf/heaps/system_heap.c
+++ b/drivers/dma-buf/heaps/system_heap.c
@@ -41,12 +41,11 @@ struct dma_heap_attachment {
 	bool mapped;
 };
 
-#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
-- 
2.17.1


^ permalink raw reply related	[flat|nested] 3+ messages in thread
* Re: [PATCH v2] dma-buf: system_heap: avoid reclaim for order 4
       [not found]   ` <CGME20230210045651epcas1p1392354722c8ad6d4ffad6f934ba78742@epcms1p7>
@ 2023-02-10  5:03     ` Jaewon Kim
  2023-02-14 22:25       ` John Stultz
  0 siblings, 1 reply; 3+ messages in thread
From: Jaewon Kim @ 2023-02-10  5:03 UTC (permalink / raw)
  To: Jaewon Kim, jstultz, tjmercier, sumit.semwal, daniel.vetter,
	akpm, hannes, mhocko
  Cc: linux-mm, linux-kernel, jaewon31.kim

>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>
>---
> drivers/dma-buf/heaps/system_heap.c | 5 ++---
> 1 file changed, 2 insertions(+), 3 deletions(-)
>
>diff --git a/drivers/dma-buf/heaps/system_heap.c b/drivers/dma-buf/heaps/system_heap.c
>index e8bd10e60998..920db302a273 100644
>--- a/drivers/dma-buf/heaps/system_heap.c
>+++ b/drivers/dma-buf/heaps/system_heap.c
>@@ -41,12 +41,11 @@ struct dma_heap_attachment {
> 	bool mapped;
> };
> 
>-#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
>--
>2.17.1
>
>

added John Stultz <jstultz@google.com>

^ permalink raw reply	[flat|nested] 3+ messages in thread
* Re: [PATCH v2] dma-buf: system_heap: avoid reclaim for order 4
  2023-02-10  5:03     ` Jaewon Kim
@ 2023-02-14 22:25       ` John Stultz
  0 siblings, 0 replies; 3+ messages in thread
From: John Stultz @ 2023-02-14 22:25 UTC (permalink / raw)
  To: jaewon31.kim
  Cc: tjmercier, sumit.semwal, daniel.vetter, akpm, hannes, mhocko,
	linux-mm, linux-kernel, jaewon31.kim

On Thu, Feb 9, 2023 at 9:03 PM Jaewon Kim <jaewon31.kim@samsung.com> wrote:
>
> >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>
> >---
> > drivers/dma-buf/heaps/system_heap.c | 5 ++---
> > 1 file changed, 2 insertions(+), 3 deletions(-)
> >
> >diff --git a/drivers/dma-buf/heaps/system_heap.c b/drivers/dma-buf/heaps/system_heap.c
> >index e8bd10e60998..920db302a273 100644
> >--- a/drivers/dma-buf/heaps/system_heap.c
> >+++ b/drivers/dma-buf/heaps/system_heap.c
> >@@ -41,12 +41,11 @@ struct dma_heap_attachment {
> >       bool mapped;
> > };
> >
> >-#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
> >--
> >2.17.1
> >
> >
>
> added John Stultz <jstultz@google.com>

Sorry for the delay!
Reviewed-by: John Stultz <jstultz@google.com>

thanks
-john

^ permalink raw reply	[flat|nested] 3+ messages in thread
end of thread, other threads:[~2023-02-14 22:25 UTC | newest]

Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
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     [not found] <CGME20230210045651epcas1p1392354722c8ad6d4ffad6f934ba78742@epcas1p1.samsung.com>
2023-02-10  4:56 ` [PATCH v2] dma-buf: system_heap: avoid reclaim for order 4 Jaewon Kim
     [not found]   ` <CGME20230210045651epcas1p1392354722c8ad6d4ffad6f934ba78742@epcms1p7>
2023-02-10  5:03     ` Jaewon Kim
2023-02-14 22:25       ` John Stultz

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