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From 0c7cb8b132f28cd150eb578a73c959de736364a2 Mon Sep 17 00:00:00 2001
From: Ioana Radulescu <ruxandra.radulescu@nxp.com>
Date: Mon, 16 Sep 2019 13:15:02 +0300
Subject: [PATCH] dpaa2-eth: Update FQ taildrop threshold and buffer pool count
Now that we have congestion group taildrop configured at all
times, we can afford to increase the frame queue taildrop
threshold; this will ensure a better response when receiving
bursts of large-sized frames.
Also decouple the buffer pool count from the Rx FQ taildrop
threshold, as above change would increase it too much. Instead,
keep the old count as a hardcoded value.
With the new limits, we try to ensure that:
* we allow enough leeway for large frame bursts (by buffering
enough of them in queues to avoid heavy dropping in case of
bursty traffic, but when overall ingress bandwidth is manageable)
* allow pending frames to be evenly spread between ingress FQs,
regardless of frame size
* avoid dropping frames due to the buffer pool being empty; this
is not a bad behaviour per se, but system overall response is
more linear and predictable when frames are dropped at frame
queue/group level.
Signed-off-by: Ioana Radulescu <ruxandra.radulescu@nxp.com>
---
drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.h | 23 +++++++++++------------
1 file changed, 11 insertions(+), 12 deletions(-)
--- a/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.h
+++ b/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.h
@@ -35,24 +35,24 @@
/* Convert L3 MTU to L2 MFL */
#define DPAA2_ETH_L2_MAX_FRM(mtu) ((mtu) + VLAN_ETH_HLEN)
-/* Set the taildrop threshold (in bytes) to allow the enqueue of several jumbo
- * frames in the Rx queues (length of the current frame is not
- * taken into account when making the taildrop decision)
+/* Set the taildrop threshold (in bytes) to allow the enqueue of a large
+ * enuough number of jumbo frames in the Rx queues (length of the current
+ * frame is not taken into account when making the taildrop decision)
*/
-#define DPAA2_ETH_FQ_TAILDROP_THRESH (64 * 1024)
+#define DPAA2_ETH_FQ_TAILDROP_THRESH (1024 * 1024)
/* Maximum number of Tx confirmation frames to be processed
* in a single NAPI call
*/
#define DPAA2_ETH_TXCONF_PER_NAPI 256
-/* Buffer quota per queue. Must be large enough such that for minimum sized
- * frames taildrop kicks in before the bpool gets depleted, so we compute
- * how many 64B frames fit inside the taildrop threshold and add a margin
- * to accommodate the buffer refill delay.
+/* Buffer qouta per channel. We want to keep in check number of ingress frames
+ * in flight: for small sized frames, congestion group taildrop may kick in
+ * first; for large sizes, Rx FQ taildrop threshold will ensure only a
+ * reasonable number of frames will be pending at any given time.
+ * Ingress frame drop due to buffer pool depletion should be a corner case only
*/
-#define DPAA2_ETH_MAX_FRAMES_PER_QUEUE (DPAA2_ETH_FQ_TAILDROP_THRESH / 64)
-#define DPAA2_ETH_NUM_BUFS (DPAA2_ETH_MAX_FRAMES_PER_QUEUE + 256)
+#define DPAA2_ETH_NUM_BUFS 1280
#define DPAA2_ETH_REFILL_THRESH \
(DPAA2_ETH_NUM_BUFS - DPAA2_ETH_BUFS_PER_CMD)
@@ -62,8 +62,7 @@
* taildrop kicks in
*/
#define DPAA2_ETH_CG_TAILDROP_THRESH(priv) \
- (DPAA2_ETH_MAX_FRAMES_PER_QUEUE * dpaa2_eth_queue_count(priv) / \
- dpaa2_eth_tc_count(priv))
+ (1024 * dpaa2_eth_queue_count(priv) / dpaa2_eth_tc_count(priv))
/* Maximum number of buffers that can be acquired/released through a single
* QBMan command
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