55 lines
2.3 KiB
Diff
55 lines
2.3 KiB
Diff
From: Arthur Kiyanovski <akiyano@amazon.com>
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Date: Thu, 11 Oct 2018 11:26:23 +0300
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Subject: [PATCH 09/19] net: ena: limit refill Rx threshold to 256 to avoid
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latency issues
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Origin: https://git.kernel.org/linus/0574bb806dad29a3dada0ee42b01645477d48282
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Currently Rx refill is done when the number of required descriptors is
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above 1/8 queue size. With a default of 1024 entries per queue the
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threshold is 128 descriptors.
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There is intention to increase the queue size to 8196 entries.
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In this case threshold of 1024 descriptors is too large and can hurt
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latency.
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Add another limitation to Rx threshold to be at most 256 descriptors.
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Signed-off-by: Arthur Kiyanovski <akiyano@amazon.com>
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Signed-off-by: David S. Miller <davem@davemloft.net>
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---
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drivers/net/ethernet/amazon/ena/ena_netdev.c | 4 +++-
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drivers/net/ethernet/amazon/ena/ena_netdev.h | 5 +++--
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2 files changed, 6 insertions(+), 3 deletions(-)
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Index: linux/drivers/net/ethernet/amazon/ena/ena_netdev.c
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===================================================================
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--- linux.orig/drivers/net/ethernet/amazon/ena/ena_netdev.c
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+++ linux/drivers/net/ethernet/amazon/ena/ena_netdev.c
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@@ -1122,7 +1122,9 @@ static int ena_clean_rx_irq(struct ena_r
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rx_ring->next_to_clean = next_to_clean;
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refill_required = ena_com_free_desc(rx_ring->ena_com_io_sq);
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- refill_threshold = rx_ring->ring_size / ENA_RX_REFILL_THRESH_DIVIDER;
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+ refill_threshold =
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+ min_t(int, rx_ring->ring_size / ENA_RX_REFILL_THRESH_DIVIDER,
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+ ENA_RX_REFILL_THRESH_PACKET);
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/* Optimization, try to batch new rx buffers */
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if (refill_required > refill_threshold) {
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Index: linux/drivers/net/ethernet/amazon/ena/ena_netdev.h
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===================================================================
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--- linux.orig/drivers/net/ethernet/amazon/ena/ena_netdev.h
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+++ linux/drivers/net/ethernet/amazon/ena/ena_netdev.h
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@@ -106,10 +106,11 @@
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*/
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#define ENA_TX_POLL_BUDGET_DIVIDER 4
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-/* Refill Rx queue when number of available descriptors is below
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- * QUEUE_SIZE / ENA_RX_REFILL_THRESH_DIVIDER
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+/* Refill Rx queue when number of required descriptors is above
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+ * QUEUE_SIZE / ENA_RX_REFILL_THRESH_DIVIDER or ENA_RX_REFILL_THRESH_PACKET
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*/
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#define ENA_RX_REFILL_THRESH_DIVIDER 8
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+#define ENA_RX_REFILL_THRESH_PACKET 256
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/* Number of queues to check for missing queues per timer service */
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#define ENA_MONITORED_TX_QUEUES 4
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