From 37de5639e80d86c93ff8b328286168f050a10f06 Mon Sep 17 00:00:00 2001
From: Jan Sobol <sobol@cesnet.cz>
Date: Thu, 26 Sep 2024 09:50:05 +0200
Subject: [PATCH] dpdk-ring - prefetch dequeued packets before processing

---
 input/dpdk-ring.cpp | 8 ++++++++
 input/dpdk-ring.h   | 1 +
 2 files changed, 9 insertions(+)

diff --git a/input/dpdk-ring.cpp b/input/dpdk-ring.cpp
index 3af34e0a..6a612ce2 100644
--- a/input/dpdk-ring.cpp
+++ b/input/dpdk-ring.cpp
@@ -196,6 +196,7 @@ InputPlugin::Result DpdkRingReader::get(PacketBlock& packets)
     if (pkts_read_ == 0) {
         return Result::TIMEOUT;
     }
+    prefetchPackets();
     for (auto i = 0; i < pkts_read_; i++) {
         parse_packet(&opt,
             m_parser_stats,
@@ -256,4 +257,11 @@ void DpdkRingReader::getDynfieldInfo()
     }
 }
 
+void DpdkRingReader::prefetchPackets() {
+    for (auto i = 0; i < pkts_read_; i++) {
+        __builtin_prefetch(mbufs_[i], 0, 2);
+        __builtin_prefetch((uint8_t*)mbufs_[i] + 64, 0, 2);
+    }
+}
+
 } // namespace ipxp
\ No newline at end of file
diff --git a/input/dpdk-ring.h b/input/dpdk-ring.h
index 66fe2052..68dd9faf 100644
--- a/input/dpdk-ring.h
+++ b/input/dpdk-ring.h
@@ -152,6 +152,7 @@ class DpdkRingReader : public InputPlugin {
 
     telemetry::Content get_queue_telemetry();
     void getDynfieldInfo();
+    void prefetchPackets();
 
     std::vector<rte_mbuf *> mbufs_;
     std::uint16_t pkts_read_;