Support Zero-Copy for Netmap

This commit adds zero-copy through buffer swapping with extra buffer allocated on startup.

Netmap Buffers are now organized in pool much like click pool through a completed implementation of Luigi Rizzo's NetmapBufQ. A shared linked list allows multiple thread-local NetmapBufQ to exchange batches of buffers.

The amount of extra buffers allocated on startup is set using NetmapInfo, which is now a real element. NetmapBufQ and other old NetmapInfo methods (renamed more accurately NetmapDevice) are moved to lib/netmapdevice.cc

Also there was confusion between HAVE_NET_NETMAP_H and HAVE_NETMAP, and the ELEMENT_REQUIRES(netmap). It's not really needed to have part of the netmap subsystem built without HAVE_NETMAP, so HAVE_NET_NETMAP_H is changed by HAVE_NETMAP.

This is a first, minimal change just to introduce Zero Copy, it provides improvement but the send and receive method are nearly untouched and not re-worked in this commit.

Author: Tom Barbette

config-userlevel.h.in

@@ -113,9 +113,6 @@
 /* Define if you have the <netdb.h> header file. */
 #undef HAVE_NETDB_H
 
-/* Define if you have the <net/netmap.h> header file. */
-#undef HAVE_NET_NETMAP_H
-
 /* Define if you have the <netpacket/packet.h> header file. */
 #undef HAVE_NETPACKET_PACKET_H
 
@@ -214,6 +211,9 @@
 /* Define if a Click user-level driver might run multiple threads. */
 #undef HAVE_USER_MULTITHREAD
 
+/* Define if Netmap support is enabled. */
+#undef HAVE_NETMAP
+
 /* Define if a Click user-level driver uses Intel DPDK. */
 #undef HAVE_DPDK
 

configure

@@ -10705,11 +10705,15 @@ $as_echo "$ac_cv_working_net_netmap_h" >&6; }
     CPPFLAGS="$saveflags"
     if test "$HAVE_NETMAP" = yes -a "$use_netmap" != no; then
 
-$as_echo "#define HAVE_NET_NETMAP_H 1" >>confdefs.h
+$as_echo "#define HAVE_NETMAP 1" >>confdefs.h
 
+        EXTRA_DRIVER_OBJS="netmapdevice.o $EXTRA_DRIVER_OBJS"
+    else
+        HAVE_NETMAP=no
     fi
 
 
+
     if test "$HAVE_PCAP" != yes -a "$HAVE_NETMAP" != yes -a "$ac_cv_under_linux" != yes; then
         { $as_echo "$as_me:${as_lineno-$LINENO}: WARNING:
 =========================================

elements/userlevel/fromdevice.cc

@@ -472,9 +472,15 @@ FromDevice::emit_packet(WritablePacket *p, int extra_len, const Timestamp &ts)
     else
 	checked_output_push(1, p);
 }
+
+void
+FromDevice::emit_packet_arg(WritablePacket *p, int extra_len, const Timestamp &ts, void* arg) {
+	FromDevice* fd = static_cast<FromDevice*>(arg);
+	fd->emit_packet(p, extra_len, ts);
+}
 #endif
 
-#if FROMDEVICE_ALLOW_PCAP || FROMDEVICE_ALLOW_NETMAP
+#if FROMDEVICE_ALLOW_PCAP
 CLICK_ENDDECLS
 extern "C" {
 void
@@ -497,7 +503,6 @@ FromDevice_get_packet(u_char* clientdata,
 CLICK_DECLS
 #endif
 
-
 void
 FromDevice::selected(int, int)
 {
@@ -507,8 +512,7 @@ FromDevice::selected(int, int)
 #if FROMDEVICE_ALLOW_NETMAP
     if (_method == method_netmap) {
 	// Read and push() at most one burst of packets.
-	int r = _netmap.dispatch(_burst,
-		reinterpret_cast<nm_cb_t>(FromDevice_get_packet), (u_char *) this);
+	int r = _netmap.receive(_burst, _headroom, emit_packet_arg, this);
 	if (r > 0) {
 	    _count += r;
 	    _task.reschedule();
@@ -570,8 +574,7 @@ FromDevice::run_task(Task *)
 # if FROMDEVICE_ALLOW_NETMAP
     if (_method == method_netmap) {
 	// Read and push() at most one burst of packets.
-	r = _netmap.dispatch(_burst,
-		reinterpret_cast<nm_cb_t>(FromDevice_get_packet), (u_char *) this);
+	r = _netmap.receive(_burst,_headroom,emit_packet_arg, this);
 	if (r < 0 && ++_pcap_complaints < 5)
 	    ErrorHandler::default_handler()->error("%p{element}: %s",
 			this, "nm_dispatch failed");
@@ -652,5 +655,5 @@ FromDevice::add_handlers()
 }
 
 CLICK_ENDDECLS
-ELEMENT_REQUIRES(userlevel FakePcap KernelFilter NetmapInfo)
+ELEMENT_REQUIRES(userlevel FakePcap KernelFilter)
 EXPORT_ELEMENT(FromDevice)

elements/userlevel/fromdevice.hh

@@ -18,9 +18,9 @@ int pcap_setnonblock(pcap_t *p, int nonblock, char *errbuf);
 }
 #endif
 
-#if HAVE_NET_NETMAP_H
+#if HAVE_NETMAP
 # define FROMDEVICE_ALLOW_NETMAP 1
-# include "elements/userlevel/netmapinfo.hh"
+# include <click/netmapdevice.hh>
 #endif
 
 #if FROMDEVICE_ALLOW_NETMAP || FROMDEVICE_ALLOW_PCAP
@@ -187,7 +187,6 @@ class FromDevice : public Element { public:
 #else
     inline int fd() const		{ return -1; }
 #endif
-
     void selected(int fd, int mask);
 
 #if FROMDEVICE_ALLOW_PCAP
@@ -203,7 +202,7 @@ class FromDevice : public Element { public:
 #endif
 
 #if FROMDEVICE_ALLOW_NETMAP
-    const NetmapInfo *netmap() const { return _method == method_netmap ? &_netmap : 0; }
+    const NetmapDevice *netmap() const { return _method == method_netmap ? &_netmap : 0; }
 #endif
 
 #if FROMDEVICE_ALLOW_NETMAP || FROMDEVICE_ALLOW_PCAP
@@ -222,13 +221,14 @@ class FromDevice : public Element { public:
 #endif
 #if FROMDEVICE_ALLOW_PCAP || FROMDEVICE_ALLOW_NETMAP
     void emit_packet(WritablePacket *p, int extra_len, const Timestamp &ts);
+    static void emit_packet_arg(WritablePacket *p, int extra_len, const Timestamp &ts, void* arg);
 #endif
 #if FROMDEVICE_ALLOW_PCAP
     pcap_t *_pcap;
     int _pcap_complaints;
 #endif
 #if FROMDEVICE_ALLOW_NETMAP
-    NetmapInfo _netmap;
+    NetmapDevice _netmap;
     int netmap_dispatch();
 #endif
 #if FROMDEVICE_ALLOW_PCAP || FROMDEVICE_ALLOW_NETMAP

elements/userlevel/netmapinfo.cc

@@ -1,9 +1,8 @@
 // -*- mode: c++; c-basic-offset: 4 -*-
 /*
  * netmapinfo.{cc,hh} -- library for interfacing with netmap
- * Eddie Kohler, Luigi Rizzo
  *
- * Copyright (c) 2012 Eddie Kohler
+ * Copyright (c) 2015 Tom Barbette
  *
  * Permission is hereby granted, free of charge, to any person obtaining a
  * copy of this software and associated documentation files (the "Software"),
@@ -17,130 +16,29 @@
  */
 
 #include <click/config.h>
-#include <click/glue.hh>
-#if HAVE_NET_NETMAP_H
-#define NETMAP_WITH_LIBS
+#include <click/args.hh>
+#include <click/error.hh>
 #include "netmapinfo.hh"
-#include <sys/mman.h>
-#include <sys/ioctl.h>
-#include <click/sync.hh>
-#include <unistd.h>
-#include <fcntl.h>
-CLICK_DECLS
-
-/*
- * keep a list of netmap ports so matching the name we
- * can recycle the regions
- */
-static Spinlock netmap_memory_lock;
-//static struct NetmapInfo *netmap_ports;
 
-int
-NetmapInfo::open(const String &ifname,
-		       bool always_error, ErrorHandler *errh)
-{
-    click_chatter("%s ifname %s\n", __FUNCTION__, ifname.c_str());
-    ErrorHandler *initial_errh = always_error ? errh : ErrorHandler::silent_handler();
+CLICK_DECLS
 
-    netmap_memory_lock.acquire();
-    // for the time being, just a new block
-    do {
-	desc = nm_open(ifname.c_str(), NULL, 0, NULL);
-	if (desc == NULL) {
-	    initial_errh->error("nm_open(%s): %s", ifname.c_str(), strerror(errno));
-	    break;
+int NetmapInfo::configure(Vector<String> &conf, ErrorHandler *errh) {
+	if (instance) {
+		return errh->error("You cannot place multiple instances of NetmapInfo !");
 	}
-	click_chatter("%s %s memsize %d mem %p buf_start %p buf_end %p",
-		__FUNCTION__, desc->req.nr_name,
-		desc->memsize, desc->mem, desc->buf_start, desc->buf_end);
-	bufq.init(desc->buf_start, desc->buf_end,
-		desc->some_ring->nr_buf_size);
-	/* eventually try to match the region */
-	destructor_arg = this;
-	click_chatter("private mapping for %s\n", ifname.c_str());
-    } while (0);
-    netmap_memory_lock.release();
-    return desc ? desc->fd : -1;
-}
+	instance = this;
+	if (Args(conf, this, errh)
+			.read_p("EXTRA_BUFFER", NetmapDevice::global_alloc)
+			.complete() < 0)
+		return -1;
 
-void
-NetmapInfo::initialize_rings_rx(int timestamp)
-{
-    click_chatter("%s timestamp %d\n", __FUNCTION__, timestamp);
-    if (timestamp >= 0) {
-	int flags = (timestamp > 0 ? NR_TIMESTAMP : 0);
-	for (unsigned i = desc->first_rx_ring; i <= desc->last_rx_ring; ++i)
-	    NETMAP_RXRING(desc->nifp, i)->flags = flags;
-    }
+	return 0;
 }
 
-void
-NetmapInfo::initialize_rings_tx()
-{
-    click_chatter("%s\n", __FUNCTION__);
-}
-
-int
-NetmapInfo::dispatch(int count, nm_cb_t cb, u_char *arg)
-{
-	return nm_dispatch(desc, count, cb, arg);
-}
-
-bool
-NetmapInfo::send_packet(Packet *p, int noutputs)
-{
-	int ret = nm_inject(desc, p->data(), p->length());
-	if (0) click_chatter("%s buf %p size %d returns %d\n",
-		__FUNCTION__, p->data(), p->length(), ret);
-	return ret > 0 ? 0 : -1;
-#if 0
-    // we can do a smart nm_inject
-    for (unsigned ri = desc->first_tx_ring; ri <= desc->last_tx_ring; ++ri) {
-        struct netmap_ring *ring = NETMAP_TXRING(desc->nifp, ri);
-        if (nm_ring_empty(ring))
-            continue;
-        unsigned cur = ring->cur;
-        unsigned buf_idx = ring->slot[cur].buf_idx;
-        if (buf_idx < 2)
-            continue;
-        unsigned char *buf = (unsigned char *) NETMAP_BUF(ring, buf_idx);
-        uint32_t p_length = p->length();
-        if (NetmapInfo::is_netmap_buffer(p)
-            && !p->shared()
-	    && p->buffer() == p->data()
-            && (char *)p->buffer() >= desc->buf_start
-	    && (char *)p->buffer() < desc->buf_end
-            && noutputs == 0) {
-            // put the original buffer in the freelist
-            NetmapInfo::buffer_destructor(buf, 0, (void *)this);
-            // now enqueue
-            ring->slot[cur].buf_idx = NETMAP_BUF_IDX(ring, (char *) p->buffer());
-            ring->slot[cur].flags |= NS_BUF_CHANGED;
-            // and make sure nobody uses this packet
-            p->reset_buffer();
-        } else
-            memcpy(buf, p->data(), p_length);
-        ring->slot[cur].len = p_length;
-        __asm__ volatile("" : : : "memory");
-        ring->head = ring->cur = nm_ring_next(ring, cur);
-        return 0;
-    }
-    errno = ENOBUFS;
-    return -1;
-#endif
-}
-void
-NetmapInfo::close(int fd)
-{
-    click_chatter("fd %d interface %s\n",
-	fd, desc->req.nr_name);
-    netmap_memory_lock.acquire();
-    // unlink from the list ?
-    nm_close(desc);
-    desc = 0;
-    netmap_memory_lock.release();
-}
+NetmapInfo* NetmapInfo::instance = 0;
 
 CLICK_ENDDECLS
-#endif
-ELEMENT_PROVIDES(NetmapInfo)
+
+ELEMENT_REQUIRES(userlevel netmap)
+EXPORT_ELEMENT(NetmapInfo)
+ELEMENT_MT_SAFE(NetmapInfo)