Process packets in bursts.HEADreplicant-6.0-0004-transitionreplicant-6.0-0004-rc6replicant-6.0-0004-rc5-transitionreplicant-6.0-0004-rc5replicant-6.0-0004-rc4replicant-6.0-0004-rc3replicant-6.0-0004-rc2replicant-6.0-0004-rc1replicant-6.0-0004replicant-6.0-0003replicant-6.0-0002replicant-6.0-0001stable/cm-13.0-ZNH5Ycm-13.0

Add a "packet_burst" config option that will cause clatd to read
(and write) in bursts of up to that number of packets, instead of
always only reading one packet at a time. This reduces poll
overhead and improves performance.

The variable is initially set to 10.

Bug: 24113287
Change-Id: I7feba4127538c5a89f92e0ebea1fb75971d6b901

5 files changed, 44 insertions, 27 deletions

diff --git a/clatd.c b/clatd.c
index 64f2ebe..1d21977 100644
--- a/clatd.c
+++ b/clatd.c
@@ -333,39 +333,42 @@ void configure_interface(const char *uplink_interface, const char *plat_prefix,
 void read_packet(int read_fd, int write_fd, int to_ipv6) {
   ssize_t readlen;
   uint8_t buf[PACKETLEN], *packet;
+  int numread = 0;
 
-  readlen = read(read_fd, buf, PACKETLEN);
+  do {
+    readlen = read(read_fd, buf, PACKETLEN);
 
-  if(readlen < 0) {
-    if (errno != EAGAIN) {
-      logmsg(ANDROID_LOG_WARN,"read_packet/read error: %s", strerror(errno));
+    if(readlen < 0) {
+      if (errno != EAGAIN) {
+        logmsg(ANDROID_LOG_WARN,"read_packet/read error: %s", strerror(errno));
+      }
+      return;
+    } else if(readlen == 0) {
+      logmsg(ANDROID_LOG_WARN,"read_packet/tun interface removed");
+      running = 0;
+      return;
     }
-    return;
-  } else if(readlen == 0) {
-    logmsg(ANDROID_LOG_WARN,"read_packet/tun interface removed");
-    running = 0;
-    return;
-  }
 
-  struct tun_pi *tun_header = (struct tun_pi *) buf;
-  if (readlen < (ssize_t) sizeof(*tun_header)) {
-    logmsg(ANDROID_LOG_WARN,"read_packet/short read: got %ld bytes", readlen);
-    return;
-  }
+    struct tun_pi *tun_header = (struct tun_pi *) buf;
+    if (readlen < (ssize_t) sizeof(*tun_header)) {
+      logmsg(ANDROID_LOG_WARN,"read_packet/short read: got %ld bytes", readlen);
+      return;
+    }
 
-  uint16_t proto = ntohs(tun_header->proto);
-  if (proto != ETH_P_IP) {
-    logmsg(ANDROID_LOG_WARN, "%s: unknown packet type = 0x%x", __func__, proto);
-    return;
-  }
+    uint16_t proto = ntohs(tun_header->proto);
+    if (proto != ETH_P_IP) {
+      logmsg(ANDROID_LOG_WARN, "%s: unknown packet type = 0x%x", __func__, proto);
+      return;
+    }
 
-  if(tun_header->flags != 0) {
-    logmsg(ANDROID_LOG_WARN, "%s: unexpected flags = %d", __func__, tun_header->flags);
-  }
+    if(tun_header->flags != 0) {
+      logmsg(ANDROID_LOG_WARN, "%s: unexpected flags = %d", __func__, tun_header->flags);
+    }
 
-  packet = (uint8_t *) (tun_header + 1);
-  readlen -= sizeof(*tun_header);
-  translate_packet(write_fd, to_ipv6, packet, readlen, TP_CSUM_NONE);
+    packet = (uint8_t *) (tun_header + 1);
+    readlen -= sizeof(*tun_header);
+    translate_packet(write_fd, to_ipv6, packet, readlen, TP_CSUM_NONE);
+  } while (++numread < Global_Clatd_Config.packet_burst);
 }
 
 /* function: recv_loop
diff --git a/clatd.conf b/clatd.conf
index ff80975..dcbdd09 100644
--- a/clatd.conf
+++ b/clatd.conf
@@ -20,3 +20,6 @@ plat_from_dns64_hostname ipv4only.arpa
 # plat subnet to send ipv4 traffic to. This is a /96 subnet.
 # This setting only makes sense with: plat_from_dns64 no
 #plat_subnet 2001:db8:1:2:3:4::
+
+# how many packets to process at a time.
+packet_burst 10
diff --git a/config.c b/config.c
index b147868..84a1e0e 100644
--- a/config.c
+++ b/config.c
@@ -371,6 +371,13 @@ int read_config(const char *file, const char *uplink_interface, const char *plat
     Global_Clatd_Config.use_dynamic_iid = 1;
   }
 
+  if(!config_item_int16_t(root, "packet_burst", "10", &Global_Clatd_Config.packet_burst))
+    goto failed;
+
+  if (Global_Clatd_Config.packet_burst < 1 || Global_Clatd_Config.packet_burst > 50) {
+    logmsg(ANDROID_LOG_FATAL, "invalid value packet_burst %d", Global_Clatd_Config.packet_burst);
+  }
+
   return 1;
 
 failed:
@@ -392,4 +399,5 @@ void dump_config() {
   logmsg(ANDROID_LOG_DEBUG,"ipv4_local_prefixlen = %d", Global_Clatd_Config.ipv4_local_prefixlen);
   logmsg(ANDROID_LOG_DEBUG,"plat_subnet = %s",inet_ntop(AF_INET6, &Global_Clatd_Config.plat_subnet, charbuffer, sizeof(charbuffer)));
   logmsg(ANDROID_LOG_DEBUG,"default_pdp_interface = %s",Global_Clatd_Config.default_pdp_interface);
+  logmsg(ANDROID_LOG_DEBUG,"packet burst = %d",Global_Clatd_Config.packet_burst);
 }
diff --git a/config.h b/config.h
index e31a81d..f562fdf 100644
--- a/config.h
+++ b/config.h
@@ -35,6 +35,7 @@ struct clat_config {
   char *default_pdp_interface;
   char *plat_from_dns64_hostname;
   int use_dynamic_iid;
+  int16_t packet_burst;
 };
 
 extern struct clat_config Global_Clatd_Config;
diff --git a/ring.c b/ring.c
index 17f8026..dcf4310 100644
--- a/ring.c
+++ b/ring.c
@@ -24,6 +24,7 @@
 #include <linux/if.h>
 #include <linux/if_packet.h>
 
+#include "config.h"
 #include "logging.h"
 #include "ring.h"
 #include "translate.h"
@@ -116,9 +117,10 @@ static struct tpacket2_hdr* ring_advance(struct packet_ring *ring) {
  * to_ipv6  - whether the packet is to be translated to ipv6 or ipv4
  */
 void ring_read(struct packet_ring *ring, int write_fd, int to_ipv6) {
+  int numread = 0;
   struct tpacket2_hdr *tp = ring->next;
   uint16_t val = TP_CSUM_NONE;
-  if (tp->tp_status & TP_STATUS_USER) {
+  while (tp->tp_status & TP_STATUS_USER && numread++ < Global_Clatd_Config.packet_burst) {
     //We expect only GRO coalesced packets to have TP_STATUS_CSUMNOTREADY
     //(ip_summed = CHECKSUM_PARTIAL) in this path. Note that these packets have already gone
     //through checksum validation in GRO engine. CHECKSUM_PARTIAL is defined to be 3 while