Changeset 1bad1e2

Timestamp:

02/09/15 11:36:56 (6 years ago)

Author:

Richard Sanger <rsangerarj@…>

Branches:

4.0.1-hotfixes, cachetimestamps, develop, dpdk-ndag, etsilive, libtrace4, master, ndag_format, pfring, rc-4.0.1, rc-4.0.2, rc-4.0.3, rc-4.0.4, ringdecrementfix, ringperformance, ringtimestampfixes

Children:

6fc1ae7

Parents:

c5ac872

Message:

Fix performance regression in ring: introduced with the libtrace_halt check
We were always making a call to poll, even when a packet was available.

File:

• lib/format_linux.c (modified) (2 diffs)

lib/format_linux.c

@@ -1078 +1078 @@
         assert((((unsigned long) header) & (pagesize - 1)) == 0);
 
-        while (1) {
+        /* TP_STATUS_USER means that we can read the frame.
+         * When a slot does not have this flag set, the frame is not
+         * ready for consumption.
+         */
+        while (!(header->tp_status & TP_STATUS_USER)) {
                 pollset.fd = FORMAT(libtrace->format_data)->fd;
                 pollset.events = POLLIN;
@@ -1089 +1093 @@
                         return -1;
                 } else if (ret == 0) {
-                        /* Poll timed out - check if we should exit */
-                        if (libtrace_halt)
-                                return 0;
-                        continue;
-                }
-
-                /* TP_STATUS_USER means that we can use the frame.
-                 * When a slot does not have this flag set, the frame is not
-                 * ready for consumption.
-                 */
-                if (header->tp_status & TP_STATUS_USER)
-                        break;
+                        /* Poll timed out - check if we should exit */
+                        if (libtrace_halt)
+                                return 0;
+                        continue;
+                }
         }