[ovs-dev] [PATCH v5 3/4] netdev-dpdk: Autofill lcore coremask if absent

[Aaron Conole]

The user has control over the DPDK internal lcore coremask, but this
parameter can be autofilled with a bit more intelligence. If the user
does not fill this parameter in, we use the lowest set bit in the
current task CPU affinity. Otherwise, we will reassign the current
thread to the specified lcore mask, in addition to the dpdk lcore
threads.

Signed-off-by: Aaron Conole <aconole at redhat.com>
Cc: Kevin Traynor <kevin.traynor at intel.com>
---
v2:
* Fix a conditional branch coding standard issue
* When lcore coremask is set, do not reset the affinities as
  suggested by Kevin Traynor

v3:
* Fixed grow_argv calls
* Fixed an error in argc assignment after 'break;' introduced
  in v2
* Switched to using xstrdup

v4,v5:
* No change

 lib/netdev-dpdk.c | 58 ++++++++++++++++++++++++++++++++++++++++++++-----------
 1 file changed, 47 insertions(+), 11 deletions(-)

diff --git a/lib/netdev-dpdk.c b/lib/netdev-dpdk.c
index b7bb3eb..29b3db2 100644
--- a/lib/netdev-dpdk.c
+++ b/lib/netdev-dpdk.c
@@ -65,6 +65,8 @@ static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(5, 20);
 #define OVS_CACHE_LINE_SIZE CACHE_LINE_SIZE
 #define OVS_VPORT_DPDK "ovs_dpdk"
 
+#define MAX_BUFSIZ 256
+
 /*
  * need to reserve tons of extra space in the mbufs so we can align the
  * DMA addresses to 4KB.
@@ -2168,7 +2170,8 @@ grow_argv(char ***argv, size_t cur_siz, size_t grow_by)
 }
 
 static int
-get_dpdk_args(const struct ovsrec_open_vswitch *ovs_cfg, char ***argv)
+get_dpdk_args(const struct ovsrec_open_vswitch *ovs_cfg, char ***argv,
+              int argc)
 {
     struct dpdk_options_map {
         const char *ovs_configuration;
@@ -2176,14 +2179,14 @@ get_dpdk_args(const struct ovsrec_open_vswitch *ovs_cfg, char ***argv)
         bool default_enabled;
         const char *default_value;
     } opts[] = {
-        {"dpdk-lcore-mask", "-c", true, "0x1"},
+        {"dpdk-lcore-mask", "-c", false, NULL},
         /* XXX: DPDK 2.2.0 support, the true should become false for -n */
         {"dpdk-mem-channels", "-n", true, "4"},
         {"dpdk-alloc-mem", "-m", false, NULL},
         {"dpdk-socket-mem", "--socket-mem", true, "1024,0"},
         {"dpdk-hugepage-dir", "--huge-dir", false, NULL},
     };
-    int i, ret = 1;
+    int i, ret = argc;
 
     for(i = 0; i < (sizeof(opts) / sizeof(opts[0])); ++i) {
         const char *lookup = smap_get(&ovs_cfg->other_config,
@@ -2226,7 +2229,8 @@ __dpdk_init(const struct ovsrec_open_vswitch *ovs_cfg)
 {
     char **argv = NULL;
     int result;
-    int argc;
+    int argc = 0, argc_tmp;
+    bool auto_determine = true;
     int err;
     cpu_set_t cpuset;
 
@@ -2260,12 +2264,41 @@ __dpdk_init(const struct ovsrec_open_vswitch *ovs_cfg)
         ovs_abort(0, "Thread getaffinity error %d.", err);
     }
 
-    argv = grow_argv(&argv, 0, 1);
+    argv = grow_argv(&argv, argc, argc+1);
     if (!argv) {
         ovs_abort(0, "Unable to allocate an initial argv.");
     }
-    argv[0] = xstrdup("ovs"); /* TODO use prctl to get process name */
-    argc = get_dpdk_args(ovs_cfg, &argv);
+    argv[argc++] = xstrdup("ovs"); /* TODO use prctl to get process name */
+    argc_tmp = get_dpdk_args(ovs_cfg, &argv, argc);
+
+    while(argc_tmp != argc) {
+        if (!strcmp("-c", argv[argc++])) {
+            auto_determine = false;
+            break;
+        }
+    }
+    argc = argc_tmp;
+
+    /**
+     * NOTE: This is an unsophisticated mechanism for determining the DPDK
+     * lcore for the DPDK Master.
+     */
+    if (auto_determine) {
+        int i;
+        for (i = 0; i < CPU_SETSIZE; i++) {
+            if (CPU_ISSET(i, &cpuset)) {
+                char buf[MAX_BUFSIZ];
+                snprintf(buf, MAX_BUFSIZ, "0x%08llX", (1ULL<<i));
+                argv = grow_argv(&argv, argc, 2);
+                if (!argv) {
+                    ovs_abort(0, "Unable to grow argv for coremask");
+                }
+                argv[argc++] = xstrdup("-c");
+                argv[argc++] = xstrdup(buf);
+                i = CPU_SETSIZE;
+            }
+        }
+    }
 
     argv = grow_argv(&argv, argc, 1);
     if (!argv) {
@@ -2281,10 +2314,13 @@ __dpdk_init(const struct ovsrec_open_vswitch *ovs_cfg)
         ovs_abort(result, "Cannot init EAL");
     }
 
-    /* Set the main thread affinity back to pre rte_eal_init() value */
-    err = pthread_setaffinity_np(pthread_self(), sizeof(cpu_set_t), &cpuset);
-    if (err) {
-        ovs_abort(0, "Thread getaffinity error %d.", err);
+    if (auto_determine) {
+        /* Set the main thread affinity back to pre rte_eal_init() value */
+        err = pthread_setaffinity_np(pthread_self(), sizeof(cpu_set_t),
+                                     &cpuset);
+        if (err) {
+            ovs_abort(0, "Thread getaffinity error %d.", err);
+        }
     }
 
     dpdk_argv = argv;
-- 
2.5.0