On 14 Aug 2019, at 9:45, Ilya Maximets wrote:

On 13.08.2019 19:46, Eelco Chaudron wrote:

On 13 Aug 2019, at 18:37, Ilya Maximets wrote:

This is highly useful to see on which core PMD is running by
only looking at the thread name. Thread Id still allows to
distinguish different threads running on the same core over the time:

   |dpif_netdev(pmd-c10/id:53)|DBG|Creating 2. subtable <...>
   |dpif_netdev(pmd-c10/id:53)|DBG|flow_add: <...>, actions:2
   |dpif_netdev(pmd-c09/id:70)|DBG|Core 9 processing port <..>

In gdb, top or any other utility it's useful to quickly catch up
needed thread without parsing logs, memory or matching threads by port
names they're handling.

Signed-off-by: Ilya Maximets <i.maxim...@samsung.com>
 lib/dpif-netdev.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/lib/dpif-netdev.c b/lib/dpif-netdev.c
index d0a1c58ad..34ba03836 100644
--- a/lib/dpif-netdev.c
+++ b/lib/dpif-netdev.c
@@ -4735,9 +4735,16 @@ reconfigure_pmd_threads(struct dp_netdev *dp)
     FOR_EACH_CORE_ON_DUMP(core, pmd_cores) {
         pmd = dp_netdev_get_pmd(dp, core->core_id);
         if (!pmd) {
+            struct ds name = DS_EMPTY_INITIALIZER;
             pmd = xzalloc(sizeof *pmd);
             dp_netdev_configure_pmd(pmd, dp, core->core_id, core->numa_id); -            pmd->thread = ovs_thread_create("pmd", pmd_thread_main, pmd);
+            ds_put_format(&name, "pmd-c%02d/id:", core->core_id);

This is a really good idea :) One remark should we make it %03d?

There is a hard limit for the thread name. It's 15 meaningful chars excluding the terminating null byte. 'pmd-c02/id:' is 11 bytes wide keeping 4 bytes for the thread id. 'pmd-c002/id:' is 12 bytes wide with only 3 bytes remaining for id. Thread ids could easily become big ( > 1000) for a long running process, that is
why %02d was chosen, to save some space.

BTW, even on a systems with 100+ CPUs I'm usually placing OVS threads on a lower cores. Anyway, this is only the matter of a bit more visual beauty in the logs.

What do you think?

Makes sense

Acked-by: Eelco Chaudron <echau...@redhat.com>

+            pmd->thread = ovs_thread_create(ds_cstr(&name), +                                            pmd_thread_main, pmd);
+            ds_destroy(&name);
             VLOG_INFO("PMD thread on numa_id: %d, core id: %2d created.",                        pmd->numa_id, pmd->core_id);
             changed = true;

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