MEDIUM: fd: Add the tune.fd.tables option

Add a new experimental option, tune.fd.tables, that can be set to
either "shared" (the default) or "per-thread-group", to enable
per-thread group file descriptor tables.
This can give a nice performance boost when running with a lot of
threads, as we observe a lot of contention on the file descriptor table
lock in the kernel.

diff --git a/src/cfgparse-global.c b/src/cfgparse-global.c
index d9f25afd06ec4832cbdff66702a9275a2cf09876..34200cc411687c9dca902777be87af6fcde0b7b2 100644 (file)
--- a/src/cfgparse-global.c
+++ b/src/cfgparse-global.c
@@ -1484,6 +1484,22 @@ static int cfg_parse_global_tune_opts(char **args, int section_type,
                }
                return 0;
        }
+       else if (strcmp(args[0], "tune.fd.tables") == 0) {
+#ifdef CLONE_FILES
+               if (strcmp(args[1], "per-thread-group") == 0)
+                       global.tune.options |= GTUNE_NO_TG_FD_SHARING;
+               else if (strcmp(args[1], "shared") == 0)
+                       global.tune.options &= ~GTUNE_NO_TG_FD_SHARING;
+               else {
+                       memprintf(err, "'%s' expects 'shared' or 'per-thread-group', got '%s'", args[0], args[1]);
+                       return -1;
+               }
+               return 0;
+#else
+               memprintf(err, "'%s' is not supported on that platform", args[0]);
+               return -1;
+#endif
+       }
        else {
                BUG_ON(1, "Triggered in cfg_parse_global_tune_opts() by unsupported keyword.");
                return -1;
@@ -1882,6 +1898,7 @@ static struct cfg_kw_list cfg_kws = {ILH, {
        { CFG_GLOBAL, "tune.defaults.purge", cfg_parse_global_tune_opts },
        { CFG_GLOBAL, "tune.disable-fast-forward", cfg_parse_global_tune_forward_opts },
        { CFG_GLOBAL, "tune.disable-zero-copy-forwarding", cfg_parse_global_tune_forward_opts },
+       { CFG_GLOBAL, "tune.fd.tables", cfg_parse_global_tune_opts, KWF_EXPERIMENTAL },
        { CFG_GLOBAL, "tune.glitches.kill.cpu-usage", cfg_parse_global_tune_opts },
        { CFG_GLOBAL, "tune.http.cookielen", cfg_parse_global_tune_opts },
        { CFG_GLOBAL, "tune.http.logurilen", cfg_parse_global_tune_opts },