From 85d2d4dd26c88b2f49efb2c7d440ee83f466c448 Mon Sep 17 00:00:00 2001
From: Fabian Keil <fk@fabiankeil.de>
Date: Thu, 18 Mar 2021 12:00:36 +0100
Subject: [PATCH] Add an experimental --scheduling-policy option

Only expected to work on FreeBSD-based systems.

While it was worth the try, the benchmark results at:
https://www.fabiankeil.de/gehacktes/privoxy-tls-benchmarks/#2021-03-18-siege-scheduling-policy
seem to suggest that changing the scheduling policy
doesn't actually improve things ...
---
 jcc.c | 48 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 48 insertions(+)

diff --git a/jcc.c b/jcc.c
index 3cc1b3f2..3c8fcadf 100644
--- a/jcc.c
+++ b/jcc.c
@@ -43,6 +43,9 @@
 #include <fcntl.h>
 #include <errno.h>
 #include <assert.h>
+#include <sched.h>
+#include <sys/time.h>
+#include <sys/resource.h>
 
 #ifdef _WIN32
 # ifndef FEATURE_PTHREAD
@@ -5304,6 +5307,43 @@ static void initialize_mutexes(void)
 #endif /* def MUTEX_LOCKS_AVAILABLE */
 }
 
+static void set_scheduling_policy(int new_scheduling_policy)
+{
+   struct sched_param sched_param;
+   int current_scheduling_policy = sched_getscheduler(0);
+
+   if (current_scheduling_policy == -1)
+   {
+      log_error(LOG_LEVEL_ERROR, "Failed to get the current "
+         "scheduling policy. Not setting new policy: %E");
+   }
+   else if (current_scheduling_policy != new_scheduling_policy)
+   {
+      log_error(LOG_LEVEL_INFO,
+         "Changing the scheduling policy from %d to %d",
+         current_scheduling_policy, new_scheduling_policy);
+      errno = 0;
+      sched_param.sched_priority = getpriority(PRIO_PROCESS, 0);
+      if (sched_param.sched_priority == -1 && errno != 0)
+      {
+         log_error(LOG_LEVEL_ERROR, "Failed to get the process priority. "
+            "Can't set new scheduling policy: %E");
+      }
+      else if (sched_setscheduler(0, new_scheduling_policy, &sched_param) != 0)
+      {
+         log_error(LOG_LEVEL_ERROR,
+            "Failed to set the scheduling policy from %d to %d: %E",
+            current_scheduling_policy, new_scheduling_policy);
+      }
+   }
+   else
+   {
+      log_error(LOG_LEVEL_INFO, "Scheduling policy %d is already set",
+         new_scheduling_policy);
+   }
+}
+
+
 /*********************************************************************
  *
  * Function    :  main
@@ -5421,6 +5461,14 @@ int main(int argc, char **argv)
          daemon_mode = 0;
       }
 
+      else if (strcmp(argv[argc_pos], "--scheduling-policy") == 0)
+      {
+         int scheduling_policy;
+         if (++argc_pos == argc) usage(argv[0]);
+         scheduling_policy = (int)strtol(argv[argc_pos], (char **)NULL, 10);
+         set_scheduling_policy(scheduling_policy);
+      }
+
       else if (strcmp(argv[argc_pos], "--pidfile") == 0)
       {
          if (++argc_pos == argc) usage(argv[0]);
-- 
2.30.0