[PATCH xserver 14/23] dix/os: Merge priority computation into SmartScheduleClient

[Keith Packard]

Instead of having scheduling done in two places (one in
WaitForSomething, and the other in SmartScheduleClient), just stick
all of the scheduling in SmartScheduleClient.

Signed-off-by: Keith Packard <keithp at keithp.com>
---
 dix/dispatch.c | 22 ++++++++++++----------
 os/WaitFor.c   | 33 ++-------------------------------
 2 files changed, 14 insertions(+), 41 deletions(-)

diff --git a/dix/dispatch.c b/dix/dispatch.c
index 89c0a4e..f005983 100644
--- a/dix/dispatch.c
+++ b/dix/dispatch.c
@@ -244,15 +244,13 @@ void Dispatch(void);
 static int
 SmartScheduleClient(int *clientReady, int nready)
 {
-    ClientPtr pClient;
     int i;
     int client;
-    int bestPrio, best = 0;
+    ClientPtr pClient, best = NULL;
     int bestRobin, robin;
     long now = SmartScheduleTime;
     long idle;
 
-    bestPrio = -0x7fffffff;
     bestRobin = 0;
     idle = 2 * SmartScheduleSlice;
     for (i = 0; i < nready; i++) {
@@ -269,11 +267,16 @@ SmartScheduleClient(int *clientReady, int nready)
             (pClient->index -
              SmartLastIndex[pClient->smart_priority -
                             SMART_MIN_PRIORITY]) & 0xff;
-        if (pClient->smart_priority > bestPrio ||
-            (pClient->smart_priority == bestPrio && robin > bestRobin)) {
-            bestPrio = pClient->smart_priority;
+
+        /* pick the best client */
+        if (!best ||
+            pClient->priority > best->priority ||
+            (pClient->priority == best->priority &&
+             (pClient->smart_priority > best->smart_priority ||
+              (pClient->smart_priority == best->smart_priority && robin > bestRobin))))
+        {
+            best = pClient;
             bestRobin = robin;
-            best = client;
         }
 #ifdef SMART_DEBUG
         if ((now - SmartLastPrint) >= 5000)
@@ -286,8 +289,7 @@ SmartScheduleClient(int *clientReady, int nready)
         SmartLastPrint = now;
     }
 #endif
-    pClient = clients[best];
-    SmartLastIndex[bestPrio - SMART_MIN_PRIORITY] = pClient->index;
+    SmartLastIndex[best->smart_priority - SMART_MIN_PRIORITY] = best->index;
     /*
      * Set current client pointer
      */
@@ -312,7 +314,7 @@ SmartScheduleClient(int *clientReady, int nready)
     else {
         SmartScheduleSlice = SmartScheduleInterval;
     }
-    return best;
+    return best->index;
 }
 
 void
diff --git a/os/WaitFor.c b/os/WaitFor.c
index 994edf0..26673e4 100644
--- a/os/WaitFor.c
+++ b/os/WaitFor.c
@@ -326,17 +326,14 @@ WaitForSomething(int *pClientsReady)
     if (XFD_ANYSET(&clientsReadable)) {
 #ifndef WIN32
         for (i = 0; i < howmany(XFD_SETSIZE, NFDBITS); i++) {
-            int highest_priority = 0;
-
             while (clientsReadable.fds_bits[i]) {
-                int client_priority, client_index;
+                int client_index;
 
                 curclient = mffs(clientsReadable.fds_bits[i]) - 1;
                 client_index =  /* raphael: modified */
                     ConnectionTranslation[curclient +
                                           (i * (sizeof(fd_mask) * 8))];
 #else
-        int highest_priority = 0;
         fd_set savedClientsReadable;
 
         XFD_COPYSET(&clientsReadable, &savedClientsReadable);
@@ -346,33 +343,7 @@ WaitForSomething(int *pClientsReady)
             curclient = XFD_FD(&savedClientsReadable, i);
             client_index = GetConnectionTranslation(curclient);
 #endif
-            /*  We implement "strict" priorities.
-             *  Only the highest priority client is returned to
-             *  dix.  If multiple clients at the same priority are
-             *  ready, they are all returned.  This means that an
-             *  aggressive client could take over the server.
-             *  This was not considered a big problem because
-             *  aggressive clients can hose the server in so many
-             *  other ways :)
-             */
-            client_priority = clients[client_index]->priority;
-            if (nready == 0 || client_priority > highest_priority) {
-                /*  Either we found the first client, or we found
-                 *  a client whose priority is greater than all others
-                 *  that have been found so far.  Either way, we want
-                 *  to initialize the list of clients to contain just
-                 *  this client.
-                 */
-                pClientsReady[0] = client_index;
-                highest_priority = client_priority;
-                nready = 1;
-            }
-            /*  the following if makes sure that multiple same-priority
-             *  clients get batched together
-             */
-            else if (client_priority == highest_priority) {
-                pClientsReady[nready++] = client_index;
-            }
+            pClientsReady[nready++] = client_index;
 #ifndef WIN32
             clientsReadable.fds_bits[i] &= ~(((fd_mask) 1L) << curclient);
         }
-- 
2.8.0.rc3