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Re: [Xen-devel] [PATCH] xen, credit2: Avoid extra c2t calcuation in csched_runtime



On 24/01/13 15:55, George Dunlap wrote:

      struct csched_runqueue_data *rqd = RQD(ops, cpu);
      struct list_head *runq = &rqd->runq;
        if ( is_idle_vcpu(snext->vcpu) )
          return CSCHED_MAX_TIMER;
  -    /* Basic time */
-    time = c2t(rqd, snext->credit, snext);
+    /* General algorithm:
+     * 1) Run until snext's credit will be 0
+     * 2) But if someone is waiting, run until snext's credit is equal
+     * to his
+ * 3) But never run longer than MAX_TIMER or shorter than MIN_TIMER.
+     */
  -    /* Next guy on runqueue */
+    /* 1) Basic time: Run until credit is 0. */
+    rt_credit = snext->credit;
+
+    /* 2) If there's someone waiting whose credit is positive,
... who's ...?

Nope. :-) "Who's" is short for "who is". "Whose" is a pronoun which links back to "someone waiting". (I suppose "whose" is the person version of "which", which I used in both the previous sentence and this one.)

OK, for the really serious grammar students:

"Whose" isn't a pronoun, it's an adjective indicating "owned by who" or "of who"; in this case, "whose" is modifying "credit". It's a similar construction to the following:

"If there's someone waiting who has positive credit, ..."

 -George

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