In Solaris, threads are frequently relocated. The data associated with a relocated thread have to be moved from the cache of the old processor to the new processor. In order to avoid poor memory performance due to thread relocation, threads can be bound to processors-static scheduling. Finding a static schedule which results in maximum speedup is NP-hard. It is even difficult to determine if a static schedule is close to the optimal case or not. Here, a technique for predicting the speedup of multithreaded Solaris programs is presented. Based on an existing theoretical result, a lower bound on the maximal speedup is also obtained. The predicted speedup and the bound are based on recordings from a single-processor execution. When comparing the predictions with the real speedup using a multiprocessor with eight processors, we see that the predictions are very good. By comparing the speedup of a static schedule with the bound, we see that it is worthwhile to look for other schedules. (C) 1999 Academic Press.