diff options
| -rw-r--r-- | libports/manage-multithread.c | 30 |
1 files changed, 16 insertions, 14 deletions
diff --git a/libports/manage-multithread.c b/libports/manage-multithread.c index 309b3038..035cd38d 100644 --- a/libports/manage-multithread.c +++ b/libports/manage-multithread.c @@ -26,15 +26,27 @@ #include <mach/thread_info.h> #include <mach/thread_switch.h> -/* A very high priority is assigned to reduce thread storms in core servers. */ #define THREAD_PRI 2 +/* XXX To reduce starvation, the priority of new threads is initially + depressed. This helps already existing threads complete their job and be + recycled to handle new messages. The duration of this depression is made + a function of the total number of threads because more threads imply + more contention, and the priority of threads blocking on a contended spin + lock is also implicitely depressed. + + Then, if permitted, a greater priority is requested to further decrease + the need for additional threads. */ static void -adjust_priority (void) +adjust_priority (unsigned int totalthreads) { mach_port_t host_priv, self, pset, pset_priv; + unsigned int t; error_t err; + t = 10 + (((totalthreads - 1) / 100) + 1) * 10; + thread_switch (MACH_PORT_NULL, SWITCH_OPTION_DEPRESS, t); + self = MACH_PORT_NULL; err = get_privileged_ports (&host_priv, NULL); @@ -162,18 +174,8 @@ ports_manage_port_operations_multithread (struct port_bucket *bucket, int timeout; error_t err; - /* XXX To reduce starvation, the priority of new threads is initially - depressed. This helps already existing threads complete their job - and be recycled to handle new messages. The duration of this - depression is made a function of the total number of threads because - more threads implies more contention, and the priority of threads - blocking on a contented spin lock is also implicitely depressed. - The lock isn't needed, since an approximation is sufficient. */ - timeout = (((totalthreads - 1) / 100) + 1) * 10; - thread_switch (MACH_PORT_NULL, SWITCH_OPTION_DEPRESS, timeout); - - /* XXX Give servers a greater priority when possible. */ - adjust_priority (); + /* No need to lock as an approximation is sufficient. */ + adjust_priority (totalthreads); if (hook) (*hook) (); |