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Indirect-to-direct-scheduling experiment

This commit is contained in:
Tony Garnock-Jones 2011-01-05 10:38:37 -05:00
parent 098b690e4d
commit 76280ef51b
2 changed files with 85 additions and 0 deletions
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11
TODO
View File

@ -14,3 +14,14 @@ last-value-cache type thing.
Website
- http://www.flickr.com/photos/elemishra/158211069/
Switch from indirect scheduling to direct scheduling
- before, on walk: 173kHz test1/test3
- after, no change. Probably because we only have a single thread
active in the system when running test1/test3, so every time some
work comes in, it baton-passes to the next guy in the chain. The
change *would* be an improvement but we have a separate worklist
(to process now) and runlist (to process after polling for events
once) so it always goes back to the scheduler because the worklist
is never longer than one.
- Revisit once we start testing multiple concurrent streams.

74
experiments/direct_scheduling.patch Normal file
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@ -0,0 +1,74 @@
diff --git a/harness.c b/harness.c
index 9c891b3..74061af 100644
--- a/harness.c
+++ b/harness.c
@@ -50,18 +50,38 @@ Process *current_process = NULL;
static ucontext_t scheduler;
static queue_t runlist = EMPTY_PROCESS_QUEUE;
static queue_t deadlist = EMPTY_PROCESS_QUEUE;
+static queue_t current_worklist = EMPTY_PROCESS_QUEUE;
static void enqueue_runlist(Process *p) {
p->state = PROCESS_RUNNING;
enqueue(&runlist, p);
}
+static void clean_dead_processes(void) {
+ Process *deadp;
+ while ((deadp = dequeue(&deadlist)) != NULL) {
+ free(deadp->stack_base);
+ free(deadp);
+ }
+}
+
static void schedule(void) {
- //info("schedule %p\n", current_process);
if (current_process == NULL) {
ICHECK(setcontext(&scheduler), "schedule setcontext");
} else {
- ICHECK(swapcontext(&current_process->context, &scheduler), "schedule swapcontext");
+ Process *current = current_process;
+ Process *target_process = dequeue(&current_worklist);
+ ucontext_t *target;
+
+ if (target_process == NULL) {
+ target = &scheduler;
+ } else {
+ target = &target_process->context;
+ current_process = target_process;
+ }
+
+ clean_dead_processes(); /* safe because we know we're not dead ourselves at this point */
+ ICHECK(swapcontext(&current->context, target), "schedule swapcontext");
}
}
@@ -255,14 +275,6 @@ void iohandle_settimeout(IOHandle *h, int timeout_read, int timeout_write) {
bufferevent_settimeout(h->io, timeout_read, timeout_write);
}
-static void clean_dead_processes(void) {
- Process *deadp;
- while ((deadp = dequeue(&deadlist)) != NULL) {
- free(deadp->stack_base);
- free(deadp);
- }
-}
-
void boot_harness(void) {
stdin_h = new_iohandle(0);
stdout_h = new_iohandle(1);
@@ -272,10 +284,10 @@ void boot_harness(void) {
while (1) {
while (runlist.count) {
- queue_t work = runlist;
+ current_worklist = runlist;
runlist = EMPTY_PROCESS_QUEUE;
- //info("Processing %d jobs\n", work.count);
- while ((current_process = dequeue(&work)) != NULL) {
+ //info("Processing %d jobs\n", current_worklist.count);
+ while ((current_process = dequeue(&current_worklist)) != NULL) {
//info("entering %p\n", current_process);
ICHECK(swapcontext(&scheduler, &current_process->context), "boot_harness swapcontext");
clean_dead_processes();