kernel: reuse a single allocation for all vfs_requests of a process

$ iostress 32 512 0 > /vtty # before
512 calls, 0 bytes. avg 121133
$ iostress 32 512 0 > /vtty # after
512 calls, 0 bytes. avg 103540

103540/121133 = ~85%

I think the tiny bit of added complexity is worth it here.

1 files changed, 7 insertions, 2 deletions

diff --git a/src/kernel/proc.c b/src/kernel/proc.c
index a8cf303..e7a5ed6 100644
--- a/src/kernel/proc.c
+++ b/src/kernel/proc.c
@@ -114,8 +114,13 @@ void process_kill(struct process *p, int ret) {
 			p->controlled = NULL;
 		}
 
-		if (p->state == PS_WAITS4FS)
-			p->waits4fs.req->caller = NULL;
+		if (p->state == PS_WAITS4FS) {
+			assert(p->reqslot);
+			p->reqslot->caller = NULL; /* transfer ownership */
+			p->reqslot = NULL;
+		} else if (p->reqslot) {
+			kfree(p->reqslot);
+		}
 
 		if (p->state == PS_WAITS4PIPE) {
 			struct process **iter = &p->waits4pipe.pipe->pipe.queued;