diff --git a/runtime/Makefile b/runtime/Makefile
index f0816a8..c8d4de4 100644
--- a/runtime/Makefile
+++ b/runtime/Makefile
@@ -16,6 +16,7 @@ CFLAGS += -D_GNU_SOURCE
 #CFLAGS += -DNOSTDIO
 #CFLAGS += -DSTANDALONE
 CFLAGS += -DUSE_UVIO
+#CFLAGS += -DUSE_HTTP_UVIO -DUSE_HTTP_SYNC
 CFLAGS += -DSBOX_SCALE_ALLOC
 #CFLAGS += -DUSE_SYSCALL
 #CFLAGS += -DPREEMPT_DISABLE
diff --git a/runtime/include/http.h b/runtime/include/http.h
index 04b9e4d..ac0fd09 100644
--- a/runtime/include/http.h
+++ b/runtime/include/http.h
@@ -4,6 +4,7 @@
 #include <http_parser.h>
 #include <types.h>
 #include <uv.h>
+#include <sys/uio.h>
 
 /* all in-memory ptrs.. don't mess around with that! */
 struct http_header {
@@ -34,7 +35,11 @@ struct http_response {
 	int bodylen;
 	char *status;
 	int stlen;
+#ifdef USE_HTTP_UVIO
 	uv_buf_t bufs[HTTP_HEADERS_MAX * 2 + 3]; //max headers, one line for status code, remaining for body!
+#else
+	struct iovec bufs[HTTP_HEADERS_MAX * 2 + 3];
+#endif
 };
 
 #endif /* SFRT_HTTP_H */
diff --git a/runtime/include/http_api.h b/runtime/include/http_api.h
index ba7c493..2e99a0d 100644
--- a/runtime/include/http_api.h
+++ b/runtime/include/http_api.h
@@ -8,7 +8,7 @@ int http_request_parse_sb(struct sandbox *s, size_t l);
 int http_response_header_set_sb(struct sandbox *s, char *h, int len);
 int http_response_body_set_sb(struct sandbox *s, char *body, int len);
 int http_response_status_set_sb(struct sandbox *s, char *status, int len);
-int http_response_uv_sb(struct sandbox *s);
+int http_response_vector_sb(struct sandbox *s);
 
 void http_init(void);
 
@@ -37,9 +37,9 @@ http_response_status_set(char *status, int len)
 }
 
 static inline int
-http_response_uv(void)
+http_response_vector(void)
 {
-	return http_response_uv_sb(sandbox_current());
+	return http_response_vector_sb(sandbox_current());
 }
 
 static inline int
diff --git a/runtime/include/sandbox.h b/runtime/include/sandbox.h
index e4b99c0..5e348d2 100644
--- a/runtime/include/sandbox.h
+++ b/runtime/include/sandbox.h
@@ -193,9 +193,12 @@ sandbox_args(void)
 
 //void sandbox_run(struct sandbox *s);
 void *sandbox_run_func(void *data);
-struct sandbox *sandbox_schedule(void);
+struct sandbox *sandbox_schedule(int interrupt);
 void sandbox_block(void);
 void sandbox_wakeup(sandbox_t *sb);
+// called in sandbox_entry() before and after fn() execution 
+// for http request/response processing using uvio
+void sandbox_block_http(void);
 void sandbox_response(void);
 
 // should be the entry-point for each sandbox so it can do per-sandbox mem/etc init.
diff --git a/runtime/include/types.h b/runtime/include/types.h
index b2e34a6..27d5839 100644
--- a/runtime/include/types.h
+++ b/runtime/include/types.h
@@ -116,7 +116,7 @@ typedef enum {
 #define JSON_ELE_MAX 16
 
 // FIXME: some naive work-stealing here..
-#define SBOX_PULL_MAX 16
+#define SBOX_PULL_MAX 1
 
 #define SBOX_MAX_OPEN 32
 #define SBOX_PREOPEN_MAGIC (707707707) // reads lol lol lol upside down
diff --git a/runtime/src/http.c b/runtime/src/http.c
index 17a3fb4..806de88 100644
--- a/runtime/src/http.c
+++ b/runtime/src/http.c
@@ -163,12 +163,13 @@ http_response_status_set_sb(struct sandbox *c, char *status, int len)
 }
 
 int
-http_response_uv_sb(struct sandbox *c)
+http_response_vector_sb(struct sandbox *c)
 {
 	int nb = 0;
 #ifndef STANDALONE
 	struct http_response *r = &c->rsi;
 
+#ifdef USE_HTTP_UVIO
 
 	r->bufs[nb] = uv_buf_init(r->status, r->stlen);
 	nb++;
@@ -183,6 +184,27 @@ http_response_uv_sb(struct sandbox *c)
 		r->bufs[nb] = uv_buf_init(r->status + r->stlen - 2, 2); //for crlf
 		nb++;
 	}
+#else
+	r->bufs[nb].iov_base = r->status;
+	r->bufs[nb].iov_len  = r->stlen;
+	nb++;
+
+	for (int i = 0; i < r->nheaders; i++) {
+		r->bufs[nb].iov_base = r->headers[i].hdr;
+		r->bufs[nb].iov_len  = r->headers[i].len;
+		nb++;
+	}
+
+	if (r->body) {
+		r->bufs[nb].iov_base = r->body;
+		r->bufs[nb].iov_len  = r->bodylen;
+		nb++;
+
+		r->bufs[nb].iov_base = r->status + r->stlen - 2;
+		r->bufs[nb].iov_len  = 2;
+		nb++;
+	}
+#endif
 #endif
 	
 	return nb;
diff --git a/runtime/src/runtime.c b/runtime/src/runtime.c
index 7ff4347..4683eda 100644
--- a/runtime/src/runtime.c
+++ b/runtime/src/runtime.c
@@ -87,10 +87,12 @@ sandbox_io_nowait(void)
 }
 
 struct sandbox *
-sandbox_schedule(void)
+sandbox_schedule(int interrupt)
 {
 	struct sandbox *s = NULL;
 	if (ps_list_head_empty(&runq)) {
+		// this is in an interrupt context, don't steal work here!
+		if (interrupt) return NULL;
 		if (sandbox_pull() == 0) {
 			//debuglog("[null: null]\n");
 			return NULL;
@@ -130,7 +132,7 @@ sandbox_schedule_io(void)
 	if (!in_callback) sandbox_io_nowait();
 
 	softint_disable();
-	struct sandbox *s = sandbox_schedule();
+	struct sandbox *s = sandbox_schedule(0);
 	softint_enable();
 	assert(s == NULL || s->state == SANDBOX_RUNNABLE);
 
@@ -143,11 +145,12 @@ sandbox_wakeup(sandbox_t *s)
 #ifndef STANDALONE
 	softint_disable();
 	debuglog("[%p: %s]\n", s, s->mod->name);
-	// perhaps 2 lists in the sandbox to make sure sandbox is either in runlist or waitlist..
+	if (s->state != SANDBOX_BLOCKED) goto done;
 	assert(s->state == SANDBOX_BLOCKED);
 	assert(ps_list_singleton_d(s));
 	s->state = SANDBOX_RUNNABLE;
 	ps_list_head_append_d(&runq, s);
+done:
 	softint_enable();
 #endif
 }
@@ -156,13 +159,12 @@ void
 sandbox_block(void)
 {
 #ifndef STANDALONE
-	// perhaps 2 lists in the sandbox to make sure sandbox is either in runlist or waitlist..
 	assert(in_callback == 0);
 	softint_disable();
 	struct sandbox *c = sandbox_current();
 	ps_list_rem_d(c);
 	c->state = SANDBOX_BLOCKED;
-	struct sandbox *s = sandbox_schedule();
+	struct sandbox *s = sandbox_schedule(0);
 	debuglog("[%p: %s, %p: %s]\n", c, c->mod->name, s, s ? s->mod->name: "");
 	softint_enable();
 	sandbox_switch(s);
@@ -171,6 +173,24 @@ sandbox_block(void)
 #endif
 }
 
+void
+sandbox_block_http(void)
+{
+#ifdef USE_HTTP_UVIO
+#ifdef USE_HTTP_SYNC
+	// realistically, we're processing all async I/O on this core when a sandbox blocks on http processing, not great!
+	// if there is a way (TODO), perhaps RUN_ONCE and check if your I/O is processed, if yes, return
+	// else do async block!
+	uv_run(runtime_uvio(), UV_RUN_DEFAULT);
+#else
+	sandbox_block();
+#endif
+#else
+	assert(0);
+	//it should not be called if not using uvio for http
+#endif
+}
+
 void __attribute__((noinline)) __attribute__((noreturn))
 sandbox_switch_preempt(void)
 {
@@ -248,7 +268,7 @@ sandbox_exit(void)
 	sandbox_local_stop(curr);
 	curr->state = SANDBOX_RETURNED;
 	// free resources from "main function execution", as stack still in use. 
-	struct sandbox *n = sandbox_schedule();
+	struct sandbox *n = sandbox_schedule(0);
 	assert(n != curr);
 	softint_enable();
 	//sandbox_local_end(curr);
diff --git a/runtime/src/sandbox.c b/runtime/src/sandbox.c
index 4502ed6..b854d04 100644
--- a/runtime/src/sandbox.c
+++ b/runtime/src/sandbox.c
@@ -133,11 +133,11 @@ sandbox_client_request_get(void)
 	struct sandbox *curr = sandbox_current();
 
 	curr->rr_data_len = 0;
-#ifndef USE_UVIO
+#ifndef USE_HTTP_UVIO
 	int r = 0;
 	r = recv(curr->csock, (curr->req_resp_data), curr->mod->max_req_sz, 0);
 	if (r <= 0) {
-		perror("recv");
+		if (r < 0) perror("recv1");
 		return r;
 	}
 	while (r > 0) {
@@ -148,13 +148,13 @@ sandbox_client_request_get(void)
 
 		r = recv(curr->csock, (curr->req_resp_data + r), curr->mod->max_req_sz - r, 0);
 		if (r < 0) {
-			perror("recv");
+			perror("recv2");
 			return r;
 		}
 	}
 #else
 	int r = uv_read_start((uv_stream_t *)&curr->cuv, sb_alloc_callback, sb_read_callback);
-	sandbox_block();
+	sandbox_block_http();
 	if (curr->rr_data_len == 0) return 0;
 #endif
 
@@ -170,15 +170,6 @@ sandbox_client_response_set(void)
 #ifndef STANDALONE
 	struct sandbox *curr = sandbox_current();
 
-#ifndef USE_UVIO
-	strcpy(curr->req_resp_data + curr->rr_data_len, "HTTP/1.1 200 OK\r\n");
-
-	// TODO: response set in req_resp_data
-	curr->rr_data_len += strlen("HTTP/1.1 200 OK\r\n");
-
-	int r = send(curr->csock, curr->req_resp_data, curr->rr_data_len, 0);
-	if (r < 0) perror("send");
-#else
 	int bodylen = curr->rr_data_len;
 	if (bodylen > 0) {
 		http_response_body_set(curr->req_resp_data, bodylen);
@@ -217,10 +208,14 @@ sandbox_client_response_set(void)
 	curr->rr_data_len += strlen("HTTP/1.1 200 OK\r\n");
 
 	http_response_status_set(st, strlen("HTTP/1.1 200 OK\r\n"));
+	int n = http_response_vector();
+#ifndef USE_HTTP_UVIO
+	int r = writev(curr->csock, curr->rsi.bufs, n);
+	if (r < 0) perror("writev");
+#else
 	uv_write_t req = { .data = curr, };
-	int n = http_response_uv();
 	int r = uv_write(&req, (uv_stream_t *)&curr->cuv, curr->rsi.bufs, n, sb_write_callback);
-	sandbox_block();
+	sandbox_block_http();
 #endif
 	return r;
 #else
@@ -253,7 +248,11 @@ sandbox_entry(void)
 #ifndef STANDALONE
 	http_parser_init(&curr->hp, HTTP_REQUEST);
 	curr->hp.data = curr;
-#ifdef USE_UVIO
+#ifdef USE_HTTP_UVIO
+#ifndef USE_UVIO
+	printf("UVIO not enabled!\n");
+	assert(0);
+#endif
 	int r = uv_tcp_init(runtime_uvio(), (uv_tcp_t *)&curr->cuv);
 	assert(r == 0);
 	curr->cuv.data = curr;
@@ -277,9 +276,9 @@ sandbox_entry(void)
 	}
 
 #ifndef STANDALONE
-#ifdef USE_UVIO
+#ifdef USE_HTTP_UVIO
 	uv_close((uv_handle_t *)&curr->cuv, sb_close_callback);
-	sandbox_block();
+	sandbox_block_http();
 #else
 	close(curr->csock);
 #endif
diff --git a/runtime/src/softint.c b/runtime/src/softint.c
index dff8011..bf3b50c 100644
--- a/runtime/src/softint.c
+++ b/runtime/src/softint.c
@@ -67,7 +67,7 @@ softint_alarm_schedule(void *u)
 	if (curr == NULL) goto done;
 	
 	// find a next sandbox to run..
-	struct sandbox *next = sandbox_schedule();
+	struct sandbox *next = sandbox_schedule(1);
 	if (next == NULL) goto done;
 	if (next == curr) goto done; // only this sandbox to schedule.. return to it!
 	// save the current sandbox, state from uc!