Index: benchmark/io/http/filecache.cfa
===================================================================
--- benchmark/io/http/filecache.cfa	(revision a5bc72ee443c0fd168c8da08611139c1ba7b46a4)
+++ benchmark/io/http/filecache.cfa	(revision d11d6ebdac4eb4d61f52ccf8176d113768ef6216)
@@ -73,4 +73,6 @@
 	cache_line * entries;
 	size_t size;
+	int * rawfds;
+	int nfds;
 } file_cache;
 
@@ -98,5 +100,5 @@
 }
 
-int put_file( cache_line & entry ) {
+int put_file( cache_line & entry, int fd ) {
 	uint32_t idx = murmur3_32( (const uint8_t *)entry.file, strlen(entry.file), options.file_cache.hash_seed ) % file_cache.size;
 
@@ -108,4 +110,5 @@
 
 	file_cache.entries[idx] = entry;
+	file_cache.entries[idx].fd = fd;
 	return i > 0 ? 1 : 0;
 }
@@ -121,6 +124,5 @@
 	size_t fcount = 0;
 	size_t fsize = 16;
-	cache_line * raw = 0p;
-	raw = alloc(raw, fsize, true);
+	cache_line * raw = alloc(fsize);
 	// Step 1 get a dense array of all files
 	int walk(const char *fpath, const struct stat *sb, int typeflag) {
@@ -131,5 +133,5 @@
 		if(fcount > fsize) {
 			fsize *= 2;
-			raw = alloc(raw, fsize, true);
+			raw = alloc(fsize, raw`realloc);
 		}
 
@@ -162,8 +164,21 @@
 	file_cache.entries = anew(file_cache.size);
 
+	if(options.file_cache.fixed_fds) {
+		file_cache.nfds   = fcount;
+		file_cache.rawfds = alloc(fcount);
+	}
+
 	// Step 3 fill the cache
 	int conflicts = 0;
 	for(i; fcount) {
-		conflicts += put_file( raw[i] );
+		int fd;
+		if(options.file_cache.fixed_fds) {
+			file_cache.rawfds[i] = raw[i].fd;
+			fd = i;
+		}
+		else {
+			fd = raw[i].fd;
+		}
+		conflicts += put_file( raw[i], fd );
 	}
 	printf("Filled cache from path \"%s\" with %zu files\n", path, fcount);
@@ -197,5 +212,7 @@
 	}
 
-	return [aalloc(extra), 0];
+	size_t s = file_cache.nfds + extra;
+	int * data = alloc(s, file_cache.rawfds`realloc);
+	return [data, file_cache.nfds];
 }
 
Index: benchmark/io/http/main.cfa
===================================================================
--- benchmark/io/http/main.cfa	(revision a5bc72ee443c0fd168c8da08611139c1ba7b46a4)
+++ benchmark/io/http/main.cfa	(revision d11d6ebdac4eb4d61f52ccf8176d113768ef6216)
@@ -12,4 +12,5 @@
 #include <kernel.hfa>
 #include <stats.hfa>
+#include <time.hfa>
 #include <thread.hfa>
 
@@ -18,4 +19,10 @@
 #include "options.hfa"
 #include "worker.hfa"
+
+extern void register_fixed_files( cluster &, int *, unsigned count );
+
+Duration default_preemption() {
+	return 0;
+}
 
 //=============================================================================================
@@ -84,5 +91,5 @@
 	// Run Server Cluster
 	{
-		cluster cl = { "Server Cluster", options.clopts.flags };
+		cluster cl = { "Server Cluster", options.clopts.params };
 		#if !defined(__CFA_NO_STATISTICS__)
 			print_stats_at_exit( cl, CFA_STATS_READY_Q | CFA_STATS_IO );
@@ -102,4 +109,8 @@
 		}
 
+		if(options.file_cache.fixed_fds) {
+			register_fixed_files(cl, fds, pipe_off);
+		}
+
 		{
 			ServerProc procs[options.clopts.nprocs];
@@ -107,9 +118,10 @@
 				Worker workers[options.clopts.nworkers];
 				for(i; options.clopts.nworkers) {
-					if( options.file_cache.fixed_fds ) {
-						workers[i].pipe[0] = pipe_off + (i * 2) + 0;
-						workers[i].pipe[1] = pipe_off + (i * 2) + 1;
-					}
-					else {
+					// if( options.file_cache.fixed_fds ) {
+					// 	workers[i].pipe[0] = pipe_off + (i * 2) + 0;
+					// 	workers[i].pipe[1] = pipe_off + (i * 2) + 1;
+					// }
+					// else
+					{
 						workers[i].pipe[0] = fds[pipe_off + (i * 2) + 0];
 						workers[i].pipe[1] = fds[pipe_off + (i * 2) + 1];
Index: benchmark/io/http/options.cfa
===================================================================
--- benchmark/io/http/options.cfa	(revision a5bc72ee443c0fd168c8da08611139c1ba7b46a4)
+++ benchmark/io/http/options.cfa	(revision d11d6ebdac4eb4d61f52ccf8176d113768ef6216)
@@ -39,5 +39,4 @@
 
 const char * parse_options( int argc, char * argv[] ) {
-	bool uthrdpo = false;
 	bool subthrd = false;
 	bool eagrsub = false;
@@ -57,5 +56,4 @@
 		{'C', "cache-size",     "Size of the cache to use, if set to small, will uses closes power of 2", options.file_cache.size },
 		{'l', "list-files",     "List the files in the specified path and exit", options.file_cache.list, parse_settrue },
-		{'u', "userthread",     "If set, cluster uses user-thread to poll I/O", uthrdpo, parse_settrue },
 		{'s', "submitthread",   "If set, cluster uses polling thread to submit I/O", subthrd, parse_settrue },
 		{'e', "eagersubmit",    "If set, cluster submits I/O eagerly but still aggregates submits", eagrsub, parse_settrue},
@@ -71,15 +69,6 @@
 	parse_args( argc, argv, opt, opt_cnt, "[OPTIONS]... [PATH]\ncforall http server", left );
 
-	if( uthrdpo ) {
-		options.clopts.flags |= CFA_CLUSTER_IO_POLLER_USER_THREAD;
-	}
-
-	if( subthrd ) {
-		options.clopts.flags |= CFA_CLUSTER_IO_POLLER_THREAD_SUBMITS;
-	}
-
-	if( eagrsub ) {
-		options.clopts.flags |= CFA_CLUSTER_IO_EAGER_SUBMITS;
-	}
+	options.clopts.params.poller_submits = subthrd;
+	options.clopts.params.eager_submits  = eagrsub;
 
 	if( fixedfd ) {
@@ -88,14 +77,14 @@
 
 	if( sqkpoll ) {
-		options.clopts.flags |= CFA_CLUSTER_IO_KERNEL_POLL_SUBMITS;
+		options.clopts.params.poll_submit = true;
 		options.file_cache.fixed_fds = true;
 	}
 
 	if( iokpoll ) {
-		options.clopts.flags |= CFA_CLUSTER_IO_KERNEL_POLL_COMPLETES;
+		options.clopts.params.poll_complete = true;
 		options.file_cache.open_flags |= O_DIRECT;
 	}
 
-	options.clopts.flags |= (sublen << CFA_CLUSTER_IO_BUFFLEN_OFFSET);
+	options.clopts.params.num_ready = sublen;
 
 	if( left[0] == 0p ) { return "."; }
Index: benchmark/io/http/options.hfa
===================================================================
--- benchmark/io/http/options.hfa	(revision a5bc72ee443c0fd168c8da08611139c1ba7b46a4)
+++ benchmark/io/http/options.hfa	(revision d11d6ebdac4eb4d61f52ccf8176d113768ef6216)
@@ -2,4 +2,6 @@
 
 #include <stdint.h>
+
+#include <kernel.hfa>
 
 struct cluster;
@@ -23,5 +25,5 @@
 		int nprocs;
 		int nworkers;
-		int flags;
+		io_context_params params;
 		int chan_size;
 		bool procstats;
Index: benchmark/io/http/protocol.cfa
===================================================================
--- benchmark/io/http/protocol.cfa	(revision a5bc72ee443c0fd168c8da08611139c1ba7b46a4)
+++ benchmark/io/http/protocol.cfa	(revision d11d6ebdac4eb4d61f52ccf8176d113768ef6216)
@@ -11,9 +11,10 @@
 extern "C" {
       int snprintf ( char * s, size_t n, const char * format, ... );
+	#include <linux/io_uring.h>
 }
 #include <string.h>
-
 #include <errno.h>
 
+#include "options.hfa"
 
 const char * http_msgs[] = {
@@ -74,6 +75,6 @@
 	READ:
 	for() {
-		int ret = cfa_read(fd, it, count);
-		if(ret == 0 ) return [OK200, true, 0p, 0];
+		int ret = cfa_read(fd, (void*)it, count, 0, -1`s, 0p, 0p);
+		if(ret == 0 ) return [OK200, true, 0, 0];
 		if(ret < 0 ) {
 			if( errno == EAGAIN || errno == EWOULDBLOCK) continue READ;
@@ -88,5 +89,5 @@
 		count -= ret;
 
-		if( count < 1 ) return [E414, false, 0p, 0];
+		if( count < 1 ) return [E414, false, 0, 0];
 	}
 
@@ -95,5 +96,5 @@
 	it = buffer;
 	int ret = memcmp(it, "GET /", 5);
-	if( ret != 0 ) return [E400, false, 0p, 0];
+	if( ret != 0 ) return [E400, false, 0, 0];
 	it += 5;
 
@@ -106,5 +107,5 @@
 	ssize_t ret;
 	SPLICE1: while(count > 0) {
-		ret = cfa_splice(ans_fd, &offset, pipe[1], 0p, count, SPLICE_F_MOVE | SPLICE_F_MORE);
+		ret = cfa_splice(ans_fd, &offset, pipe[1], 0p, count, SPLICE_F_MOVE | SPLICE_F_MORE, 0, -1`s, 0p, 0p);
 		if( ret < 0 ) {
 			if( errno != EAGAIN && errno != EWOULDBLOCK) continue SPLICE1;
@@ -116,5 +117,5 @@
 		size_t in_pipe = ret;
 		SPLICE2: while(in_pipe > 0) {
-			ret = cfa_splice(pipe[0], 0p, fd, 0p, in_pipe, SPLICE_F_MOVE | SPLICE_F_MORE);
+			ret = cfa_splice(pipe[0], 0p, fd, 0p, in_pipe, SPLICE_F_MOVE | SPLICE_F_MORE, 0, -1`s, 0p, 0p);
 			if( ret < 0 ) {
 				if( errno != EAGAIN && errno != EWOULDBLOCK) continue SPLICE2;
Index: benchmark/io/http/worker.cfa
===================================================================
--- benchmark/io/http/worker.cfa	(revision a5bc72ee443c0fd168c8da08611139c1ba7b46a4)
+++ benchmark/io/http/worker.cfa	(revision d11d6ebdac4eb4d61f52ccf8176d113768ef6216)
@@ -96,5 +96,5 @@
 void main( Acceptor & this ) {
 	for() {
-		int ret = cfa_accept4( this.[sockfd, addr, addrlen, flags] );
+		int ret = cfa_accept4( this.[sockfd, addr, addrlen, flags], 0, -1`s, 0p, 0p );
 		if(ret < 0) {
 			if( errno == ECONNABORTED ) break;