diff --git a/Makefile b/Makefile
index 8a8cd180..65afb203 100644
--- a/Makefile
+++ b/Makefile
@@ -1,15 +1,15 @@
 BLOCKSTORE_OBJS := allocator.o blockstore.o blockstore_init.o blockstore_open.o blockstore_journal.o blockstore_read.o \
-	blockstore_write.o blockstore_sync.o blockstore_stable.o blockstore_flush.o crc32c.o ringloop.o
+	blockstore_write.o blockstore_sync.o blockstore_stable.o blockstore_flush.o crc32c.o ringloop.o timerfd_interval.o
 all: $(BLOCKSTORE_OBJS) test test_blockstore libfio_blockstore.so
 clean:
 	rm -f *.o
 crc32c.o: crc32c.c
 	g++ -fPIC -c -o $@ $<
-%.o: %.cpp allocator.h blockstore_flush.h blockstore.h blockstore_init.h blockstore_journal.h crc32c.h ringloop.h xor.h
+%.o: %.cpp allocator.h blockstore_flush.h blockstore.h blockstore_init.h blockstore_journal.h crc32c.h ringloop.h xor.h timerfd_interval.h
 	g++ -g -Wall -Wno-sign-compare -Wno-parentheses -fPIC -c -o $@ $<
 test: test.cpp
 	g++ -g -O3 -o test -luring test.cpp
 test_blockstore: $(BLOCKSTORE_OBJS) test_blockstore.cpp
 	g++ -g -o test_blockstore -luring test_blockstore.cpp $(BLOCKSTORE_OBJS)
 libfio_blockstore.so: fio_engine.cpp $(BLOCKSTORE_OBJS)
-	g++ -Wno-pointer-arith -fPIC -shared -luring -o libfio_blockstore.so fio_engine.cpp $(BLOCKSTORE_OBJS)
+	g++ -g -Wno-pointer-arith -fPIC -shared -luring -o libfio_blockstore.so fio_engine.cpp $(BLOCKSTORE_OBJS)
diff --git a/fio_engine.cpp b/fio_engine.cpp
index 7034d37f..f58ca7f1 100644
--- a/fio_engine.cpp
+++ b/fio_engine.cpp
@@ -43,7 +43,7 @@ static int bs_setup(struct thread_data *td)
     int r;
     //int64_t size;
 
-    bsd = (bs_data*)calloc(1, sizeof(*bsd));
+    bsd = new bs_data;
     if (!bsd)
     {
         td_verror(td, errno, "calloc");
@@ -71,7 +71,7 @@ static void bs_cleanup(struct thread_data *td)
     if (bsd)
     {
         
-        free(bsd);
+        delete bsd;
     }
 }
 
@@ -88,9 +88,12 @@ static int bs_init(struct thread_data *td)
     config["data_device"] = "./test_data.bin";
     bsd->ringloop = new ring_loop_t(512);
     bsd->bs = new blockstore(config, bsd->ringloop);
-    while (!bsd->bs->is_started())
+    while (1)
     {
         bsd->ringloop->loop();
+        if (bsd->bs->is_started())
+            break;
+        bsd->ringloop->wait();
     }
 
     log_info("fio: blockstore initialized\n");
@@ -122,8 +125,9 @@ static enum fio_q_status bs_queue(struct thread_data *td, struct io_u *io_u)
         };
         op->offset = io_u->offset % bsd->bs->block_size;
         op->len = io_u->xfer_buflen;
-        op->callback = [&](blockstore_operation *op)
+        op->callback = [io_u](blockstore_operation *op)
         {
+            bs_data *bsd = (bs_data*)io_u->engine_data;
             bsd->completed.push_back(io_u);
             delete op;
         };
@@ -137,16 +141,18 @@ static enum fio_q_status bs_queue(struct thread_data *td, struct io_u *io_u)
         };
         op->offset = io_u->offset % bsd->bs->block_size;
         op->len = io_u->xfer_buflen;
-        op->callback = [&](blockstore_operation *op)
+        op->callback = [io_u](blockstore_operation *op)
         {
+            bs_data *bsd = (bs_data*)io_u->engine_data;
             bsd->completed.push_back(io_u);
             delete op;
         };
         break;
     case DDIR_SYNC:
         op->flags = OP_SYNC;
-        op->callback = [&](blockstore_operation *op)
+        op->callback = [io_u](blockstore_operation *op)
         {
+            bs_data *bsd = (bs_data*)io_u->engine_data;
             if (bsd->bs->unstable_writes.size() > 0)
             {
                 op->flags = OP_STABLE;
@@ -162,8 +168,9 @@ static enum fio_q_status bs_queue(struct thread_data *td, struct io_u *io_u)
                     };
                 }
                 bsd->bs->enqueue_op(op);
-                op->callback = [&](blockstore_operation *op)
+                op->callback = [io_u](blockstore_operation *op)
                 {
+                    bs_data *bsd = (bs_data*)io_u->engine_data;
                     bsd->completed.push_back(io_u);
                     obj_ver_id *vers = (obj_ver_id*)op->buf;
                     delete[] vers;
@@ -192,9 +199,12 @@ static int bs_getevents(struct thread_data *td, unsigned int min, unsigned int m
 {
     bs_data *bsd = (bs_data*)td->io_ops_data;
     // FIXME timeout
-    while (bsd->completed.size() < min)
+    while (true)
     {
         bsd->ringloop->loop();
+        if (bsd->completed.size() >= min)
+            break;
+        bsd->ringloop->wait();
     }
     return bsd->completed.size();
 }
diff --git a/ringloop.cpp b/ringloop.cpp
index cf495fa0..509366c2 100644
--- a/ringloop.cpp
+++ b/ringloop.cpp
@@ -62,5 +62,4 @@ void ring_loop_t::loop()
             consumers[i].loop();
         }
     } while (loop_again);
-    io_uring_wait_cqe(&ring, &cqe);
 }
diff --git a/ringloop.h b/ringloop.h
index 3701cc7a..8201a1e8 100644
--- a/ringloop.h
+++ b/ringloop.h
@@ -142,4 +142,9 @@ public:
     {
         return io_uring_submit(&ring);
     }
+    inline int wait()
+    {
+        struct io_uring_cqe *cqe;
+        return io_uring_wait_cqe(&ring, &cqe);
+    }
 };
diff --git a/test_blockstore.cpp b/test_blockstore.cpp
index 8afdf0cf..fdd5ea58 100644
--- a/test_blockstore.cpp
+++ b/test_blockstore.cpp
@@ -1,75 +1,7 @@
-#include <sys/timerfd.h>
-#include <sys/poll.h>
 #include <iostream>
+#include "timerfd_interval.h"
 #include "blockstore.h"
 
-class timerfd_interval
-{
-    int wait_state;
-    int timerfd;
-    int status;
-    ring_loop_t *ringloop;
-    ring_consumer_t consumer;
-    std::function<void(void)> callback;
-public:
-    timerfd_interval(ring_loop_t *ringloop, int seconds, std::function<void(void)> cb)
-    {
-        wait_state = 0;
-        timerfd = timerfd_create(CLOCK_MONOTONIC, TFD_NONBLOCK);
-        if (timerfd < 0)
-        {
-            throw std::runtime_error(std::string("timerfd_create: ") + strerror(errno));
-        }
-        struct itimerspec exp = {
-            .it_interval = { seconds, 0 },
-            .it_value = { seconds, 0 },
-        };
-        if (timerfd_settime(timerfd, 0, &exp, NULL))
-        {
-            throw std::runtime_error(std::string("timerfd_settime: ") + strerror(errno));
-        }
-        consumer.loop = [this]() { loop(); };
-        ringloop->register_consumer(consumer);
-        this->ringloop = ringloop;
-        this->callback = cb;
-    }
-
-    ~timerfd_interval()
-    {
-        ringloop->unregister_consumer(consumer);
-        close(timerfd);
-    }
-
-    void loop()
-    {
-        if (wait_state == 1)
-        {
-            return;
-        }
-        struct io_uring_sqe *sqe = ringloop->get_sqe();
-        if (!sqe)
-        {
-            wait_state = 0;
-            return;
-        }
-        struct ring_data_t *data = ((ring_data_t*)sqe->user_data);
-        my_uring_prep_poll_add(sqe, timerfd, POLLIN);
-        data->callback = [&](ring_data_t *data)
-        {
-            if (data->res < 0)
-            {
-                throw std::runtime_error(std::string("waiting for timer failed: ") + strerror(-data->res));
-            }
-            uint64_t n;
-            read(timerfd, &n, 8);
-            wait_state = 0;
-            callback();
-        };
-        wait_state = 1;
-        ringloop->submit();
-    }
-};
-
 int main(int narg, char *args[])
 {
     spp::sparse_hash_map<std::string, std::string> config;
@@ -141,6 +73,7 @@ int main(int narg, char *args[])
     while (1)
     {
         ringloop->loop();
+        ringloop->wait();
     }
     delete bs;
     delete ringloop;
diff --git a/timerfd_interval.cpp b/timerfd_interval.cpp
new file mode 100644
index 00000000..a7903b5f
--- /dev/null
+++ b/timerfd_interval.cpp
@@ -0,0 +1,61 @@
+#include <sys/timerfd.h>
+#include <sys/poll.h>
+#include <unistd.h>
+#include "timerfd_interval.h"
+
+timerfd_interval::timerfd_interval(ring_loop_t *ringloop, int seconds, std::function<void(void)> cb)
+{
+    wait_state = 0;
+    timerfd = timerfd_create(CLOCK_MONOTONIC, TFD_NONBLOCK);
+    if (timerfd < 0)
+    {
+        throw std::runtime_error(std::string("timerfd_create: ") + strerror(errno));
+    }
+    struct itimerspec exp = {
+        .it_interval = { seconds, 0 },
+        .it_value = { seconds, 0 },
+    };
+    if (timerfd_settime(timerfd, 0, &exp, NULL))
+    {
+        throw std::runtime_error(std::string("timerfd_settime: ") + strerror(errno));
+    }
+    consumer.loop = [this]() { loop(); };
+    ringloop->register_consumer(consumer);
+    this->ringloop = ringloop;
+    this->callback = cb;
+}
+
+timerfd_interval::~timerfd_interval()
+{
+    ringloop->unregister_consumer(consumer);
+    close(timerfd);
+}
+
+void timerfd_interval::loop()
+{
+    if (wait_state == 1)
+    {
+        return;
+    }
+    struct io_uring_sqe *sqe = ringloop->get_sqe();
+    if (!sqe)
+    {
+        wait_state = 0;
+        return;
+    }
+    struct ring_data_t *data = ((ring_data_t*)sqe->user_data);
+    my_uring_prep_poll_add(sqe, timerfd, POLLIN);
+    data->callback = [&](ring_data_t *data)
+    {
+        if (data->res < 0)
+        {
+            throw std::runtime_error(std::string("waiting for timer failed: ") + strerror(-data->res));
+        }
+        uint64_t n;
+        read(timerfd, &n, 8);
+        wait_state = 0;
+        callback();
+    };
+    wait_state = 1;
+    ringloop->submit();
+}
diff --git a/timerfd_interval.h b/timerfd_interval.h
new file mode 100644
index 00000000..84d9587c
--- /dev/null
+++ b/timerfd_interval.h
@@ -0,0 +1,17 @@
+#pragma once
+
+#include "ringloop.h"
+
+class timerfd_interval
+{
+    int wait_state;
+    int timerfd;
+    int status;
+    ring_loop_t *ringloop;
+    ring_consumer_t consumer;
+    std::function<void(void)> callback;
+public:
+    timerfd_interval(ring_loop_t *ringloop, int seconds, std::function<void(void)> cb);
+    ~timerfd_interval();
+    void loop();
+};