diff --git a/src/blockstore/blockstore.cpp b/src/blockstore/blockstore.cpp
index 74e1c306..15ca8d35 100644
--- a/src/blockstore/blockstore.cpp
+++ b/src/blockstore/blockstore.cpp
@@ -6,7 +6,7 @@
 #include "blockstore_impl.h"
 #include "v1/impl.h"
 
-blockstore_i* blockstore_i::create(blockstore_config_t & config, ring_loop_t *ringloop, timerfd_manager_t *tfd)
+blockstore_i* blockstore_i::create(blockstore_config_t & config, ring_loop_i *ringloop, timerfd_manager_t *tfd)
 {
     auto meta_format = stoull_full(config["meta_format"]);
     if (meta_format == BLOCKSTORE_META_FORMAT_HEAP)
diff --git a/src/blockstore/blockstore.h b/src/blockstore/blockstore.h
index 222d2fee..536c1588 100644
--- a/src/blockstore/blockstore.h
+++ b/src/blockstore/blockstore.h
@@ -176,7 +176,7 @@ typedef std::map<std::string, std::string> blockstore_config_t;
 class __attribute__((visibility("default"))) blockstore_i
 {
 public:
-    static blockstore_i* create(blockstore_config_t & config, ring_loop_t *ringloop, timerfd_manager_t *tfd);
+    static blockstore_i* create(blockstore_config_t & config, ring_loop_i *ringloop, timerfd_manager_t *tfd);
 
     virtual ~blockstore_i() = default;
 
diff --git a/src/blockstore/blockstore_disk.cpp b/src/blockstore/blockstore_disk.cpp
index 8e7d8fc2..726dc485 100644
--- a/src/blockstore/blockstore_disk.cpp
+++ b/src/blockstore/blockstore_disk.cpp
@@ -102,6 +102,15 @@ void blockstore_disk_t::parse_config(std::map<std::string, std::string> & config
     disable_data_fsync = config["disable_data_fsync"] == "true" || config["disable_data_fsync"] == "1" || config["disable_data_fsync"] == "yes";
     disable_meta_fsync = config["disable_meta_fsync"] == "true" || config["disable_meta_fsync"] == "1" || config["disable_meta_fsync"] == "yes";
     disable_journal_fsync = config["disable_journal_fsync"] == "true" || config["disable_journal_fsync"] == "1" || config["disable_journal_fsync"] == "yes";
+    if (mock_mode)
+    {
+        data_device_size = parse_size(config["data_device_size"]);
+        data_device_sect = parse_size(config["data_device_sect"]);
+        meta_device_size = parse_size(config["meta_device_size"]);
+        meta_device_sect = parse_size(config["meta_device_sect"]);
+        journal_device_size = parse_size(config["journal_device_size"]);
+        journal_device_sect = parse_size(config["journal_device_sect"]);
+    }
     // Validate
     if (!data_block_size)
     {
@@ -328,12 +337,15 @@ static int bs_openmode(const std::string & mode)
 
 void blockstore_disk_t::open_data()
 {
-    data_fd = open(data_device.c_str(), bs_openmode(data_io) | O_RDWR);
+    data_fd = mock_mode ? MOCK_DATA_FD : open(data_device.c_str(), bs_openmode(data_io) | O_RDWR);
     if (data_fd == -1)
     {
         throw std::runtime_error("Failed to open data device "+data_device+": "+std::string(strerror(errno)));
     }
-    check_size(data_fd, &data_device_size, &data_device_sect, "data device");
+    if (!mock_mode)
+    {
+        check_size(data_fd, &data_device_size, &data_device_sect, "data device");
+    }
     if (disk_alignment % data_device_sect)
     {
         throw std::runtime_error(
@@ -345,7 +357,7 @@ void blockstore_disk_t::open_data()
     {
         throw std::runtime_error("data_offset exceeds device size = "+std::to_string(data_device_size));
     }
-    if (!disable_flock && flock(data_fd, LOCK_EX|LOCK_NB) != 0)
+    if (!mock_mode && !disable_flock && flock(data_fd, LOCK_EX|LOCK_NB) != 0)
     {
         throw std::runtime_error(std::string("Failed to lock data device: ") + strerror(errno));
     }
@@ -355,17 +367,20 @@ void blockstore_disk_t::open_meta()
 {
     if (meta_device != data_device || meta_io != data_io)
     {
-        meta_fd = open(meta_device.c_str(), bs_openmode(meta_io) | O_RDWR);
+        meta_fd = mock_mode ? MOCK_META_FD : open(meta_device.c_str(), bs_openmode(meta_io) | O_RDWR);
         if (meta_fd == -1)
         {
             throw std::runtime_error("Failed to open metadata device "+meta_device+": "+std::string(strerror(errno)));
         }
-        check_size(meta_fd, &meta_device_size, &meta_device_sect, "metadata device");
+        if (!mock_mode)
+        {
+            check_size(meta_fd, &meta_device_size, &meta_device_sect, "metadata device");
+        }
         if (meta_offset >= meta_device_size)
         {
             throw std::runtime_error("meta_offset exceeds device size = "+std::to_string(meta_device_size));
         }
-        if (!disable_flock && meta_device != data_device && flock(meta_fd, LOCK_EX|LOCK_NB) != 0)
+        if (!mock_mode && !disable_flock && meta_device != data_device && flock(meta_fd, LOCK_EX|LOCK_NB) != 0)
         {
             throw std::runtime_error(std::string("Failed to lock metadata device: ") + strerror(errno));
         }
@@ -393,13 +408,20 @@ void blockstore_disk_t::open_journal()
 {
     if (journal_device != meta_device || journal_io != meta_io)
     {
-        journal_fd = open(journal_device.c_str(), bs_openmode(journal_io) | O_RDWR);
+        journal_fd = mock_mode ? MOCK_JOURNAL_FD : open(journal_device.c_str(), bs_openmode(journal_io) | O_RDWR);
         if (journal_fd == -1)
         {
             throw std::runtime_error("Failed to open journal device "+journal_device+": "+std::string(strerror(errno)));
         }
-        check_size(journal_fd, &journal_device_size, &journal_device_sect, "journal device");
-        if (!disable_flock && journal_device != meta_device && flock(journal_fd, LOCK_EX|LOCK_NB) != 0)
+        if (!mock_mode)
+        {
+            check_size(journal_fd, &journal_device_size, &journal_device_sect, "journal device");
+        }
+        if (journal_offset >= journal_device_size)
+        {
+            throw std::runtime_error("journal_offset exceeds device size = "+std::to_string(journal_device_size));
+        }
+        if (!mock_mode && !disable_flock && journal_device != meta_device && flock(journal_fd, LOCK_EX|LOCK_NB) != 0)
         {
             throw std::runtime_error(std::string("Failed to lock journal device: ") + strerror(errno));
         }
@@ -425,12 +447,15 @@ void blockstore_disk_t::open_journal()
 
 void blockstore_disk_t::close_all()
 {
-    if (data_fd >= 0)
-        close(data_fd);
-    if (meta_fd >= 0 && meta_fd != data_fd)
-        close(meta_fd);
-    if (journal_fd >= 0 && journal_fd != meta_fd)
-        close(journal_fd);
+    if (!mock_mode)
+    {
+        if (data_fd >= 0)
+            close(data_fd);
+        if (meta_fd >= 0 && meta_fd != data_fd)
+            close(meta_fd);
+        if (journal_fd >= 0 && journal_fd != meta_fd)
+            close(journal_fd);
+    }
     data_fd = meta_fd = journal_fd = -1;
 }
 
@@ -438,6 +463,10 @@ void blockstore_disk_t::close_all()
 // so it's not a big deal that we can only run it synchronously.
 int blockstore_disk_t::trim_data(std::function<bool(uint64_t)> is_free)
 {
+    if (mock_mode)
+    {
+        return -EINVAL;
+    }
     int r = 0;
     uint64_t j = 0, i = 0;
     uint64_t discarded = 0;
diff --git a/src/blockstore/blockstore_disk.h b/src/blockstore/blockstore_disk.h
index 7bd89bb1..55de03cd 100644
--- a/src/blockstore/blockstore_disk.h
+++ b/src/blockstore/blockstore_disk.h
@@ -17,6 +17,10 @@
 // Lower byte of checksum type is its length
 #define BLOCKSTORE_CSUM_CRC32C 0x104
 
+#define MOCK_DATA_FD 1000
+#define MOCK_META_FD 1001
+#define MOCK_JOURNAL_FD 1002
+
 class allocator_t;
 
 struct blockstore_disk_t
@@ -66,6 +70,8 @@ struct blockstore_disk_t
     uint32_t clean_entry_bitmap_size = 0;
     uint32_t clean_entry_size = 0, clean_dyn_size = 0; // for meta_v1/2
 
+    bool mock_mode = false;
+
     void parse_config(std::map<std::string, std::string> & config);
     void open_data();
     void open_meta();
diff --git a/src/blockstore/blockstore_impl.cpp b/src/blockstore/blockstore_impl.cpp
index 22583ec1..229753ca 100644
--- a/src/blockstore/blockstore_impl.cpp
+++ b/src/blockstore/blockstore_impl.cpp
@@ -5,11 +5,12 @@
 #include "blockstore_internal.h"
 #include "crc32c.h"
 
-blockstore_impl_t::blockstore_impl_t(blockstore_config_t & config, ring_loop_t *ringloop, timerfd_manager_t *tfd)
+blockstore_impl_t::blockstore_impl_t(blockstore_config_t & config, ring_loop_i *ringloop, timerfd_manager_t *tfd, bool mock_mode)
 {
     assert(sizeof(blockstore_op_private_t) <= BS_OP_PRIVATE_DATA_SIZE);
     this->tfd = tfd;
     this->ringloop = ringloop;
+    dsk.mock_mode = mock_mode;
     ring_consumer.loop = [this]() { loop(); };
     ringloop->register_consumer(&ring_consumer);
     initialized = 0;
diff --git a/src/blockstore/blockstore_impl.h b/src/blockstore/blockstore_impl.h
index 2462962e..4cf71a83 100644
--- a/src/blockstore/blockstore_impl.h
+++ b/src/blockstore/blockstore_impl.h
@@ -124,7 +124,7 @@ class blockstore_impl_t: public blockstore_i
     bool fsyncing_data = false;
 
     bool live = false, queue_stall = false;
-    ring_loop_t *ringloop;
+    ring_loop_i *ringloop;
     timerfd_manager_t *tfd;
 
     bool stop_sync_submitted;
@@ -187,7 +187,7 @@ class blockstore_impl_t: public blockstore_i
 
 public:
 
-    blockstore_impl_t(blockstore_config_t & config, ring_loop_t *ringloop, timerfd_manager_t *tfd);
+    blockstore_impl_t(blockstore_config_t & config, ring_loop_i *ringloop, timerfd_manager_t *tfd, bool mock_mode = false);
     ~blockstore_impl_t();
 
     void parse_config(blockstore_config_t & config);
diff --git a/src/util/ringloop.cpp b/src/util/ringloop.cpp
index 10af62f4..862ec715 100644
--- a/src/util/ringloop.cpp
+++ b/src/util/ringloop.cpp
@@ -8,6 +8,7 @@
 
 #include <sys/eventfd.h>
 
+#include "malloc_or_die.h"
 #include "ringloop.h"
 
 ring_loop_t::ring_loop_t(int qd, bool multithreaded, bool sqe128)
@@ -228,3 +229,230 @@ int ring_loop_t::register_eventfd()
     loop();
     return ring_eventfd;
 }
+
+ring_loop_mock_t::ring_loop_mock_t(int qd, std::function<void(io_uring_sqe *)> submit_cb)
+{
+    this->submit_cb = std::move(submit_cb);
+    sqes.resize(qd);
+    ring_datas.resize(qd);
+    free_ring_datas.reserve(qd);
+    submit_ring_datas.reserve(qd);
+    completed_ring_datas.reserve(qd);
+    for (size_t i = 0; i < ring_datas.size(); i++)
+    {
+        free_ring_datas.push_back(ring_datas.data() + i);
+    }
+    in_loop = false;
+}
+
+void ring_loop_mock_t::register_consumer(ring_consumer_t *consumer)
+{
+    unregister_consumer(consumer);
+    consumers.push_back(consumer);
+}
+
+void ring_loop_mock_t::unregister_consumer(ring_consumer_t *consumer)
+{
+    for (int i = 0; i < consumers.size(); i++)
+    {
+        if (consumers[i] == consumer)
+        {
+            consumers.erase(consumers.begin()+i, consumers.begin()+i+1);
+            break;
+        }
+    }
+}
+
+void ring_loop_mock_t::wakeup()
+{
+    loop_again = true;
+}
+
+void ring_loop_mock_t::set_immediate(const std::function<void()> & cb)
+{
+    immediate_queue.push_back(cb);
+    wakeup();
+}
+
+unsigned ring_loop_mock_t::space_left()
+{
+    return free_ring_datas.size();
+}
+
+bool ring_loop_mock_t::has_work()
+{
+    return loop_again;
+}
+
+bool ring_loop_mock_t::has_sendmsg_zc()
+{
+    return false;
+}
+
+int ring_loop_mock_t::register_eventfd()
+{
+    return -1;
+}
+
+io_uring_sqe* ring_loop_mock_t::get_sqe()
+{
+    if (free_ring_datas.size() == 0)
+    {
+        return NULL;
+    }
+    ring_data_t *d = free_ring_datas.back();
+    free_ring_datas.pop_back();
+    submit_ring_datas.push_back(d);
+    io_uring_sqe *sqe = &sqes[d - ring_datas.data()];
+    *sqe = { 0 };
+    io_uring_sqe_set_data(sqe, d);
+    return sqe;
+}
+
+int ring_loop_mock_t::submit()
+{
+    for (size_t i = 0; i < submit_ring_datas.size(); i++)
+    {
+        submit_cb(&sqes[submit_ring_datas[i] - ring_datas.data()]);
+    }
+    submit_ring_datas.clear();
+    return 0;
+}
+
+int ring_loop_mock_t::wait()
+{
+    return 0;
+}
+
+unsigned ring_loop_mock_t::save()
+{
+    return submit_ring_datas.size();
+}
+
+void ring_loop_mock_t::restore(unsigned sqe_tail)
+{
+    while (submit_ring_datas.size() > sqe_tail)
+    {
+        free_ring_datas.push_back(submit_ring_datas.back());
+        submit_ring_datas.pop_back();
+    }
+}
+
+void ring_loop_mock_t::loop()
+{
+    if (in_loop)
+    {
+        return;
+    }
+    in_loop = true;
+    submit();
+    while (completed_ring_datas.size())
+    {
+        ring_data_t *d = completed_ring_datas.back();
+        completed_ring_datas.pop_back();
+        if (d->callback)
+        {
+            struct ring_data_t dl;
+            dl.iov = d->iov;
+            dl.res = d->res;
+            dl.more = dl.prev = false;
+            dl.callback.swap(d->callback);
+            free_ring_datas.push_back(d);
+            dl.callback(&dl);
+        }
+        else
+        {
+            fprintf(stderr, "Warning: empty callback in SQE\n");
+            free_ring_datas.push_back(d);
+        }
+    }
+    do
+    {
+        loop_again = false;
+        for (int i = 0; i < consumers.size(); i++)
+        {
+            consumers[i]->loop();
+            if (immediate_queue.size())
+            {
+                immediate_queue2.swap(immediate_queue);
+                for (auto & cb: immediate_queue2)
+                    cb();
+                immediate_queue2.clear();
+            }
+        }
+    } while (loop_again);
+    in_loop = false;
+}
+
+void ring_loop_mock_t::mark_completed(ring_data_t *data)
+{
+    completed_ring_datas.push_back(data);
+    wakeup();
+}
+
+disk_mock_t::disk_mock_t(ring_loop_mock_t *loop, size_t size)
+{
+    this->loop = loop;
+    this->size = size;
+    this->data = (uint8_t*)malloc_or_die(size);
+}
+
+disk_mock_t::~disk_mock_t()
+{
+    free(data);
+}
+
+bool disk_mock_t::submit(io_uring_sqe *sqe)
+{
+    ring_data_t *userdata = (ring_data_t*)sqe->user_data;
+    if (sqe->opcode == IORING_OP_READV)
+    {
+        size_t off = sqe->off;
+        iovec *v = (iovec*)sqe->addr;
+        size_t n = sqe->len;
+        for (size_t i = 0; i < n; i++)
+        {
+            size_t cur = (off + v[i].iov_len > size ? size-off : v[i].iov_len);
+            if (trace)
+                printf("read %zu+%zu to %jx\n", off, cur, (uint64_t)v[i].iov_base);
+            memcpy(v[i].iov_base, data + off, cur);
+            off += v[i].iov_len;
+        }
+        userdata->res = off - sqe->off;
+    }
+    else if (sqe->opcode == IORING_OP_WRITEV)
+    {
+        // Simple "immediate" mode. We should also implement "buffered" mode
+        size_t off = sqe->off;
+        iovec *v = (iovec*)sqe->addr;
+        size_t n = sqe->len;
+        for (size_t i = 0; i < n; i++)
+        {
+            if (off >= size)
+            {
+                off = sqe->off - EINVAL; // :D
+                break;
+            }
+            size_t cur = (off + v[i].iov_len > size ? size-off : v[i].iov_len);
+            if (trace)
+                printf("write %zu+%zu from %jx\n", off, cur, (uint64_t)v[i].iov_base);
+            memcpy(data + off, v[i].iov_base, cur);
+            off += v[i].iov_len;
+        }
+        userdata->res = off - sqe->off;
+    }
+    else if (sqe->opcode == IORING_OP_FSYNC)
+    {
+        userdata->res = 0;
+    }
+    else
+    {
+        return false;
+    }
+    // Execution variability should also be introduced:
+    // 1) reads submitted in parallel to writes (not after completing the write) should return old or new data randomly
+    // 2) parallel operation completions should be delivered in random order
+    // 3) when fsync is enabled, write cache should be sometimes lost during a simulated power outage
+    loop->mark_completed(userdata);
+    return true;
+}
diff --git a/src/util/ringloop.h b/src/util/ringloop.h
index c397461f..5996ded5 100644
--- a/src/util/ringloop.h
+++ b/src/util/ringloop.h
@@ -32,7 +32,27 @@ struct ring_consumer_t
     std::function<void(void)> loop;
 };
 
-class __attribute__((visibility("default"))) ring_loop_t
+class __attribute__((visibility("default"))) ring_loop_i
+{
+public:
+    virtual ~ring_loop_i() = default;
+    virtual void register_consumer(ring_consumer_t *consumer) = 0;
+    virtual void unregister_consumer(ring_consumer_t *consumer) = 0;
+    virtual int register_eventfd() = 0;
+    virtual io_uring_sqe* get_sqe() = 0;
+    virtual void set_immediate(const std::function<void()> & cb) = 0;
+    virtual int submit() = 0;
+    virtual int wait() = 0;
+    virtual unsigned space_left() = 0;
+    virtual bool has_work() = 0;
+    virtual bool has_sendmsg_zc() = 0;
+    virtual void loop() = 0;
+    virtual void wakeup() = 0;
+    virtual unsigned save() = 0;
+    virtual void restore(unsigned sqe_tail) = 0;
+};
+
+class __attribute__((visibility("default"))) ring_loop_t: public ring_loop_i
 {
     std::vector<std::function<void()>> immediate_queue, immediate_queue2;
     std::vector<ring_consumer_t*> consumers;
@@ -54,7 +74,7 @@ public:
     int register_eventfd();
 
     io_uring_sqe* get_sqe();
-    inline void set_immediate(const std::function<void()> cb)
+    inline void set_immediate(const std::function<void()> & cb)
     {
         immediate_queue.push_back(cb);
         wakeup();
@@ -84,3 +104,51 @@ public:
     unsigned save();
     void restore(unsigned sqe_tail);
 };
+
+class ring_loop_mock_t: public ring_loop_i
+{
+    std::vector<std::function<void()>> immediate_queue, immediate_queue2;
+    std::vector<ring_consumer_t*> consumers;
+    std::vector<io_uring_sqe> sqes;
+    std::vector<ring_data_t> ring_datas;
+    std::vector<ring_data_t *> free_ring_datas;
+    std::vector<ring_data_t *> submit_ring_datas;
+    std::vector<ring_data_t *> completed_ring_datas;
+    std::function<void(io_uring_sqe *)> submit_cb;
+    bool in_loop;
+    bool loop_again;
+    bool support_zc = false;
+
+public:
+    ring_loop_mock_t(int qd, std::function<void(io_uring_sqe *)> submit_cb);
+
+    void register_consumer(ring_consumer_t *consumer);
+    void unregister_consumer(ring_consumer_t *consumer);
+    void wakeup();
+    void set_immediate(const std::function<void()> & cb);
+    unsigned space_left();
+    bool has_work();
+    bool has_sendmsg_zc();
+
+    int register_eventfd();
+    io_uring_sqe* get_sqe();
+    int submit();
+    int wait();
+    void loop();
+    unsigned save();
+    void restore(unsigned sqe_tail);
+
+    void mark_completed(ring_data_t *data);
+};
+
+class disk_mock_t
+{
+    uint8_t *data = NULL;
+    size_t size = 0;
+    ring_loop_mock_t *loop = NULL;
+public:
+    bool trace = false;
+    disk_mock_t(ring_loop_mock_t *loop, size_t size);
+    ~disk_mock_t();
+    bool submit(io_uring_sqe *sqe);
+};
diff --git a/src/util/timerfd_manager.cpp b/src/util/timerfd_manager.cpp
index cafb10c3..e64ebc88 100644
--- a/src/util/timerfd_manager.cpp
+++ b/src/util/timerfd_manager.cpp
@@ -4,6 +4,7 @@
 #include <sys/timerfd.h>
 #include <sys/poll.h>
 #include <sys/epoll.h>
+#include <assert.h>
 #include <unistd.h>
 #include <errno.h>
 #include <string.h>
@@ -15,21 +16,27 @@ timerfd_manager_t::timerfd_manager_t(std::function<void(int, bool, std::function
 {
     this->set_fd_handler = set_fd_handler;
     wait_state = 0;
-    timerfd = timerfd_create(CLOCK_MONOTONIC, TFD_NONBLOCK);
-    if (timerfd < 0)
+    if (set_fd_handler)
     {
-        throw std::runtime_error(std::string("timerfd_create: ") + strerror(errno));
+        timerfd = timerfd_create(CLOCK_MONOTONIC, TFD_NONBLOCK);
+        if (timerfd < 0)
+        {
+            throw std::runtime_error(std::string("timerfd_create: ") + strerror(errno));
+        }
+        set_fd_handler(timerfd, false, [this](int fd, int events)
+        {
+            handle_readable();
+        });
     }
-    set_fd_handler(timerfd, false, [this](int fd, int events)
-    {
-        handle_readable();
-    });
 }
 
 timerfd_manager_t::~timerfd_manager_t()
 {
-    set_fd_handler(timerfd, false, NULL);
-    close(timerfd);
+    if (timerfd >= 0)
+    {
+        set_fd_handler(timerfd, false, NULL);
+        close(timerfd);
+    }
 }
 
 void timerfd_manager_t::inc_timer(timerfd_timer_t & t)
@@ -52,7 +59,14 @@ int timerfd_manager_t::set_timer_us(uint64_t micros, bool repeat, std::function<
 {
     int timer_id = id++;
     timespec start;
-    clock_gettime(CLOCK_MONOTONIC, &start);
+    if (timerfd >= 0)
+    {
+        clock_gettime(CLOCK_MONOTONIC, &start);
+    }
+    else
+    {
+        start = cur;
+    }
     timers.push_back({
         .id = timer_id,
         .micros = micros,
@@ -101,7 +115,7 @@ again:
     {
         nearest = -1;
         itimerspec exp = {};
-        if (timerfd_settime(timerfd, 0, &exp, NULL))
+        if (timerfd >= 0 && timerfd_settime(timerfd, 0, &exp, NULL))
         {
             throw std::runtime_error(std::string("timerfd_settime: ") + strerror(errno));
         }
@@ -120,7 +134,14 @@ again:
             }
         }
         timespec now;
-        clock_gettime(CLOCK_MONOTONIC, &now);
+        if (timerfd >= 0)
+        {
+            clock_gettime(CLOCK_MONOTONIC, &now);
+        }
+        else
+        {
+            now = cur;
+        }
         itimerspec exp = {
             .it_interval = { 0 },
             .it_value = timers[nearest].next,
@@ -142,7 +163,7 @@ again:
             }
             exp.it_value = { .tv_sec = 0, .tv_nsec = 1 };
         }
-        if (timerfd_settime(timerfd, 0, &exp, NULL))
+        if (timerfd >= 0 && timerfd_settime(timerfd, 0, &exp, NULL))
         {
             throw std::runtime_error(std::string("timerfd_settime: ") + strerror(errno));
         }
@@ -178,3 +199,13 @@ void timerfd_manager_t::trigger_nearest()
     nearest = -1;
     cb(nearest_id);
 }
+
+void timerfd_manager_t::tick(timespec passed)
+{
+    assert(timerfd == -1);
+    cur.tv_sec += passed.tv_sec;
+    cur.tv_nsec += passed.tv_nsec;
+    cur.tv_sec += (cur.tv_nsec / 1000000000);
+    cur.tv_nsec = (cur.tv_nsec % 1000000000);
+    set_nearest(true);
+}
diff --git a/src/util/timerfd_manager.h b/src/util/timerfd_manager.h
index 58c58465..e127bd08 100644
--- a/src/util/timerfd_manager.h
+++ b/src/util/timerfd_manager.h
@@ -19,11 +19,12 @@ struct timerfd_timer_t
 class __attribute__((visibility("default"))) timerfd_manager_t
 {
     int wait_state = 0;
-    int timerfd;
+    int timerfd = -1;
     int nearest = -1;
     int id = 1;
     int onstack = 0;
     std::vector<timerfd_timer_t> timers;
+    timespec cur = {};
 
     void inc_timer(timerfd_timer_t & t);
     void set_nearest(bool trigger_inline);
@@ -37,4 +38,5 @@ public:
     int set_timer(uint64_t millis, bool repeat, std::function<void(int)> callback);
     int set_timer_us(uint64_t micros, bool repeat, std::function<void(int)> callback);
     void clear_timer(int timer_id);
+    void tick(timespec passed);
 };