diff --git a/lci/api/lci.h b/lci/api/lci.h
index ab2d6bdc..383914bd 100644
--- a/lci/api/lci.h
+++ b/lci/api/lci.h
@@ -644,6 +644,18 @@ typedef enum {
 } LCI_backend_try_lock_mode_t;
 extern uint64_t LCI_BACKEND_TRY_LOCK_MODE;
 
+/**
+ * @ingroup LCI_COMM
+ * @brief Try_lock mode of LCI runtime.
+ */
+typedef enum {
+  LCI_DEVICE_LOCK_MODE_NONE,
+  LCI_DEVICE_LOCK_MODE_BLOCK,
+  LCI_DEVICE_LOCK_MODE_TRY,
+  LCI_DEVICE_LOCK_MODE_MAX,
+} LCI_DEVICE_LOCK_MODE_t;
+extern uint64_t LCI_DEVICE_LOCK_MODE;
+
 /**
  * @ingroup LCI_DEVICE
  * @brief Default device initialized by LCI_initialize. Just for convenience.
diff --git a/lci/runtime/1sided_primitive.c b/lci/runtime/1sided_primitive.c
index 49db3933..2c87bab5 100644
--- a/lci/runtime/1sided_primitive.c
+++ b/lci/runtime/1sided_primitive.c
@@ -10,9 +10,11 @@ LCI_error_t LCI_puts(LCI_endpoint_t ep, LCI_short_t src, int rank,
                  "Only support default remote completion "
                  "(set by LCI_plist_set_default_comp, "
                  "the default value is LCI_UR_CQ)\n");
+  LCII_DEVICE_CS_ENTER(ep->device);
   LCI_error_t ret = LCIS_post_sends(
       ep->device->endpoint_worker->endpoint, rank, &src, sizeof(LCI_short_t),
       LCII_MAKE_PROTO(ep->gid, LCI_MSG_RDMA_SHORT, tag));
+  LCII_DEVICE_CS_EXIT(ep->device);
   if (ret == LCI_OK) {
     LCII_PCOUNTER_ADD(put, sizeof(LCI_short_t));
   }
@@ -48,6 +50,7 @@ LCI_error_t LCI_putmac(LCI_endpoint_t ep, LCI_mbuffer_t buffer, int rank,
                  "Only support default remote completion "
                  "(set by LCI_plist_set_default_comp, "
                  "the default value is LCI_UR_CQ)\n");
+  LCII_DEVICE_CS_ENTER(ep->device);
   LCI_error_t ret = LCI_OK;
   bool is_user_provided_packet =
       LCII_is_packet(ep->device->heap, buffer.address);
@@ -70,6 +73,7 @@ LCI_error_t LCI_putmac(LCI_endpoint_t ep, LCI_mbuffer_t buffer, int rank,
       packet = LCII_alloc_packet_nb(ep->pkpool);
       if (packet == NULL) {
         // no packet is available
+        LCII_DEVICE_CS_EXIT(ep->device);
         return LCI_ERR_RETRY;
       }
       memcpy(packet->data.address, buffer.address, buffer.length);
@@ -102,6 +106,7 @@ LCI_error_t LCI_putmac(LCI_endpoint_t ep, LCI_mbuffer_t buffer, int rank,
       LCIU_free(ctx);
     }
   }
+  LCII_DEVICE_CS_EXIT(ep->device);
   if (ret == LCI_OK) {
     LCII_PCOUNTER_ADD(put, (int64_t)buffer.length);
   }
@@ -143,12 +148,15 @@ LCI_error_t LCI_putla(LCI_endpoint_t ep, LCI_lbuffer_t buffer,
                  "Only support default remote completion "
                  "(set by LCI_plist_set_default_comp, "
                  "the default value is LCI_UR_CQ)\n");
+  LCII_DEVICE_CS_ENTER(ep->device);
   if (!LCII_bq_is_empty(ep->bq_p)) {
+    LCII_DEVICE_CS_EXIT(ep->device);
     return LCI_ERR_RETRY;
   }
   LCII_packet_t* packet = LCII_alloc_packet_nb(ep->pkpool);
   if (packet == NULL) {
     // no packet is available
+    LCII_DEVICE_CS_EXIT(ep->device);
     return LCI_ERR_RETRY;
   }
   packet->context.poolid = LCII_POOLID_LOCAL;
@@ -187,6 +195,7 @@ LCI_error_t LCI_putla(LCI_endpoint_t ep, LCI_lbuffer_t buffer,
     LCIU_free(rts_ctx);
     LCIU_free(rdv_ctx);
   }
+  LCII_DEVICE_CS_EXIT(ep->device);
   if (ret == LCI_OK) {
     LCII_PCOUNTER_ADD(put, (int64_t)buffer.length);
   }
@@ -217,6 +226,7 @@ LCI_error_t LCI_putva(LCI_endpoint_t ep, LCI_iovec_t iovec,
       iovec.piggy_back.length <= LCI_get_iovec_piggy_back_size(iovec.count),
       "iovec's piggy back is too large! (%lu > %lu)\n", iovec.piggy_back.length,
       LCI_get_iovec_piggy_back_size(iovec.count));
+  LCII_DEVICE_CS_ENTER(ep->device);
   for (int i = 0; i < iovec.count; ++i) {
     LCI_DBG_Assert(
         (iovec.lbuffers[0].segment == LCI_SEGMENT_ALL &&
@@ -228,11 +238,13 @@ LCI_error_t LCI_putva(LCI_endpoint_t ep, LCI_iovec_t iovec,
     LCI_DBG_Assert(iovec.lbuffers[i].length > 0, "Invalid lbuffer length\n");
   }
   if (!LCII_bq_is_empty(ep->bq_p)) {
+    LCII_DEVICE_CS_EXIT(ep->device);
     return LCI_ERR_RETRY;
   }
   LCII_packet_t* packet = LCII_alloc_packet_nb(ep->pkpool);
   if (packet == NULL) {
     // no packet is available
+    LCII_DEVICE_CS_EXIT(ep->device);
     return LCI_ERR_RETRY;
   }
   packet->context.poolid =
@@ -286,6 +298,7 @@ LCI_error_t LCI_putva(LCI_endpoint_t ep, LCI_iovec_t iovec,
     LCIU_free(rts_ctx);
     LCIU_free(rdv_ctx);
   }
+  LCII_DEVICE_CS_EXIT(ep->device);
   if (ret == LCI_OK) {
     uint64_t total_length = iovec.piggy_back.length;
     for (int i = 0; i < iovec.count; ++i) {
diff --git a/lci/runtime/2sided_primitive.c b/lci/runtime/2sided_primitive.c
index 4b063854..2fb42905 100644
--- a/lci/runtime/2sided_primitive.c
+++ b/lci/runtime/2sided_primitive.c
@@ -6,9 +6,11 @@ LCI_error_t LCI_sends(LCI_endpoint_t ep, LCI_short_t src, int rank,
 {
   LCI_DBG_Assert(tag <= LCI_MAX_TAG, "tag %d is too large (maximum: %d)\n", tag,
                  LCI_MAX_TAG);
+  LCII_DEVICE_CS_ENTER(ep->device);
   LCI_error_t ret = LCIS_post_sends(
       ep->device->endpoint_worker->endpoint, rank, &src, sizeof(LCI_short_t),
       LCII_MAKE_PROTO(ep->gid, LCI_MSG_SHORT, tag));
+  LCII_DEVICE_CS_EXIT(ep->device);
   if (ret == LCI_OK) {
     LCII_PCOUNTER_ADD(send, sizeof(LCI_short_t));
   }
@@ -25,6 +27,7 @@ LCI_error_t LCI_sendmc(LCI_endpoint_t ep, LCI_mbuffer_t buffer, int rank,
   LCI_DBG_Assert(buffer.length <= LCI_MEDIUM_SIZE,
                  "buffer is too large %lu (maximum: %d)\n", buffer.length,
                  LCI_MEDIUM_SIZE);
+  LCII_DEVICE_CS_ENTER(ep->device);
   LCI_error_t ret = LCI_OK;
   bool is_user_provided_packet =
       LCII_is_packet(ep->device->heap, buffer.address);
@@ -47,6 +50,7 @@ LCI_error_t LCI_sendmc(LCI_endpoint_t ep, LCI_mbuffer_t buffer, int rank,
       packet = LCII_alloc_packet_nb(ep->pkpool);
       if (packet == NULL) {
         // no packet is available
+        LCII_DEVICE_CS_EXIT(ep->device);
         return LCI_ERR_RETRY;
       }
       memcpy(packet->data.address, buffer.address, buffer.length);
@@ -80,6 +84,7 @@ LCI_error_t LCI_sendmc(LCI_endpoint_t ep, LCI_mbuffer_t buffer, int rank,
       LCIU_free(ctx);
     }
   }
+  LCII_DEVICE_CS_EXIT(ep->device);
   if (ret == LCI_OK) {
     LCII_PCOUNTER_ADD(send, (int64_t)buffer.length);
   }
@@ -108,12 +113,15 @@ LCI_error_t LCI_sendl(LCI_endpoint_t ep, LCI_lbuffer_t buffer, int rank,
 {
   LCI_DBG_Assert(tag <= LCI_MAX_TAG, "tag %d is too large (maximum: %d)\n", tag,
                  LCI_MAX_TAG);
+  LCII_DEVICE_CS_ENTER(ep->device);
   if (!LCII_bq_is_empty(ep->bq_p)) {
+    LCII_DEVICE_CS_EXIT(ep->device);
     return LCI_ERR_RETRY;
   }
   LCII_packet_t* packet = LCII_alloc_packet_nb(ep->pkpool);
   if (packet == NULL) {
     // no packet is available
+    LCII_DEVICE_CS_EXIT(ep->device);
     return LCI_ERR_RETRY;
   }
   packet->context.poolid = LCII_POOLID_LOCAL;
@@ -149,6 +157,7 @@ LCI_error_t LCI_sendl(LCI_endpoint_t ep, LCI_lbuffer_t buffer, int rank,
     LCIU_free(rts_ctx);
     LCIU_free(rdv_ctx);
   }
+  LCII_DEVICE_CS_EXIT(ep->device);
   if (ret == LCI_OK) {
     LCII_PCOUNTER_ADD(send, (int64_t)buffer.length);
   }
@@ -165,6 +174,7 @@ LCI_error_t LCI_recvs(LCI_endpoint_t ep, int rank, LCI_tag_t tag,
 {
   LCI_DBG_Assert(tag <= LCI_MAX_TAG, "tag %d is too large (maximum: %d)\n", tag,
                  LCI_MAX_TAG);
+  LCII_DEVICE_CS_ENTER(ep->device);
   LCII_context_t* ctx = LCIU_malloc(sizeof(LCII_context_t));
   ctx->data_type = LCI_IMMEDIATE;
   ctx->rank = rank;
@@ -184,6 +194,7 @@ LCI_error_t LCI_recvs(LCI_endpoint_t ep, int rank, LCI_tag_t tag,
     LCII_free_packet(packet);
     lc_ce_dispatch(ctx);
   }
+  LCII_DEVICE_CS_EXIT(ep->device);
   LCII_PCOUNTER_ADD(recv, 1);
   LCI_DBG_Log(LCI_LOG_TRACE, "comm",
               "LCI_recvs(ep %p, rank %d, tag %u, completion %p, user_context "
@@ -200,6 +211,7 @@ LCI_error_t LCI_recvm(LCI_endpoint_t ep, LCI_mbuffer_t buffer, int rank,
   LCI_DBG_Assert(buffer.length <= LCI_MEDIUM_SIZE,
                  "buffer is too large %lu (maximum: %d)\n", buffer.length,
                  LCI_MEDIUM_SIZE);
+  LCII_DEVICE_CS_ENTER(ep->device);
   LCII_context_t* ctx = LCIU_malloc(sizeof(LCII_context_t));
   ctx->data.mbuffer = buffer;
   ctx->data_type = LCI_MEDIUM;
@@ -223,6 +235,7 @@ LCI_error_t LCI_recvm(LCI_endpoint_t ep, LCI_mbuffer_t buffer, int rank,
     LCII_free_packet(packet);
     lc_ce_dispatch(ctx);
   }
+  LCII_DEVICE_CS_EXIT(ep->device);
   LCII_PCOUNTER_ADD(recv, 1);
   LCI_DBG_Log(LCI_LOG_TRACE, "comm",
               "LCI_recvm(ep %p, buffer {%p, %lu}, rank %d, tag %u, completion "
@@ -237,6 +250,7 @@ LCI_error_t LCI_recvmn(LCI_endpoint_t ep, int rank, LCI_tag_t tag,
 {
   LCI_DBG_Assert(tag <= LCI_MAX_TAG, "tag %d is too large (maximum: %d)\n", tag,
                  LCI_MAX_TAG);
+  LCII_DEVICE_CS_ENTER(ep->device);
   LCII_context_t* ctx = LCIU_malloc(sizeof(LCII_context_t));
   ctx->data.mbuffer.address = NULL;
   ctx->data_type = LCI_MEDIUM;
@@ -258,6 +272,7 @@ LCI_error_t LCI_recvmn(LCI_endpoint_t ep, int rank, LCI_tag_t tag,
     ctx->data.mbuffer.address = packet->data.address;
     lc_ce_dispatch(ctx);
   }
+  LCII_DEVICE_CS_EXIT(ep->device);
   LCII_PCOUNTER_ADD(recv, 1);
   LCI_DBG_Log(LCI_LOG_TRACE, "comm",
               "LCI_recvmn(ep %p, rank %d, tag %u, completion %p, user_context "
@@ -271,6 +286,7 @@ LCI_error_t LCI_recvl(LCI_endpoint_t ep, LCI_lbuffer_t buffer, int rank,
 {
   LCI_DBG_Assert(tag <= LCI_MAX_TAG, "tag %d is too large (maximum: %d)\n", tag,
                  LCI_MAX_TAG);
+  LCII_DEVICE_CS_ENTER(ep->device);
   LCII_context_t* rdv_ctx = LCIU_malloc(sizeof(LCII_context_t));
   rdv_ctx->data.lbuffer = buffer;
   rdv_ctx->data_type = LCI_LONG;
@@ -292,6 +308,7 @@ LCI_error_t LCI_recvl(LCI_endpoint_t ep, LCI_lbuffer_t buffer, int rank,
     LCII_packet_t* packet = (LCII_packet_t*)value;
     LCII_handle_rts(ep, packet, packet->context.src_rank, tag, rdv_ctx, false);
   }
+  LCII_DEVICE_CS_EXIT(ep->device);
   LCII_PCOUNTER_ADD(recv, 1);
   LCI_DBG_Log(LCI_LOG_TRACE, "comm",
               "LCI_recvl(ep %p, buffer {%p, %lu, %p}, rank %d, tag %u, "
diff --git a/lci/runtime/device.c b/lci/runtime/device.c
index 96c2d06a..2a016289 100644
--- a/lci/runtime/device.c
+++ b/lci/runtime/device.c
@@ -59,6 +59,7 @@ LCI_error_t LCI_device_init(LCI_device_t* device_ptr)
   LCM_archive_init(&(device->ctx_archive), 16);
   LCII_bq_init(&device->bq);
   LCIU_spinlock_init(&device->bq_spinlock);
+  LCIU_spinlock_init(&device->device_lock);
 
   if (LCI_USE_GLOBAL_PACKET_POOL) {
     device->heap = &g_heap;
@@ -101,6 +102,7 @@ LCI_error_t LCI_device_free(LCI_device_t* device_ptr)
   LCII_matchtable_free(&device->mt);
   LCM_archive_fini(&(device->ctx_archive));
   LCII_bq_fini(&device->bq);
+  LCIU_spinlock_fina(&device->device_lock);
   LCIU_spinlock_fina(&device->bq_spinlock);
   if (LCI_USE_DREG) {
     LCII_rcache_fina(device);
diff --git a/lci/runtime/env.c b/lci/runtime/env.c
index f0470868..673af1df 100644
--- a/lci/runtime/env.c
+++ b/lci/runtime/env.c
@@ -32,6 +32,7 @@ LCI_API bool LCI_ENABLE_PRG_NET_ENDPOINT;
 LCI_API LCI_rdv_protocol_t LCI_RDV_PROTOCOL;
 LCI_API bool LCI_OFI_CXI_TRY_NO_HACK;
 LCI_API uint64_t LCI_BACKEND_TRY_LOCK_MODE;
+LCI_API uint64_t LCI_DEVICE_LOCK_MODE;
 LCI_API bool LCI_UCX_USE_TRY_LOCK;
 LCI_API bool LCI_UCX_PROGRESS_FOCUSED;
 LCI_API bool LCI_USE_GLOBAL_PACKET_POOL;
@@ -128,6 +129,25 @@ void LCII_env_init(int num_proc, int rank)
     LCI_Log(LCI_LOG_INFO, "env", "set LCI_BACKEND_TRY_LOCK_MODE to be %d\n",
             LCI_BACKEND_TRY_LOCK_MODE);
   }
+  {
+    // default value
+    LCI_DEVICE_LOCK_MODE = 0;
+    // if users explicitly set the value
+    char* p = getenv("LCI_DEVICE_LOCK_MODE");
+    if (p) {
+      LCT_dict_str_int_t dict[] = {
+          {"none", LCI_DEVICE_LOCK_MODE_NONE},
+          {"try", LCI_DEVICE_LOCK_MODE_TRY},
+          {"block", LCI_DEVICE_LOCK_MODE_BLOCK},
+      };
+      LCI_DEVICE_LOCK_MODE =
+          LCT_parse_arg(dict, sizeof(dict) / sizeof(dict[0]), p, ",");
+    }
+    LCI_Assert(LCI_DEVICE_LOCK_MODE < LCI_DEVICE_LOCK_MODE_MAX,
+               "Unexpected LCI_DEVICE_LOCK_MODE %d", LCI_DEVICE_LOCK_MODE);
+    LCI_Log(LCI_LOG_INFO, "env", "set LCI_DEVICE_LOCK_MODE to be %d\n",
+            LCI_DEVICE_LOCK_MODE);
+  }
   LCI_UCX_USE_TRY_LOCK = LCIU_getenv_or("LCI_UCX_USE_TRY_LOCK", 0);
   LCI_UCX_PROGRESS_FOCUSED = LCIU_getenv_or("LCI_UCX_PROGRESS_FOCUSED", 0);
   LCI_USE_GLOBAL_PACKET_POOL = LCIU_getenv_or("LCI_USE_GLOBAL_PACKET_POOL", 1);
diff --git a/lci/runtime/lcii.h b/lci/runtime/lcii.h
index 1302c2a0..d0f3d144 100644
--- a/lci/runtime/lcii.h
+++ b/lci/runtime/lcii.h
@@ -17,6 +17,7 @@
 #include "backlog_queue.h"
 
 extern uint64_t LCI_PAGESIZE;
+
 /*
  * used by
  * - LCII_MAKE_PROTO (4 bits) for communication immediate data field
@@ -89,8 +90,27 @@ struct __attribute__((aligned(LCI_CACHE_LINE))) LCI_device_s {
   LCII_backlog_queue_t bq;
   LCIU_spinlock_t bq_spinlock;
   LCIU_CACHE_PADDING((sizeof(LCII_backlog_queue_t) + sizeof(LCIU_spinlock_t)));
+  LCIU_spinlock_t device_lock;  // used for device lock
+  LCIU_CACHE_PADDING((sizeof(LCIU_spinlock_t)));
 };
 
+// device lock mode
+#define LCII_DEVICE_CS_ENTER_PROGRESS(device_p, ret)           \
+  if (LCI_DEVICE_LOCK_MODE == LCI_DEVICE_LOCK_MODE_TRY &&      \
+      !LCIU_try_acquire_spinlock(&device_p->device_lock))      \
+    return ret;                                                \
+  else if (LCI_DEVICE_LOCK_MODE == LCI_DEVICE_LOCK_MODE_BLOCK) \
+    LCIU_acquire_spinlock(&device_p->device_lock);
+
+#define LCII_DEVICE_CS_ENTER(device_p)                    \
+  if (LCI_DEVICE_LOCK_MODE == LCI_DEVICE_LOCK_MODE_TRY || \
+      LCI_DEVICE_LOCK_MODE == LCI_DEVICE_LOCK_MODE_BLOCK) \
+    LCIU_acquire_spinlock(&device_p->device_lock);
+
+#define LCII_DEVICE_CS_EXIT(device_p)                    \
+  if (LCI_DEVICE_LOCK_MODE != LCI_DEVICE_LOCK_MODE_NONE) \
+    LCIU_release_spinlock(&device_p->device_lock);
+
 struct LCI_plist_s {
   LCI_match_t match_type;         // matching type
   LCI_comp_type_t cmd_comp_type;  // source-side completion type
diff --git a/lci/runtime/progress.c b/lci/runtime/progress.c
index 79b02b94..2f6581a5 100644
--- a/lci/runtime/progress.c
+++ b/lci/runtime/progress.c
@@ -154,6 +154,8 @@ LCI_error_t LCII_fill_rq(LCII_endpoint_t* endpoint, bool block)
 LCI_error_t LCI_progress(LCI_device_t device)
 {
   int ret = LCI_ERR_RETRY;
+  LCII_PCOUNTER_ADD(progress_call, 1);
+  LCII_DEVICE_CS_ENTER_PROGRESS(device, ret);
   // we want to make progress on the endpoint_progress as much as possible
   // to speed up rendezvous protocol
   while (LCI_ENABLE_PRG_NET_ENDPOINT &&
@@ -175,6 +177,6 @@ LCI_error_t LCI_progress(LCI_device_t device)
   if (LCII_fill_rq(device->endpoint_worker, false) == LCI_OK) {
     ret = LCI_OK;
   }
-  LCII_PCOUNTER_ADD(progress_call, 1);
+  LCII_DEVICE_CS_EXIT(device);
   return ret;
 }