diff --git a/darshan-runtime/lib/darshan-dxt.c b/darshan-runtime/lib/darshan-dxt.c
index 7412b4e4c..fd2407353 100644
--- a/darshan-runtime/lib/darshan-dxt.c
+++ b/darshan-runtime/lib/darshan-dxt.c
@@ -108,6 +108,7 @@ static struct dxt_file_record_ref *dxt_posix_track_new_file_record(
     darshan_record_id rec_id);
 static struct dxt_file_record_ref *dxt_mpiio_track_new_file_record(
     darshan_record_id rec_id);
+void annotate_trace_segment(char *extra_info_str);
 
 /* DXT output/cleanup routines for darshan-core */
 static void dxt_posix_output(
@@ -262,6 +263,7 @@ void dxt_posix_write(darshan_record_id rec_id, int64_t offset,
     rec_ref->write_traces[file_rec->write_count].length = length;
     rec_ref->write_traces[file_rec->write_count].start_time = start_time;
     rec_ref->write_traces[file_rec->write_count].end_time = end_time;
+    annotate_trace_segment(rec_ref->write_traces[file_rec->write_count].extra_info);
     file_rec->write_count += 1;
 
     DXT_UNLOCK();
@@ -307,6 +309,7 @@ void dxt_posix_read(darshan_record_id rec_id, int64_t offset,
     rec_ref->read_traces[file_rec->read_count].length = length;
     rec_ref->read_traces[file_rec->read_count].start_time = start_time;
     rec_ref->read_traces[file_rec->read_count].end_time = end_time;
+    annotate_trace_segment(rec_ref->read_traces[file_rec->read_count].extra_info);
     file_rec->read_count += 1;
 
     DXT_UNLOCK();
@@ -352,6 +355,7 @@ void dxt_mpiio_write(darshan_record_id rec_id, int64_t offset,
     rec_ref->write_traces[file_rec->write_count].offset = offset;
     rec_ref->write_traces[file_rec->write_count].start_time = start_time;
     rec_ref->write_traces[file_rec->write_count].end_time = end_time;
+    annotate_trace_segment(rec_ref->write_traces[file_rec->write_count].extra_info);
     file_rec->write_count += 1;
 
     DXT_UNLOCK();
@@ -397,6 +401,7 @@ void dxt_mpiio_read(darshan_record_id rec_id, int64_t offset,
     rec_ref->read_traces[file_rec->read_count].offset = offset;
     rec_ref->read_traces[file_rec->read_count].start_time = start_time;
     rec_ref->read_traces[file_rec->read_count].end_time = end_time;
+    annotate_trace_segment(rec_ref->read_traces[file_rec->read_count].extra_info);
     file_rec->read_count += 1;
 
     DXT_UNLOCK();
@@ -760,6 +765,23 @@ static struct dxt_file_record_ref *dxt_mpiio_track_new_file_record(
     return(rec_ref);
 }
 
+void annotate_trace_segment(char *extra_info_str)
+{
+    char *extra_info_env = getenv("DARSHAN_DXT_EXTRA_INFO");
+    if (extra_info_env != NULL) {
+        strncpy(extra_info_str, extra_info_env, EXTRA_INFO_LEN-1);
+    } else {
+        extra_info_str[0] = '\0';
+    }
+    unsigned long pthread_id = (unsigned long)pthread_self();
+    if(strlen(extra_info_str))
+        strcat(extra_info_str, " ");
+    snprintf(extra_info_str + strlen(extra_info_str), EXTRA_INFO_LEN-1-strlen(extra_info_str),
+        "pthread_id=%lu", pthread_id);
+
+    return;
+}
+
 static void dxt_free_record_data(void *rec_ref_p, void *user_ptr)
 {
     struct dxt_file_record_ref *dxt_rec_ref = (struct dxt_file_record_ref *)rec_ref_p;
diff --git a/darshan-util/darshan-dxt-logutils.c b/darshan-util/darshan-dxt-logutils.c
index af1520e38..950c024e9 100644
--- a/darshan-util/darshan-dxt-logutils.c
+++ b/darshan-util/darshan-dxt-logutils.c
@@ -294,6 +294,7 @@ void dxt_log_print_posix_file(void *posix_file_rec, char *file_name,
     int64_t length;
     double start_time;
     double end_time;
+    char *extra_info;
     int i, j;
 
     darshan_record_id f_id = file_rec->base_rec.id;
@@ -362,8 +363,9 @@ void dxt_log_print_posix_file(void *posix_file_rec, char *file_name,
         length = io_trace[i].length;
         start_time = io_trace[i].start_time;
         end_time = io_trace[i].end_time;
+        extra_info = io_trace[i].extra_info;
 
-        printf("%8s%8" PRId64 "%7s%9d%16" PRId64 "%16" PRId64 "%12.4f%12.4f   ", "X_POSIX", rank, "write", i, offset, length, start_time, end_time);
+        printf("%8s%8" PRId64 "%7s%9d%16" PRId64 "%16" PRId64 "%12.4f%12.4f\t%s", "X_POSIX", rank, "write", i, offset, length, start_time, end_time, extra_info);
 
         if (lustreFS) {
             cur_file_offset = offset;
@@ -408,8 +410,9 @@ void dxt_log_print_posix_file(void *posix_file_rec, char *file_name,
         length = io_trace[i].length;
         start_time = io_trace[i].start_time;
         end_time = io_trace[i].end_time;
+        extra_info = io_trace[i].extra_info;
 
-        printf("%8s%8" PRId64 "%7s%9d%16" PRId64 "%16" PRId64 "%12.4f%12.4f   ", "X_POSIX", rank, "read", (int)(i - write_count), offset, length, start_time, end_time);
+        printf("%8s%8" PRId64 "%7s%9d%16" PRId64 "%16" PRId64 "%12.4f%12.4f\t%s", "X_POSIX", rank, "read", (int)(i - write_count), offset, length, start_time, end_time, extra_info);
 
         if (lustreFS) {
             cur_file_offset = offset;
@@ -461,6 +464,7 @@ void dxt_log_print_mpiio_file(void *mpiio_file_rec, char *file_name,
     int64_t offset;
     double start_time;
     double end_time;
+    char * extra_info;
     int i;
 
     darshan_record_id f_id = file_rec->base_rec.id;
@@ -489,8 +493,10 @@ void dxt_log_print_mpiio_file(void *mpiio_file_rec, char *file_name,
         length = io_trace[i].length;
         start_time = io_trace[i].start_time;
         end_time = io_trace[i].end_time;
+        extra_info = io_trace[i].extra_info;
+        if (extra_info == NULL) extra_info = "";
 
-        printf("%8s%8" PRId64 "%7s%9d%16" PRId64 "%16" PRId64 "%12.4f%12.4f\n", "X_MPIIO", rank, "write", i, offset, length, start_time, end_time);
+        printf("%8s%8" PRId64 "%7s%9d%16" PRId64 "%16" PRId64 "%12.4f%12.4f\t%s\n", "X_MPIIO", rank, "write", i, offset, length, start_time, end_time, extra_info);
     }
 
     for (i = write_count; i < write_count + read_count; i++) {
@@ -499,7 +505,7 @@ void dxt_log_print_mpiio_file(void *mpiio_file_rec, char *file_name,
         start_time = io_trace[i].start_time;
         end_time = io_trace[i].end_time;
 
-        printf("%8s%8" PRId64 "%7s%9d%16" PRId64 "%16" PRId64 "%12.4f%12.4f\n", "X_MPIIO", rank, "read", (int)(i - write_count), offset, length, start_time, end_time);
+        printf("%8s%8" PRId64 "%7s%9d%16" PRId64 "%16" PRId64 "%12.4f%12.4f\t%s\n", "X_MPIIO", rank, "read", (int)(i - write_count), offset, length, start_time, end_time, extra_info);
     }
 
     return;
diff --git a/darshan-util/pydarshan/darshan/backend/api_def_c.py b/darshan-util/pydarshan/darshan/backend/api_def_c.py
index d0cb6be3a..b457f5096 100644
--- a/darshan-util/pydarshan/darshan/backend/api_def_c.py
+++ b/darshan-util/pydarshan/darshan/backend/api_def_c.py
@@ -205,6 +205,7 @@
     int64_t length;
     double start_time;
     double end_time;
+    char extra_info[64];
 } segment_info;
 
 /* counter names */
diff --git a/darshan-util/pydarshan/darshan/backend/cffi_backend.py b/darshan-util/pydarshan/darshan/backend/cffi_backend.py
index 34fcfa580..52fed0bdd 100644
--- a/darshan-util/pydarshan/darshan/backend/cffi_backend.py
+++ b/darshan-util/pydarshan/darshan/backend/cffi_backend.py
@@ -626,7 +626,8 @@ def log_get_dxt_record(log, mod_name, reads=True, writes=True, dtype='dict'):
             "offset": segments[i].offset,
             "length": segments[i].length,
             "start_time": segments[i].start_time,
-            "end_time": segments[i].end_time
+            "end_time": segments[i].end_time,
+            "extra_info": ffi.string(segments[i].extra_info).decode("utf-8")
         }
         rec['write_segments'].append(seg)
 
@@ -637,7 +638,8 @@ def log_get_dxt_record(log, mod_name, reads=True, writes=True, dtype='dict'):
             "offset": segments[i].offset,
             "length": segments[i].length,
             "start_time": segments[i].start_time,
-            "end_time": segments[i].end_time
+            "end_time": segments[i].end_time,
+            "extra_info": ffi.string(segments[i].extra_info).decode("utf-8")
         }
         rec['read_segments'].append(seg)
 
diff --git a/include/darshan-dxt-log-format.h b/include/darshan-dxt-log-format.h
index b31fc9928..5f40ae837 100644
--- a/include/darshan-dxt-log-format.h
+++ b/include/darshan-dxt-log-format.h
@@ -10,6 +10,7 @@
 #define DXT_POSIX_VER 1
 #define DXT_MPIIO_VER 2
 
+#define EXTRA_INFO_LEN 64
 #define HOSTNAME_SIZE 64
 
 /*
@@ -21,6 +22,7 @@ typedef struct segment_info {
     int64_t length;
     double start_time;
     double end_time;
+    char extra_info[EXTRA_INFO_LEN];
 } segment_info;
 
 #define X(a) a,