diff --git a/README.md b/README.md
index 0095767..ff8ca57 100644
--- a/README.md
+++ b/README.md
@@ -7,4 +7,56 @@ Use spdlog as log tool and the default level is 'info'.
 
 ### Features
 
-* Fast - 
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+* Fast - with the same number of threads `FastDup` is ~3.5X faster than GATK MarkDuplicatesSpark.
+  And `FastDup` achives ~15X performance improvement than Picard MarkDuplicates.
+* Generate identical outputs compared to Picard MarkDuplicates.
+* The same detailed metrics data witch Picard MarkDuplicates.
+* All data processed in memory and low-memory footprint even for large input files. 
+
+### Limitations
+
+* Although `FastDup` can detecte all the same duplicates as Picard MarkDuplicates. They may mark 
+  different reads as duplicates because the reads sort algorithm in Picard MarkDuplicates is unstable.
+  Considering there are 2 reads(A, B and A is in front of B in file) in a duplicate group and they
+  have the same score, Picard Markduplicates may mark A as duplicate because B may be in front of A
+  after sorting. While `FastDup` use stable sort algorithm and always mark B as duplicate.
+* In optical duplicates detection, Picard Markduplicates use short (int16_t) as data type in parsing 
+  tile/region, x coordinate and y coordinate from a read name, which may data overflow as these integers
+  may exceed the range of short type. `FastDup` fixes this bug. But for consistency with Picard Markduplicates,
+  we keep this bug in source codes. Just change the data type in PhysicalLocation struct in read_ends.h file
+  to fix this bug.
+* `FastDup` use the data characteristics in coordinate ordered SAM/BAM files to improve the performance of
+  detecting duplicates, thus the input should be ordered by coordinate in advance.
+
+## Requirements
+
+### Build tools
+
+* cmake
+* c++17 (gcc >= 8.1 or clang >= 7 should work.)
+
+### Libraries need
+
+* zlib
+* libbz2
+* liblzma
+* libcurl
+* libdeflate (optional)
+
+## Install
+
+Download a distribution tarball `FastDup.tar.gz` or clone the source codes from github.
+
+```
+# build htslib
+cd FastDup/ext/htslib
+autoreconf -i
+./configure
+make
+
+# build FastDup
+cd FastDup
+mkdir build && cd build
+cmake .. -DCMAKE_BUILD_TYPE=Release
+make && sudo make install
+```
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diff --git a/metrics.txt b/metrics.txt
deleted file mode 100644
index bb5ff03..0000000
--- a/metrics.txt
+++ /dev/null
@@ -1,111 +0,0 @@
-## StringHeader
-# /home/zzh/work/ngs/FastDup/build/bin/fastdup --input /home/zzh/data/bam/normal_all.sam --output /home/zzh/data1/out.sam --metrics ./metrics.txt --num-threads 1 --create-index --index-format CSI --tag-duplicate-set-members
-## StringHeader
-# Started on: December 16, 2024 at 02:43:41 AM CST
-
-## METRICS
-LIBRARY	UNPAIRED_READS_EXAMINED	READ_PAIRS_EXAMINED	SECONDARY_OR_SUPPLEMENTARY_RDS	UNMAPPED_READS	UNPAIRED_READ_DUPLICATES	READ_PAIR_DUPLICATES	READ_PAIR_OPTICAL_DUPLICATES	PERCENT_DUPLICATION	ESTIMATED_LIBRARY_SIZE
-normal	108919	66154888	117508	161395	67414	15058359	876584	0.227945	127582703
-
-## HISTOGRAM	Double
-BIN CoverageMult
-1	1.010249
-2	1.611750
-3	1.969882
-4	2.183113
-5	2.310070
-6	2.385660
-7	2.430666
-8	2.457463
-9	2.473417
-10	2.482917
-11	2.488573
-12	2.491940
-13	2.493945
-14	2.495139
-15	2.495850
-16	2.496273
-17	2.496525
-18	2.496675
-19	2.496764
-20	2.496817
-21	2.496849
-22	2.496868
-23	2.496879
-24	2.496886
-25	2.496890
-26	2.496892
-27	2.496894
-28	2.496894
-29	2.496895
-30	2.496895
-31	2.496895
-32	2.496896
-33	2.496896
-34	2.496896
-35	2.496896
-36	2.496896
-37	2.496896
-38	2.496896
-39	2.496896
-40	2.496896
-41	2.496896
-42	2.496896
-43	2.496896
-44	2.496896
-45	2.496896
-46	2.496896
-47	2.496896
-48	2.496896
-49	2.496896
-50	2.496896
-51	2.496896
-52	2.496896
-53	2.496896
-54	2.496896
-55	2.496896
-56	2.496896
-57	2.496896
-58	2.496896
-59	2.496896
-60	2.496896
-61	2.496896
-62	2.496896
-63	2.496896
-64	2.496896
-65	2.496896
-66	2.496896
-67	2.496896
-68	2.496896
-69	2.496896
-70	2.496896
-71	2.496896
-72	2.496896
-73	2.496896
-74	2.496896
-75	2.496896
-76	2.496896
-77	2.496896
-78	2.496896
-79	2.496896
-80	2.496896
-81	2.496896
-82	2.496896
-83	2.496896
-84	2.496896
-85	2.496896
-86	2.496896
-87	2.496896
-88	2.496896
-89	2.496896
-90	2.496896
-91	2.496896
-92	2.496896
-93	2.496896
-94	2.496896
-95	2.496896
-96	2.496896
-97	2.496896
-98	2.496896
-99	2.496896
-100	2.496896
diff --git a/src/markdup/markdup.cpp b/src/markdup/markdup.cpp
index 37067a6..97d552a 100644
--- a/src/markdup/markdup.cpp
+++ b/src/markdup/markdup.cpp
@@ -303,7 +303,7 @@ int MarkDuplicates() {
                 bam_aux_append(bw->b, "PG", 'Z', nsgv::gMdArg.PROGRAM_RECORD_ID.size() + 1,
                                (const uint8_t *)nsgv::gMdArg.PROGRAM_RECORD_ID.c_str());
             }
-#if 0
+#if 1
             if (sam_write1(nsgv::gOutBamFp, nsgv::gOutBamHeader, bw->b) < 0) {
                 spdlog::error("failed writing sam record to \"{}\"", nsgv::gMdArg.OUTPUT_FILE.c_str());
                 sam_close(nsgv::gOutBamFp);
diff --git a/src/markdup/md_args.cpp b/src/markdup/md_args.cpp
deleted file mode 100644
index dfb4fda..0000000
--- a/src/markdup/md_args.cpp
+++ /dev/null
@@ -1,26 +0,0 @@
-/*
-Description: Markduplicate需要用到的一些参数，读取命令行给的参数，并做一些初始化
-
-Copyright : All right reserved by ICT
-
-Author : Zhang Zhonghai
-Date : 2023/10/27
-*/
-
-#include <cstring>
-#include <iostream>
-#include <sstream>
-#include <string>
-#include <vector>
-
-#include "md_args.h"
-using std::cout, std::endl;
-
-using std::ostringstream;
-using std::stod;
-using std::stoi;
-using std::stol;
-using std::string;
-using std::vector;
-
-using namespace nsmd;
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