Delay time increased on HLS Streaming

We use HLS streaming for live video, we would like to decrease delay time to real time, so we choose chunkLength=2s in command to EvoStream.
Results : As long as it’s displaying stream video, it delays more.
For example, when it starts display, it delays 8s. After a while, it delays 14s -> 18s -> 26s -> 35s -> 55s … then the HLS player skip frames and back to delay 8s -> 14s -> … Could you help to check this issue more ?
I guess the issue comes from playlist.m3u8 ? It looks like 2 seconds in real video that will be displayed/created in ~ 3 seconds of TS files. So as long as it’s displaying stream video, the difference is longer. This also happen for different chunkLength 10s, 6s, 4s. We always set I-Frame Interval = 1s. More details about content of m3u8 file : Case 1 : chunkLength=2 chunkOnIDR=1 #EXTM3U
#EXT-X-VERSION:3
#EXT-X-ALLOW-CACHE:NO
#EXT-X-TARGETDURATION:4
#EXT-X-MEDIA-SEQUENCE:557
#EXT-X-PROGRAM-DATE-TIME:2016-10-26T12:00:01.996+00:00
#EXTINF:3.167,
segment_1477481591484_557.ts
#EXTINF:3.050,
segment_1477481591484_558.ts
#EXTINF:3.117,
segment_1477481591484_559.ts
#EXTINF:2.717,
segment_1477481591484_560.ts
#EXTINF:3.050,
segment_1477481591484_561.ts
#EXTINF:2.667,
segment_1477481591484_562.ts
#EXTINF:3.050,
segment_1477481591484_563.ts
#EXTINF:2.800,
segment_1477481591484_564.ts
#EXTINF:3.017,
segment_1477481591484_565.ts
#EXTINF:2.800,
segment_1477481591484_566.ts Case 2 : chunkLength=2 chunkOnIDR=0 #EXTM3U
#EXT-X-VERSION:3
#EXT-X-ALLOW-CACHE:NO
#EXT-X-TARGETDURATION:3
#EXT-X-MEDIA-SEQUENCE:486
#EXT-X-PROGRAM-DATE-TIME:2016-10-27T04:37:36.584+00:00
#EXTINF:2.000,
segment_1477542075837_486.ts
#EXTINF:2.000,
segment_1477542075837_487.ts
#EXTINF:2.000,
segment_1477542075837_488.ts
#EXTINF:2.000,
segment_1477542075837_489.ts
#EXTINF:2.100,
segment_1477542075837_490.ts
#EXTINF:2.000,
segment_1477542075837_491.ts
#EXTINF:2.000,
segment_1477542075837_492.ts
#EXTINF:2.000,
segment_1477542075837_493.ts
#EXTINF:2.000,
segment_1477542075837_494.ts
#EXTINF:1.800,
segment_1477542075837_495.ts
#EXT-X-ENDLIST