[bitcoin-dev] Block Compression (Datastream Compression) test results using the PR#6973 compression prototype

[Peter Tschipper <peter.tschipper@gmail.com>]

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Some further Block Compression tests results that compare performance
when network latency is added to the mix.

Running two nodes, windows 7, compressionlevel=6, syncing the first
200000 blocks from one node to another.  Running on a highspeed wireless
LAN with no connections to the outside world.
Network latency was added by using Netbalancer to induce the 30ms and
60ms latencies.

From the data not only are bandwidth savings seen but also a small
performance savings as well.  However, the overall the value in
compressing blocks appears to be in terms of saving bandwidth.  

I was also surprised to see that there was no real difference in
performance when no latency was present; apparently the time it takes to
compress is about equal to the performance savings in such a situation.


The following results compare the tests in terms of how long it takes to
sync the blockchain, compressed vs uncompressed and with varying latencies.
uncmp = uncompressed
cmp = compressed

num blocks sync'd 	uncmp (secs) 	cmp (secs) 	uncmp 30ms (secs) 	cmp 30ms
(secs) 	uncmp 60ms (secs) 	cmp 60ms (secs)
10000 	264 	269 	265 	257 	274 	275
20000 	482 	492 	479 	467 	499 	497
30000 	703 	717 	693 	676 	724 	724
40000 	918 	939 	902 	886 	947 	944
50000 	1140 	1157 	1114 	1094 	1171 	1167
60000 	1362 	1380 	1329 	1310 	1400 	1395
70000 	1583 	1597 	1547 	1526 	1637 	1627
80000 	1810 	1817 	1767 	1745 	1872 	1862
90000 	2031 	2036 	1985 	1958 	2109 	2098
100000 	2257 	2260 	2223 	2184 	2385 	2355
110000 	2553 	2486 	2478 	2422 	2755 	2696
120000 	2800 	2724 	2849 	2771 	3345 	3254
130000 	3078 	2994 	3356 	3257 	4125 	4006
140000 	3442 	3365 	3979 	3870 	5032 	4904
150000 	3803 	3729 	4586 	4464 	5928 	5797
160000 	4148 	4075 	5168 	5034 	6801 	6661
170000 	4509 	4479 	5768 	5619 	7711 	7557
180000 	4947 	4924 	6389 	6227 	8653 	8479
190000 	5858 	5855 	7302 	7107 	9768 	9566
200000 	6980 	6969 	8469 	8220 	10944 	10724



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