performance comparison results

			PERFORMANCE COMPARISON AMONG dm-cache, bcache and EnhanceIO
			============================================================

The fio config and setup information follows:
HDD              : 100GB
SSD              :  20GB
Mode             : write through / write back
Cache block_size : 4KB for bcache, EnhanceIO and 256KB for dm-cache

The other options have been left to their default values.

Note:
1) In case of dm-cache, we used 2 partitions of same SSD with 1GB partition as metadata and 20GB
partition as caching device. This has been done so as to ensure a fair comparison as EnhanceIO and
bcache do not have a separate metadata device.

2) In order to ensure proper cache warm up, We have turned off sequential bypass in bcache. This 
does not impact our performance results as they are taken for random workload.

For each test, we first performed a warm up run using the following fio options:
fio --direct=1 --size=90% --filesize=20G --blocksize=4k --ioengine=libaio --rw=rw --rwmixread=100 
--rwmixwrite=0 --iodepth=8 ...

Then, we performed our actual run with the following fio options:
fio --direct=1 --size=100% --filesize=20G --blocksize=4k --ioengine=libaio --rw=randrw --rwmixread=90
--rwmixwrite=10 --iodepth=8 --numjobs=4 --random_distribution=zipf:1.2 ...

				WRITE THROUGH MODE TEST RESULTS
				===============================
EnhanceIO-mode-wt
-----------------------------------------------------------------------
Iteration 		Read Latency ms		Write Latency ms	Read MB/s	Write MB/s
1			1.58			16.21			32.86		3.65
2			1.58			16.35			32.7		3.63
3			1.58			16.54			32.56		3.61
4			1.59			16.6			32.48		3.6
5			1.58			16.58			32.57		3.61
Standard deviation	0.004472136		0.1694992625		0.1489295135	0.02
Mean			1.582			16.456			32.634		3.62


dm-cache-HDD-100G-SSD-20G-mode-wt-io-4K-read-90-write-10-hits-90-ram-48G
-------------------------------------------------------------------------
Iteration 		Read Latency ms		Write Latency ms	Read MB/s	Write MB/s
1			0.86			31.04			23.96		2.65
2			0.31			28.01			29.58		3.28
3			0.39			28.67			28.48		3.16
4			0.39			29.15			29.46		3.27
5			0.28			27.94			29.72		3.3
Standard deviation	0.2364952431		1.2638710377		2.4418435658	0.2748999818
Mean			0.446			28.962			28.24		3.132


bcache-HDD-100G-SSD-20G-mode-wt-io-4K-read-90-write-10-hits-90-ram-48G
-----------------------------------------------------------------------
Iteration 		Read Latency ms		Write Latency ms	Read MB/s	Write MB/s
1			0.56			31.08			27.03		3
2			0.61			30			30.7		3.4
3			0.57			29.36			30.72		3.41
4			0.6			30.02			29.79		3.3
5			0.93			35.65			25.55		2.83
Standard Deviation	0.1556598856		2.5511017228		2.343239211	0.2599423013
Mean			0.654			31.222			28.758		3.188

				WRITE BACK MODE TEST RESULTS
				============================
EnhanceIO-mode-wb
-------------------------------------------------------------------
Iteration 		Read Latency ms		Write Latency ms	Read MB/s	Write MB/s
1			0.33			4.69			145.11		16.14
2			0.33			4.64			146.06		16.23
3			0.33			4.62			146.72		16.3
4			0.33			4.65			145.99		16.2
5			0.33			4.72			144.25		16.02
Standard Deviation	0			0.0403732585		0.9588169794	0.1054514106
Mean			0.33			4.664			145.626		16.178


dm-cache-mode-wb
-------------------------------------------------------------------------
Iteration 		Read Latency ms		Write Latency ms	Read MB/s	Write MB/s
1			1.02			2.42			94.49		10.5
2			1.69			4.97			53.89		5.98
3			1.11			2.72			86.2		9.56
4			0.53			0.52			208.54		23.16
5			1.6			4.11			59.47		6.61
Standard Deviation	0.4714339827		1.7076797124		62.7877437881	6.9737091996
Mean			1.19			2.948			100.518		11.162


bcache-mode-wb
----------------------------------------------------------------------
Iteration 		Read Latency ms		Write Latency ms	Read MB/s	Write MB/s
1			0.95			1.67			108.08		12
2			0.97			1.63			106.77		11.86
3			0.97			1.61			106.99		11.88
4			1			1.5			104.93		11.66
5			0.94			1.67			107.47		11.95
Standard Deviation	0.0230217289		0.0698569968		1.1842381517	0.13
Mean			0.966			1.616			106.848		11.87

Note:The scripts used for these tests can be found at:
     https://github.com/stec-inc/EnhanceIO/tree/master/performance_test