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dm-crypt mount delay experiment February 27, 2007

Posted by TSAI HONG-BIN in Linux.
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Obviously encrypted loopback files require more time to complete mount/umount operations. It seems that no matter how big the encrypted loopback file is, the delay is always approximately 0.72 second. I’ve made a loopback file in 1G, and it’s mount delay is around 0.72 as well. Security is always a trade-off of performance, however.

The experiment is run on an Intel core duo 1.86G platform with 1G RAM.

encrypted loopback file           
1st round (in seconds)                                            16M      64M     256M
losetup + cryptsetup luksOpen + mount            0.722    0.72    0.734
umount + cryptsetup luksClose + losetup          0.011    0.011    0.011

2nd round                                                                0.733    0.714    0.713
0.012    0.011    0.01

3rd round                                                                  0.72    0.72    0.72
0.01    0.011    0.011

Average                                                                    0.725     0.718     0.722
0.011    0.011    0.010666667

 

native loopback file       
1st round (in seconds)                                    16M      64M      256M
mount                                                                0.007    0.006    0.007
umount                                                              0.003    0.003    0.004

2nd round                                                         0.007    0.006    0.006
0.005    0.004    0.003

3rd round                                                          0.007    0.006    0.006
0.003    0.004    0.003

average                                                             0.007    0.006    0.0063
0.0037    0.0037    0.0033

 

 

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