5 ms·

Compared to "no encryption", a S4 mini (Dual-core 1.7 GHz. 1.5 GB RAM) is almost unusable (~30 seconds to switch to an app that's stale, i.e. not one of the las

by cnvogel 11y ago

Compared to "no encryption", a S4 mini (Dual-core 1.7 GHz. 1.5 GB RAM) is almost unusable (~30 seconds to switch to an app that's stale, i.e. not one of the last few apps used) under Cyanogenmod 12.1 with full disk encryption on. Without encryption is was ~"ok" to use, not fast, but bearable.

bad_user 11y ago
When speaking of disk encryption the bottleneck is the CPU. In order for encryption to work without a noticeable performance hit you need a microprocessor with hardware acceleration for AES. For example the latest Intel and AMD processors have the AES-NI instruction set. Ditto for the latest Qualcomm Snapdragon SoC. I'm not sure if hardware acceleration is enabled in Nexus 6, but the hardware is certainly capable of acceleration. I now have an encrypted Nexus 6 and the performance is fine. My previous Nexus 4 was also encrypted and after encryption the performance hit was noticeable when booting up, but after boot it performs fine. 30 seconds to switch an app that's stale sounds like there's something really wrong either with your device or with the Cyanogenmod version you've got installed, judging by those specs at least.
- m45t3r 11y ago
  In modern processors the bottleneck generally is the IO. While it is not the same think (desktop vs phone processors), this author benchmarks OpenSSL in an algorithm similar that Android uses, with and without AES-NI (Intel HW encryption): https://mjanja.ch/2013/11/disabling-aes-ni-on-linux-openssl/ https://mjanja.ch/2013/11/disabling-aes-ni-on-linux-openssl/. Even without AES-NI, this processor is doing more than 100MB/s of encryption. Mobile storage is a lot worse than this (like less than 50MB/s in sustained sequential writes), and you have to remember this would be the worst case (since the majority of writes for common users is small files instead of big files). Just to put in perspective: my Moto X can write around ~20MB/s when transferring files by USB 2.0. And it can still write the same ~20MB/s with encryption on.

by cnvogel 11y ago

bad_user 11y ago

When speaking of disk encryption the bottleneck is the CPU. In order for encryption to work without a noticeable performance hit you need a microprocessor with hardware acceleration for AES. For example the latest Intel and AMD processors have the AES-NI instruction set. Ditto for the latest Qualcomm Snapdragon SoC. I'm not sure if hardware acceleration is enabled in Nexus 6, but the hardware is certainly capable of acceleration. I now have an encrypted Nexus 6 and the performance is fine. My previous Nexus 4 was also encrypted and after encryption the performance hit was noticeable when booting up, but after boot it performs fine. 30 seconds to switch an app that's stale sounds like there's something really wrong either with your device or with the Cyanogenmod version you've got installed, judging by those specs at least.

m45t3r 11y ago
In modern processors the bottleneck generally is the IO. While it is not the same think (desktop vs phone processors), this author benchmarks OpenSSL in an algorithm similar that Android uses, with and without AES-NI (Intel HW encryption): https://mjanja.ch/2013/11/disabling-aes-ni-on-linux-openssl/ https://mjanja.ch/2013/11/disabling-aes-ni-on-linux-openssl/. Even without AES-NI, this processor is doing more than 100MB/s of encryption. Mobile storage is a lot worse than this (like less than 50MB/s in sustained sequential writes), and you have to remember this would be the worst case (since the majority of writes for common users is small files instead of big files). Just to put in perspective: my Moto X can write around ~20MB/s when transferring files by USB 2.0. And it can still write the same ~20MB/s with encryption on.