6 ms·

Another reason is that read/write speeds on APFS encrypted volumes are 30-40% slower than non-encrypted volumes[1]. [1] https://news.ycombinator.com/item?id=15

by Osiris 9y ago

Another reason is that read/write speeds on APFS encrypted volumes are 30-40% slower than non-encrypted volumes[1]. [1] https://news.ycombinator.com/item?id=15333036 https://news.ycombinator.com/item?id=15333036

nrki 9y ago
Speed in MB/s HFS+ HFS+ Encrypted APFS APFS Encrypted 1M WRITE 1375 1373 1372 933 1M READ 2446 2340 2162 1304 4K WRITE 852 797 502 378 4K READ 2106 1486 2156 1001 https://news.ycombinator.com/item?id=15333754 https://news.ycombinator.com/item?id=15333754
- mikeash 9y ago
  That's really strange. Why would encryption affect APFS so badly but not HFS+?
  - convivialdingo 9y ago
    Lots of reasons. If crypto is part of the syscall path, then you definitely pay with latency. If you can push IO to a worker thread then you can release the user call faster. This also requires tuning the read-ahead cache more aggressively. It could also be a change in crypto algorithm, unaligned page IO, or any other overlooked IO latency problems.
  - j45 9y ago
    At a high level, I believe APFS encrypts files individually (and uniquely) instead of the whole drive. Have to do some more reading :)
    - Someone 9y ago
      Not instead of, but optionally in addition to (https://developer.apple.com/library/content/documentation/FileManagement/Conceptual/APFS_Guide/Features/Features.html https://developer.apple.com/library/content/documentation/Fi...) On Mac OS, it seems you only get full disk encryption, though (https://arstechnica.com/gadgets/2017/09/macos-10-13-high-sierra-the-ars-technica-review/6/ https://arstechnica.com/gadgets/2017/09/macos-10-13-high-sie...)
      - j45 9y ago
        Appreciate the clarification. Both are better than just one.
- zitterbewegung 9y ago
  This was high sierra beta though.
ringaroundthetx 9y ago
Just curious, at these speeds, what use case would really affect you, or people you can imagine? 30-40% in a stress test is significant. but if I'm not editing 4k videos perhaps, where would I notice this? Even amongst us programmers who use horrible inefficient IDEs and make horrible inefficient electron apps, disk speed isn't really a noticeable bottleneck right now? Even a convoluted local environment to simulate a server environment with a ton of microservices wouldn't really be affected much by this
- finnh 9y ago
  Disk speed is always a bottleneck, much more than CPU generally. Almost every thing you do leads to, or is dependent on, IO speeds. If you disk speed drops by 40%, for example, every application will be at least 40% slower to load. That's a major hit. That horribly inefficient electron app is now slow to load, not just slow to run. Or, to put this another way: Do you have an SSD? Why?
  - frou_dh 9y ago
    The filesystem is cached in RAM so it’s too simplistic to talk about applications like that.
  - ringaroundthetx 9y ago
    yeah, not always true, and this is more about noticeable performance. The answer is to why I have an SSD is speed and throughput and the point of calling this file system change out is because there are diminishing returns to the productivity in real world use a benchmark is just a repeated process which is not reflective or real world use except in very small narrowly tailored applications
bouke 9y ago
As the speed test was using a beta of High Sierra / APFS, I performed some tests of my own. I've written /dev/zero to the disk, and read Xcode_9_GM_seed.xip from the disk using different block sizes using `dd`. I ran the read tests a few times, as there was a lot variation in the results. I've excluded the first result of the read results for each FS. The test was run on a Samsung Evo Pro 850 500GB SSD inside a Sharkoon USB-C case connected over USB-C to a MacBook Pro 2016 w/ Touchbar. Speed in MB/s HFS+ HFS+ Encrypted APFS APFS Encrypted 1M write 498 473 490 (-2%) 444 (-6%) 1M read 6896 6815 6860 (-1%) 6827 (0%) 4k write 486 477 485 (-0%) 445 (-7%) 4k read 2734 2709 2599 (-5%) 2545 (-6%) While there is still some performance degradation between HFS+ and APFS, it's within a single digit now.
- stirner 9y ago
  dd is not an acceptable benchmark. You need to eliminate the effects of buffering/caching to get accurate results.
  - Someone1234 9y ago
    /dev/zero is also not an acceptable source of data; since \0\0\0\0\etc is unnaturally easy to compress. A large real file (e.g. installation ISO) may have been a better idea.
- bouke 9y ago
  Following the comments on the test method, I've run the 'Blackmagic Disk Speed Test'. The results are the following. Speed in MB/s HFS+ HFS+ Encrypted APFS APFS Encrypted read 513 513 508 506 write 477 460 478 432 The earlier results of 7 GB/s are quite impossible with the Samsung Evo Pro 850 -- those max out around 500 MB/s. So my earlier test results are invalid. The new test results mostly show that both file systems can saturate the disk's raw throughput. -- update On my internal Apple SSD (PCI-Express) I've created a partition for testing. I've kept "Blackmagic Disk Speed Test" running for a few minutes and took an average of the tests. The results are in favor of APFS, beating HFS+ by 3-17% in throughput. Speed in MB/s HFS+ HFS+ Encrypted APFS APFS Encrypted read 2400 2240 2700 (+13%) 2400 (+7%) write 1900 1930 2000 (+5%) 1980 (+3%)
timcederman 9y ago
Just tested this. Was consistently getting 2000mb/s+ writes before, now getting ~1600mb/s. Reads are inconsistent, but most results are also 20-40% slower than before.

by Osiris 9y ago

nrki 9y ago

Speed in MB/s HFS+ HFS+ Encrypted APFS APFS Encrypted 1M WRITE 1375 1373 1372 933 1M READ 2446 2340 2162 1304 4K WRITE 852 797 502 378 4K READ 2106 1486 2156 1001 https://news.ycombinator.com/item?id=15333754 https://news.ycombinator.com/item?id=15333754

mikeash 9y ago
That's really strange. Why would encryption affect APFS so badly but not HFS+?
- convivialdingo 9y ago
  Lots of reasons. If crypto is part of the syscall path, then you definitely pay with latency. If you can push IO to a worker thread then you can release the user call faster. This also requires tuning the read-ahead cache more aggressively. It could also be a change in crypto algorithm, unaligned page IO, or any other overlooked IO latency problems.
- j45 9y ago
  At a high level, I believe APFS encrypts files individually (and uniquely) instead of the whole drive. Have to do some more reading :)
  - Someone 9y ago
    Not instead of, but optionally in addition to (https://developer.apple.com/library/content/documentation/FileManagement/Conceptual/APFS_Guide/Features/Features.html https://developer.apple.com/library/content/documentation/Fi...) On Mac OS, it seems you only get full disk encryption, though (https://arstechnica.com/gadgets/2017/09/macos-10-13-high-sierra-the-ars-technica-review/6/ https://arstechnica.com/gadgets/2017/09/macos-10-13-high-sie...)
    - j45 9y ago
      Appreciate the clarification. Both are better than just one.
zitterbewegung 9y ago
This was high sierra beta though.

ringaroundthetx 9y ago

Just curious, at these speeds, what use case would really affect you, or people you can imagine? 30-40% in a stress test is significant. but if I'm not editing 4k videos perhaps, where would I notice this? Even amongst us programmers who use horrible inefficient IDEs and make horrible inefficient electron apps, disk speed isn't really a noticeable bottleneck right now? Even a convoluted local environment to simulate a server environment with a ton of microservices wouldn't really be affected much by this

finnh 9y ago
Disk speed is always a bottleneck, much more than CPU generally. Almost every thing you do leads to, or is dependent on, IO speeds. If you disk speed drops by 40%, for example, every application will be at least 40% slower to load. That's a major hit. That horribly inefficient electron app is now slow to load, not just slow to run. Or, to put this another way: Do you have an SSD? Why?
- frou_dh 9y ago
  The filesystem is cached in RAM so it’s too simplistic to talk about applications like that.
- ringaroundthetx 9y ago
  yeah, not always true, and this is more about noticeable performance. The answer is to why I have an SSD is speed and throughput and the point of calling this file system change out is because there are diminishing returns to the productivity in real world use a benchmark is just a repeated process which is not reflective or real world use except in very small narrowly tailored applications

bouke 9y ago

As the speed test was using a beta of High Sierra / APFS, I performed some tests of my own. I've written /dev/zero to the disk, and read Xcode_9_GM_seed.xip from the disk using different block sizes using `dd`. I ran the read tests a few times, as there was a lot variation in the results. I've excluded the first result of the read results for each FS. The test was run on a Samsung Evo Pro 850 500GB SSD inside a Sharkoon USB-C case connected over USB-C to a MacBook Pro 2016 w/ Touchbar. Speed in MB/s HFS+ HFS+ Encrypted APFS APFS Encrypted 1M write 498 473 490 (-2%) 444 (-6%) 1M read 6896 6815 6860 (-1%) 6827 (0%) 4k write 486 477 485 (-0%) 445 (-7%) 4k read 2734 2709 2599 (-5%) 2545 (-6%) While there is still some performance degradation between HFS+ and APFS, it's within a single digit now.

stirner 9y ago
dd is not an acceptable benchmark. You need to eliminate the effects of buffering/caching to get accurate results.
- Someone1234 9y ago
  /dev/zero is also not an acceptable source of data; since \0\0\0\0\etc is unnaturally easy to compress. A large real file (e.g. installation ISO) may have been a better idea.
bouke 9y ago
Following the comments on the test method, I've run the 'Blackmagic Disk Speed Test'. The results are the following. Speed in MB/s HFS+ HFS+ Encrypted APFS APFS Encrypted read 513 513 508 506 write 477 460 478 432 The earlier results of 7 GB/s are quite impossible with the Samsung Evo Pro 850 -- those max out around 500 MB/s. So my earlier test results are invalid. The new test results mostly show that both file systems can saturate the disk's raw throughput. -- update On my internal Apple SSD (PCI-Express) I've created a partition for testing. I've kept "Blackmagic Disk Speed Test" running for a few minutes and took an average of the tests. The results are in favor of APFS, beating HFS+ by 3-17% in throughput. Speed in MB/s HFS+ HFS+ Encrypted APFS APFS Encrypted read 2400 2240 2700 (+13%) 2400 (+7%) write 1900 1930 2000 (+5%) 1980 (+3%)

timcederman 9y ago

Just tested this. Was consistently getting 2000mb/s+ writes before, now getting ~1600mb/s. Reads are inconsistent, but most results are also 20-40% slower than before.