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** Changed in: linux (Ubuntu)
       Status: New => Incomplete

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https://bugs.launchpad.net/bugs/2039576

Title:
  Enabling CONFIG_CRYPTO_STATS causes significant fscrypt performance
  degradation

Status in linux package in Ubuntu:
  Incomplete

Bug description:
  CONFIG_CRYPTO_STATS is enabled in Jammy 5.15.0-xx as well as 6.2.0-xx
  kernel by default.

  # uname -r
  5.15.0-69-generic
  root@r100:~# grep CONFIG_CRYPTO_STATS /boot/config-5.15.0-69-generic
  CONFIG_CRYPTO_STATS=y

  However, that CONFIG_CRYPTO_STATS makes big negative performance impacts.
  Lustre (http://www.lustre.com Open source parallel filesystem) supports 
client encryption based on fscrypt.
  I ran some benchmarks of Lustre client encryption on Lustre client with 
Ubuntu 6.2.0-34-generic kernel below.

  1 x client(2 x Gold 6438Y+, 512GB RAM, 2 x HDR200)
  Ubuntu22.04 (6.2.0-34-generic) 

  # fio -name=iotest-w -ioengine=sync -rw=write -blocksize=16m
  -iodepth=1 -direct=1 -fallocate=none -size=200g -numjobs=128
  -group_reporting -directory=/lustre/encrypted -create_serialize=0
  -fiename_format='f.$jobnum.$filenum' -scramble_buffers=0 -runtime=60

  6.2.0-34-generic, no encryption           48.5GB/s
  6.2.0-34-generic, encryption              21.7GB/s
  6.2.0-34-generic-noCryptStats, encryption 48.2GB/s

  When Lustre client encryption enabled, there were 65% performance 
degradations compared to non encryption's performance. (21.7GB/s vs 48.5GB/s)
  I also tested on 6.2.0-34-generic-noCryptStats which I built custom 
6.2.0-34-generic kernel with disabling CONFIG_CRYPTO_STATS.
  The result was pretty good. The performance did boost and it was almost same 
speed against non encryption case. (48.2GB/s vs 48.5GB/s)

  I also found same fscrypt performance problem reported in Ceph with RHEL 
kernel below.
  
https://lists.ceph.io/hyperkitty/list/ceph-us...@ceph.io/thread/44GMO5UGOXDZKFSOQMCPPHYTREUEA3ZI/

  Eventually, Redhat disabled CONFIG_CRYPTO_STATS in latest RHEL9 kernel
  
https://gitlab.com/redhat/centos-stream/src/kernel/centos-stream-9/-/merge_requests/2947
  Kernel config option CONFIG_CRYPTO_STATS should be disabled until it is 
enhanced (BZ#2231850) - https://access.redhat.com/errata/RHSA-2023:5069

  I would disable CONFIG_CRYPTO_STATS in all Jammy kernels until proper
  fixes and new solution is available in upstream kernel.

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