linux-gcp: Reduce boot latency due to RAID6_PQ

[Marcelo Cerri]

For an n1-standard-2 with ubuntu-1604, we spend around 600 milliseconds during boot on computing the best raid6 recovery algorithm seen in the following lines of the kernel logs:

...
[ 2.216022] raid6: sse2x1 gen() 8570 MB/s
[ 2.264029] raid6: sse2x1 xor() 6467 MB/s
[ 2.312030] raid6: sse2x2 gen() 10602 MB/s
[ 2.360021] raid6: sse2x2 xor() 6999 MB/s
[ 2.412028] raid6: sse2x4 gen() 12483 MB/s
[ 2.464022] raid6: sse2x4 xor() 8607 MB/s
[ 2.516024] raid6: avx2x1 gen() 16712 MB/s
[ 2.568020] raid6: avx2x1 xor() 12050 MB/s
[ 2.620019] raid6: avx2x2 gen() 19393 MB/s
[ 2.672024] raid6: avx2x2 xor() 12406 MB/s
[ 2.724034] raid6: avx2x4 gen() 22330 MB/s
[ 2.776029] raid6: avx2x4 xor() 15196 MB/s
[ 2.780440] raid6: using algorithm avx2x4 gen() 22330 MB/s
[ 2.786035] raid6: .... xor() 15196 MB/s, rmw enabled
[ 2.791196] raid6: using avx2x2 recovery algorithm
...

It would be desirable to reduce or eliminate this delay.

[Marcelo Cerri (mhcerri)]

Test kernel: https://kernel.ubuntu.com/~mhcerri/lp1812728_v1/

Patchset on the mailing list: https://lists.ubuntu.com/archives/kernel-team/2019-January/098018.html

[Launchpad Janitor (janitor)]

This bug was fixed in the package linux-gcp - 4.15.0-1028.29~16.04.1

---------------
linux-gcp (4.15.0-1028.29~16.04.1) xenial; urgency=medium

  * linux-gcp: 4.15.0-1028.29~16.04.1 -proposed tracker (LP: #1814744)

  * Packaging resync (LP: #1786013)
    - [Packaging] update helper scripts

  [ Ubuntu: 4.15.0-1028.29 ]

  * linux-gcp: 4.15.0-1028.29 -proposed tracker (LP: #1814734)
  * linux-gcp: Reduce boot latency due to RAID6_PQ (LP: #1812728)
    - SAUCE: raid6: Add option for default PQ algorithm
    - [config] linux-gcp: CONFIG_RAID6_PQ_DEFAULT_ALG="avx2x4"
  * linux: 4.15.0-46.49 -proposed tracker (LP: #1814726)
  * mprotect fails on ext4 with dax (LP: #1799237)
    - x86/speculation/l1tf: Exempt zeroed PTEs from inversion
  * kernel BUG at /build/linux-vxxS7y/linux-4.15.0/mm/slub.c:296! (LP: #1812086)
    - iscsi target: fix session creation failure handling
    - scsi: iscsi: target: Set conn->sess to NULL when iscsi_login_set_conn_values
      fails
    - scsi: iscsi: target: Fix conn_ops double free
  * user_copy in user from ubuntu_kernel_selftests failed on KVM kernel
    (LP: #1812198)
    - selftests: user: return Kselftest Skip code for skipped tests
    - selftests: kselftest: change KSFT_SKIP=4 instead of KSFT_PASS
    - selftests: kselftest: Remove outdated comment
  * RTL8822BE WiFi Disabled in Kernel 4.18.0-12 (LP: #1806472)
    - SAUCE: staging: rtlwifi: allow RTLWIFI_DEBUG_ST to be disabled
    - [Config] CONFIG_RTLWIFI_DEBUG_ST=n
    - SAUCE: Add r8822be to signature inclusion list
  * kernel oops in bcache module (LP: #1793901)
    - SAUCE: bcache: never writeback a discard operation
  * CVE-2018-18397
    - userfaultfd: use ENOENT instead of EFAULT if the atomic copy user fails
    - userfaultfd: shmem: allocate anonymous memory for MAP_PRIVATE shmem
    - userfaultfd: shmem/hugetlbfs: only allow to register VM_MAYWRITE vmas
    - userfaultfd: shmem: add i_size checks
    - userfaultfd: shmem: UFFDIO_COPY: set the page dirty if VM_WRITE is not set
  * Ignore "incomplete report" from Elan touchpanels (LP: #1813733)
    - HID: i2c-hid: Ignore input report if there's no data present on Elan
      touchpanels
  * Vsock connect fails with ENODEV for large CID (LP: #1813934)
    - vhost/vsock: fix vhost vsock cid hashing inconsistent
  * SRU: Fix thinkpad 11e 3rd boot hang (LP: #1804604)
    - ACPI / LPSS: Force LPSS quirks on boot
  * Bionic update: upstream stable patchset 2019-01-17 (LP: #1812229)
    - scsi: sd_zbc: Fix variable type and bogus comment
    - KVM/Eventfd: Avoid crash when assign and deassign specific eventfd in
      parallel.
    - x86/apm: Don't access __preempt_count with zeroed fs
    - x86/events/intel/ds: Fix bts_interrupt_threshold alignment
    - x86/MCE: Remove min interval polling limitation
    - fat: fix memory allocation failure handling of match_strdup()
    - ALSA: hda/realtek - Add Panasonic CF-SZ6 headset jack quirk
    - ARCv2: [plat-hsdk]: Save accl reg pair by default
    - ARC: Fix CONFIG_SWAP
    - ARC: configs: Remove CONFIG_INITRAMFS_SOURCE from defconfigs
    - ARC: mm: allow mprotect to make stack mappings executable
    - mm: memcg: fix use after free in mem_cgroup_iter()
   ...

[Launchpad Janitor (janitor)]

This bug was fixed in the package linux-gcp - 4.15.0-1028.29

---------------
linux-gcp (4.15.0-1028.29) bionic; urgency=medium

  * linux-gcp: 4.15.0-1028.29 -proposed tracker (LP: #1814734)

  * linux-gcp: Reduce boot latency due to RAID6_PQ (LP: #1812728)
    - SAUCE: raid6: Add option for default PQ algorithm
    - [config] linux-gcp: CONFIG_RAID6_PQ_DEFAULT_ALG="avx2x4"

  [ Ubuntu: 4.15.0-46.49 ]

  * linux: 4.15.0-46.49 -proposed tracker (LP: #1814726)
  * mprotect fails on ext4 with dax (LP: #1799237)
    - x86/speculation/l1tf: Exempt zeroed PTEs from inversion
  * kernel BUG at /build/linux-vxxS7y/linux-4.15.0/mm/slub.c:296! (LP: #1812086)
    - iscsi target: fix session creation failure handling
    - scsi: iscsi: target: Set conn->sess to NULL when iscsi_login_set_conn_values
      fails
    - scsi: iscsi: target: Fix conn_ops double free
  * user_copy in user from ubuntu_kernel_selftests failed on KVM kernel
    (LP: #1812198)
    - selftests: user: return Kselftest Skip code for skipped tests
    - selftests: kselftest: change KSFT_SKIP=4 instead of KSFT_PASS
    - selftests: kselftest: Remove outdated comment
  * RTL8822BE WiFi Disabled in Kernel 4.18.0-12 (LP: #1806472)
    - SAUCE: staging: rtlwifi: allow RTLWIFI_DEBUG_ST to be disabled
    - [Config] CONFIG_RTLWIFI_DEBUG_ST=n
    - SAUCE: Add r8822be to signature inclusion list
  * kernel oops in bcache module (LP: #1793901)
    - SAUCE: bcache: never writeback a discard operation
  * CVE-2018-18397
    - userfaultfd: use ENOENT instead of EFAULT if the atomic copy user fails
    - userfaultfd: shmem: allocate anonymous memory for MAP_PRIVATE shmem
    - userfaultfd: shmem/hugetlbfs: only allow to register VM_MAYWRITE vmas
    - userfaultfd: shmem: add i_size checks
    - userfaultfd: shmem: UFFDIO_COPY: set the page dirty if VM_WRITE is not set
  * Ignore "incomplete report" from Elan touchpanels (LP: #1813733)
    - HID: i2c-hid: Ignore input report if there's no data present on Elan
      touchpanels
  * Vsock connect fails with ENODEV for large CID (LP: #1813934)
    - vhost/vsock: fix vhost vsock cid hashing inconsistent
  * SRU: Fix thinkpad 11e 3rd boot hang (LP: #1804604)
    - ACPI / LPSS: Force LPSS quirks on boot
  * Bionic update: upstream stable patchset 2019-01-17 (LP: #1812229)
    - scsi: sd_zbc: Fix variable type and bogus comment
    - KVM/Eventfd: Avoid crash when assign and deassign specific eventfd in
      parallel.
    - x86/apm: Don't access __preempt_count with zeroed fs
    - x86/events/intel/ds: Fix bts_interrupt_threshold alignment
    - x86/MCE: Remove min interval polling limitation
    - fat: fix memory allocation failure handling of match_strdup()
    - ALSA: hda/realtek - Add Panasonic CF-SZ6 headset jack quirk
    - ARCv2: [plat-hsdk]: Save accl reg pair by default
    - ARC: Fix CONFIG_SWAP
    - ARC: configs: Remove CONFIG_INITRAMFS_SOURCE from defconfigs
    - ARC: mm: allow mprotect to make stack mappings executable
    - mm: memcg: fix use after free in mem_cgroup_iter()
    - mm/huge_memory.c: fix data loss when splitting a file pmd
    - cpufreq: intel_pstate: Register when ACPI PCCH is present
    - vfio/pci: Fix potential Spectre v1...