linux-gcp: Reduce boot latency due to RAID6_PQ
Affects | Status | Importance | Assigned to | Milestone | |
---|---|---|---|---|---|
linux-gcp (Ubuntu) |
Fix Released
|
Undecided
|
Marcelo Cerri | ||
Bionic |
Fix Released
|
Undecided
|
Marcelo Cerri |
Bug Description
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.
CVE References
Changed in linux-gcp (Ubuntu Bionic): | |
status: | In Progress → Fix Committed |
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