On 2018-01-31 01:23, Ming Lei wrote:
Hi All,
After KPTI is merged, there is extra load introduced to context switch
between user space and kernel space. It is observed on my laptop that
one
syscall takes extra ~0.15us[1] compared with 'nopti'.
IO performance is affected too, it is observed that IOPS drops by 32%
in
my test[2] on null_blk compared with 'nopti':
randread IOPS on latest linus tree:
-------------------------------------------------
| randread IOPS | randread IOPS with 'nopti'|
------------------------------------------------
| 928K | 1372K |
------------------------------------------------
Do you know if your CPU has PCID? It would be interesting to see these
tests on older CPUs or older kernels without PCID support.
