Recent slowdown in single object builds

[Jens Axboe]

Hi,

I've noticed that current -git is a lot slower at doing single object
builds than earlier kernels. Here's an example, building the exact same
file on 5.2 and -git:

$ time make fs/io_uring.o
real    0m5.953s
user    0m5.402s
sys     0m0.649s

vs 5.2 based (with all the backports, identical file):

$ time make fs/io_uring.o
real    0m3.218s
user    0m2.968s
sys     0m0.520s

Any idea what's going on here? It's almost twice as slow, which is
problematic...

-- 
Jens Axboe