The kernel’s print function, printk(), has been the target of
numerous improvement efforts over the years for a
variety of reasons. One persistent problem with printk() has been
that its latency is unacceptably high for the realtime Linux kernel; at
this point, printk() represents the last piece needing changes
before the
RT_PREEMPT patches can be fully merged. So there have been efforts
to rework printk() for latency and lots of other reasons, but
those have not made it into the mainline; a recent discussion at
the 2022 Linux Plumbers Conference (LPC)
seems to have paved the way for new solution to land in the mainline before
too long.

Source: LWN.net – [$] A discussion on printk()