CVS commit: src/sys/arch

["Taylor R Campbell" <riastradh%netbsd.org@localhost>]

Module Name:    src
Committed By:   riastradh
Date:           Sat Feb 25 18:04:42 UTC 2023

Modified Files:
        src/sys/arch/amd64/amd64: genassym.cf locore.S
        src/sys/arch/x86/x86: fpu.c

Log Message:
x86: Add kthread_fpu_enter/exit support, take two.

This time, make sure to restore the FPU state when switching to a
kthread in the middle of kthread_fpu_enter/exit.

This adds a single predicted-taken branch for the case of kthreads
that are not in kthread_fpu_enter/exit, so it incurs a penalty only
for threads that actually use it.  Since it avoids FPU state
switching in kthreads that do use the FPU, namely cgd worker threads,
this should be a net performance win on systems using it and have
negligible impact otherwise.

XXX pullup-10


To generate a diff of this commit:
cvs rdiff -u -r1.93 -r1.94 src/sys/arch/amd64/amd64/genassym.cf
cvs rdiff -u -r1.215 -r1.216 src/sys/arch/amd64/amd64/locore.S
cvs rdiff -u -r1.81 -r1.82 src/sys/arch/x86/x86/fpu.c

Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.