cvs commit: src/sys/conf options.i386 src/sys/i386/i386machdep.c mp_machdep.c pmap.c swtch.s src/sys/i386/include md_var.h pmap.h smp.h src/sys/i386/isa apic_vector.s intr_machdep.h src/sys/kern kern_switch.c kern_synch.c kern_thr.c kern_thread.c subr_witness.c ...

[Nate Lawson]

On Wed, 2 Apr 2003, Peter Wemm wrote:
>   Commit a partial lazy thread switch mechanism for i386.  it isn't as lazy
>   as it could be and can do with some more cleanup.  Currently its under
>   options LAZY_SWITCH.  What this does is avoid %cr3 reloads for short
>   context switches that do not involve another user process.

This is awesome!

>   One non-trivial change was to select a new thread before calling
>   cpu_switch() in the first place.  This allows us to catch the silly
>   case of doing a cpu_switch() to the current process.  This happens
>   uncomfortably often.  This simplifies a bit of the asm code in cpu_switch
>   (no longer have to call choosethread() in the middle).  This has been
>   implemented on i386 and (thanks to jake) sparc64.  The others will come
>   soon.  This is actually seperate to the lazy switch stuff.

Shouldn't there be a "if (thread == curthread) return;" in the scheduling
code somewhere?

-Nate