So, the options are:

- use the existing code
- use the C version
- use Charles' untested table version

Are there strong objections to going to C versions?  In all likelihood
the runqueue will be redesigned for different schedulers and to improve
the performance on multiprocessor systems anyway.

Charles M. Hannum wrote:

> Basically, I mean the following patch, although I haven't tested it
> yet:
> 
> Index: locore.s
> ===================================================================
> RCS file: /cvsroot/syssrc/sys/arch/i386/i386/locore.s,v
> retrieving revision 1.258
> diff -u -r1.258 locore.s
> --- locore.s	2002/08/28 09:47:16	1.258
> +++ locore.s	2002/10/23 16:28:43
> @@ -1667,6 +1667,40 @@
>  	.globl	_C_LABEL(sched_whichqs),_C_LABEL(sched_qs)
>  	.globl	_C_LABEL(uvmexp),_C_LABEL(panic)
>  
> +powerof2:
> +	.long	0x00000001
> +	.long	0x00000002
> +	.long	0x00000004
> +	.long	0x00000008
> +	.long	0x00000010
> +	.long	0x00000020
> +	.long	0x00000040
> +	.long	0x00000080
> +	.long	0x00000100
> +	.long	0x00000200
> +	.long	0x00000400
> +	.long	0x00000800
> +	.long	0x00001000
> +	.long	0x00002000
> +	.long	0x00004000
> +	.long	0x00008000
> +	.long	0x00010000
> +	.long	0x00020000
> +	.long	0x00040000
> +	.long	0x00080000
> +	.long	0x00100000
> +	.long	0x00200000
> +	.long	0x00400000
> +	.long	0x00800000
> +	.long	0x01000000
> +	.long	0x02000000
> +	.long	0x04000000
> +	.long	0x08000000
> +	.long	0x10000000
> +	.long	0x20000000
> +	.long	0x40000000
> +	.long	0x80000000
> +
>  /*
>   * void setrunqueue(struct proc *p);
>   * Insert a process on the appropriate queue.  Should be called at splclock().
> @@ -1684,9 +1718,10 @@
>  	jne	1f
>  #endif /* DIAGNOSTIC */
>  	movzbl	P_PRIORITY(%eax),%edx
> -	shrl	$2,%edx
> -	btsl	%edx,_C_LABEL(sched_whichqs)	# set q full bit
> -	leal	_C_LABEL(sched_qs)(,%edx,8),%edx # locate q hdr
> +	andl	$-4,%edx
> +	movl	powerof2(%edx),%ecx
> +	orl	%ecx,_C_LABEL(sched_whichqs)	# set q full bit
> +	leal	_C_LABEL(sched_qs)(%edx,%edx),%edx # locate q hdr
>  	movl	P_BACK(%edx),%ecx
>  	movl	%edx,P_FORW(%eax)	# link process on tail of q
>  	movl	%eax,P_BACK(%edx)
> @@ -1710,9 +1745,10 @@
>  	movl	4(%esp),%ecx
>  	movzbl	P_PRIORITY(%ecx),%eax
>  #ifdef DIAGNOSTIC
> -	shrl	$2,%eax
> -	btl	%eax,_C_LABEL(sched_whichqs)
> -	jnc	1f
> +	andl	$-4,%eax
> +	movl	powerof2(%eax),%eax
> +	andl	_C_LABEL(sched_whichqs),%eax
> +	jz	1f
>  #endif /* DIAGNOSTIC */
>  	movl	P_BACK(%ecx),%edx	# unlink process
>  	movl	$0,P_BACK(%ecx)		# zap reverse link to indicate off list
> @@ -1722,9 +1758,10 @@
>  	cmpl	%ecx,%edx		# q still has something?
>  	jne	2f
>  #ifndef DIAGNOSTIC
> -	shrl	$2,%eax
> +	andl	$-4,%eax
> +	movl	powerof2(%eax),%eax
>  #endif
> -	btrl	%eax,_C_LABEL(sched_whichqs)	# no; clear bit
> +	subl	%eax,_C_LABEL(sched_whichqs)	# no; clear bit
>  2:	ret
>  #ifdef DIAGNOSTIC
>  1:	pushl	$3f

	-- Gregory McGarry <g.mcgarry@ieee.org>