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Optimize cpu_switchto to store the new PCB address in r7, rather than

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loading it from memory in 3 places.

Also adjust ordering of a few loads to try and avoid stalling.
This commit is contained in:
chris 2008-01-19 16:49:42 +00:00
parent 19884cbfe6
commit 1c0a934301
1 changed files with 29 additions and 39 deletions
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68
sys/arch/arm/arm32/cpuswitch.S
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@ -1,4 +1,4 @@
/* $NetBSD: cpuswitch.S,v 1.54 2008/01/19 15:04:10 chris Exp $ */
/* $NetBSD: cpuswitch.S,v 1.55 2008/01/19 16:49:42 chris Exp $ */
/*
* Copyright 2003 Wasabi Systems, Inc.
@ -154,9 +154,15 @@ ENTRY(cpu_switchto)
mov ip, sp
stmfd sp!, {r4-r7, ip, lr}
mov r6, r1 /* save new lwp */
mov r4, r0 /* save old lwp, it's the return value */
/* move lwps and new pcb into caller saved registers */
mov r6, r1
mov r4, r0
ldr r7, [r6, #(L_ADDR)]
/* rem: r4 = old lwp */
/* rem: r6 = new lwp */
/* rem: r7 = new pcb */
IRQdisable
#ifdef MULTIPROCESSOR
@ -167,20 +173,19 @@ ENTRY(cpu_switchto)
/* l->l_cpu initialized in fork1() for single-processor */
#endif
/* We have a new curlwp now so make a note it */
ldr r7, .Lcurlwp
str r6, [r7]
/* We have a new curlwp and pcb so make a note of them */
ldr r0, .Lcurlwp
ldr r1, .Lcurpcb
/* Hook in a new pcb */
ldr r7, .Lcurpcb
ldr r0, [r6, #(L_ADDR)]
str r0, [r7]
str r6, [r0]
str r7, [r1]
/* At this point we can allow IRQ's again. */
IRQenable
/* rem: r4 = old lwp */
/* rem: r6 = new lwp */
/* rem: r7 = new pcb */
/* rem: interrupts are enabled */
/*
@ -190,26 +195,26 @@ ENTRY(cpu_switchto)
* straight to restoring the context for the new process.
*/
teq r4, #0x00000000
ldreq r9, [r6, #(L_ADDR)]
beq .Ldo_switch
/* rem: r4 = old lwp */
/* rem: r6 = new lwp */
/* rem: r7 = new pcb */
/* rem: interrupts are enabled */
/* Save old context */
/* Get the user structure for the old lwp. */
ldr r1, [r4, #(L_ADDR)]
ldr r5, [r4, #(L_ADDR)]
/* Save all the registers in the old lwp's pcb */
#ifndef __XSCALE__
add r7, r1, #(PCB_R8)
stmia r7, {r8-r13}
add r0, r5, #(PCB_R8)
stmia r0, {r8-r13}
#else
strd r8, [r1, #(PCB_R8)]
strd r10, [r1, #(PCB_R10)]
strd r12, [r1, #(PCB_R12)]
strd r8, [r5, #(PCB_R8)]
strd r10, [r5, #(PCB_R10)]
strd r12, [r5, #(PCB_R12)]
#endif
/*
@ -217,28 +222,16 @@ ENTRY(cpu_switchto)
* them for the new process.
*/
/* rem: r1 = old lwp PCB */
/* rem: r4 = old lwp */
/* rem: r5 = old pcb */
/* rem: r6 = new lwp */
/* rem: r7 = new pcb */
/* rem: interrupts are enabled */
/* Remember the old PCB. */
mov r8, r1
/* r1 now free! */
/* Get the user structure for the new process in r9 */
ldr r9, [r6, #(L_ADDR)]
/* What else needs to be saved? Only FPA stuff when that is supported */
/* Restore saved context */
/* rem: r4 = old lwp */
/* rem: r6 = new lwp */
/* rem: r9 = new PCB */
/* rem: interrupts are enabled */
.Ldo_switch:
mov r0, r4
mov r1, r6
@ -246,17 +239,16 @@ ENTRY(cpu_switchto)
/* rem: r4 = old lwp */
/* rem: r6 = new lwp */
/* rem: r9 = new PCB */
/* rem: r7 = new pcb */
/* rem: interrupts are enabled */
ldr r5, [r6, #(L_PROC)] /* fetch the proc for below */
/* Restore all the saved registers */
#ifndef __XSCALE__
add r7, r9, #PCB_R8
ldmia r7, {r8-r13}
sub r7, r7, #PCB_R8 /* restore PCB pointer */
add r0, r7, #PCB_R8
ldmia r0, {r8-r13}
#else
mov r7, r9
ldr r8, [r7, #(PCB_R8)]
ldr r9, [r7, #(PCB_R9)]
ldr r10, [r7, #(PCB_R10)]
@ -265,8 +257,6 @@ ENTRY(cpu_switchto)
ldr r13, [r7, #(PCB_SP)]
#endif
ldr r5, [r6, #(L_PROC)] /* fetch the proc for below */
/* rem: r4 = old lwp */
/* rem: r5 = new lwp's proc */
/* rem: r6 = new lwp */