On Mar 13, 2009, at 5:06 PM, Kumar Gala wrote:
On Mar 13, 2009, at 4:26 PM, Benjamin Herrenschmidt wrote:
+BEGIN_FTR_SECTION
+ b TlbWo /* Code for TLB-errata workaround doesn't fit
here */
+END_FTR_SECTION_IFSET(CPU_FTR_NEED_DTLB_SW_LRU)
+RFTlbWo:
Can you use nicer label names ? :-)
Also, that's a lot of code for such a hot path...
Cheers,
Ben.
The code needs reworking. However, we are doing SW LRU, not sure
how we reduce this in the hot path.
Ben, David,
Here's my attempt at reworking the code to use an SPRG, remove
branches, optimize it down, etc. I haven't validated that this is
even correct. It should be easy to replace the m{f,t}spr SPRG w/lwz/
stw if we want to keep the LRU state in memory instead.
Ben, do you think we can optimize this further with some random LRU
selection?
mtspr SPRN_RPA,r1
mfspr r2,SPRN_SRR1 /* Need to restore CR0 */
mtcrf 0x80,r2
#if 1
li r0,1
mfspr r1,SPRN_SPRG4 /* could replace w/lwz
r1,sw_way_...@l(0) */
rlwinm r3,r3,19,25,29 /* Get Address bits 19:15 */
slw r0,r0,r3
xor r1,r0,r1
srw r0,r1,r3
mtspr SPRN_SPRG4,r1 /* could replace w/stw
r1,sw_way_...@l(0) */
rlwimi r2,r0,31-14,14,14
#endif
tlbld r3
rfi
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