add pospopcount conclusion bug #672

diff --git a/openpower/sv/cookbook/pospopcnt.mdwn b/openpower/sv/cookbook/pospopcnt.mdwn
index cec72685f7a70a18fd5afcc84e17f722c9febf5e..d3db8bb422a8b56b322cbb3a6708994a526740cb 100644 (file)
--- a/openpower/sv/cookbook/pospopcnt.mdwn
+++ b/openpower/sv/cookbook/pospopcnt.mdwn
@@ -226,4 +226,23 @@ of straight accumulators `r16-r23`.  However this starts to push
 the boundaries of the number of registers needed, so as an
 exercise is left for another time.
 
+# Conclusion
+
+Where a normal SIMD ISA requires explicit hand-crafted optimisation
+in order to achieve full utilisation of the underlying hardware,
+Simple-V instead can rely to a large extent on standard Multi-Issue
+hardware to achieve similar performance, whilst crucially keeping the
+algorithm implementation down to a shockingly-simple degree that makes
+it easy to understand an easy to review.  Again also as with many
+other algorithms when implemented in Simple-V SVP54, by keeping to
+a LOAD-COMPUTE-STORE paradigm the L1 Data Cache usage is minimised,
+and in this case just as with chacha20 the entire algorithm, being
+only 9 lines of assembler fitting into 13 4-byte words it can fit
+into a single L1 I-Cache Line without triggering Virtual Memory TLB
+misses.
+
+Further performance improvements are achievable by using REMAP
+Parallel Reduction, still fitting into a single L1 Cache line,
+but beginning to approach the limit of the 128-long register file.
+
 [[!tag svp64_cookbook ]]