Does ISA Matter for Performance?

When I grew up with computers, the big RISC vs CISC debate was raging. At the time, in the late 1980s, it did indeed seem that RISC was inherently superior to CISC. SPARCs, MIPS, and Alpha all outpaced boring old x86, VAX and 68000 processors. This turned out to be a historical parenthesis, as the Pentium Pro from Intel showed how RISC-style performance could be mated to a CISC ISA. However, maybe ISAs still do matter.

Continue reading “Does ISA Matter for Performance?”

Memory Models: x86 is TSO, TSO is Good

By chance, I got to attend a day at the UPMARC Summer School with a very enjoyable talk by Francesco Zappa Nardelli from INRIA. He described his work (along with others) on understanding and modeling multiprocessor memory models. It is a very complex subject, but he managed to explain it very well.

Continue reading “Memory Models: x86 is TSO, TSO is Good”