Rod Pemberton <
noe...@basdxcqvbe.com> writes:
>
>Hey guys, I'm curious, what features do you look for in an x86
>processor?
>
>How would you rank the following in terms of importance for a
>processor's performance?
>
>clock speed
>cache size
>unlocked cores
>number of cores
>
>I would probably rank them as listed above.
It's entirely dependent up on the desired workload.
Clock speed is a curious thing, most processors today
have multiple clocks (a base board clock, then clocks
for ethernet PHYs, various I/O controllers (e.g. SPI, MMC),
and the cores which are derived from the base board clock
via programmable multipliers which can be independenly
and dynamically adjusted in real-time).
I'd be looking to ensure the ISA supports the needs
of the desired workload (i.e. are SIMD instructions
required? 128-bit? 256-bit? 512-bit SIMD? Does the
cpu support the non-deterministic random number
generation instructions - important for crypto workloads?)
DDR speeds are also significant - does the memory controller
in the chip support DDR4? DDR5? How many transactions/sec?
Is the workload single threaded? Higher clock speeds
or highly optimized cores may be best. Otherwise, how
parallelizable the workload is defines the requisite
core count.
Bus width - does the application require more than 2^40,
2^44, 2^48 or 2^52 bits of address space for memory and/or
add-in PCI express devices?
Do the memory controllers support ECC? A system without ECC
is useless for most real-world workloads.