whether we're talking dollars in your bank account items on a seafood buffet
or dates you've got lined up on tinder more is generally considered to be
better a sentiment that also seems to hold true with the number of cores in
your computer CPU at least if you buy into the marketing hold on even though
having many cores definitely gives you a boost in multi-threaded applications
like rendering 3d animations there are
actually situations where more cores gives no benefit whatsoever or can even
actually hurt your system's performance
but how could this be well to start off with the more cores
you pack onto a CPU the more power they need and the more heat they generate and
remember that because CPU cores are crammed into a relatively small space
manufacturers end up working against some serious limits when it comes to
thermal design power or TDP this means that to prevent the CPU from
drawing too much power and producing too much heat the individual cores have
traditionally run their clock frequencies lower to improve efficiency
and even if the advertised boost clock for a CPU with lots and lots of course
can appear to be high it's often the case that they cannot
maintain these clocks for long periods of time or that they only do it when
you're running very light applications so if you're using your computer mostly
for applications where single threaded performance matters more such as games
that super expensive 18 core CPU might
actually yield you a worse experience than something cheaper
and if you go with a really high core count CPU there's another wrinkle with
how processors with that many cores access the system memory you see in some
cases these larger cpus need to have their core split into two groups or
nodes of course with each group getting its own memory controller and segment of
the physical memory in a scheme called non-uniform memory access or pneuma
this is generally quicker than the opposite solution called uniform memory
access or yuma where all the cores share
one big pool of memory but here's the thing a CPU that uses pneuma which is
better for latency sensitive applications can often struggle when
running a single program that uses tons of threads
because of the different memory access times between the nodes and the fact
that each node would have to wait on the other one to finish working on the same
data highly multi-threaded programs like these often don't want to cross nodes
even if it would mean being able to take advantage of the entire CPU
so back to yuma then right no
because one controller manages all the memory accesses to give every program
equal time rather than allowing access to the memory more directly as in numa
yuma has a built-in performance penalty
that increases the more nodes your system has to manage
so using a CPU with separate groups of cores means you're going to be subjected
to one of these drawbacks and you're going to take a performance hit either
way and these are problems that you simply don't run into on smaller chips
with fewer cores because you're not dealing with multiple nodes
but getting away from memory access sometimes the cores themselves are even
designed in a way that bottlenecks them the more of them you slap onto a chip do
you remember how before ryzen AMD processors seemed to be significantly
slower than Intel despite having more cores
well a big reason for this was that those old bulldozer fx processors didn't
use full cores instead an fx CPU advertised as having a
cores would in reality have eight integer units but only four floating
point units that were shared between the eight cores so if you don't know what a
floating point unit is you can learn more about that right up here but the point is you could think of these cpus
as having four half cores that were missing which
severely hampered their single threaded performance in some key applications
now this design allowed AMD processors to handle more threads for a cheaper
price but it also meant that their real-world performance legged way behind
Intel and the only way AMD could try and compensate was to increase clock speeds
which increased heat output and contributed to AMD's reputation for hot
running cpus for many years so what's our bottom line then although both AMD
and Intel are using much wiser strategies for their many core cpus and
clever boosting techniques to give them similar single threaded performance to
their less costly brethren if the best sales pitch for a super
premium product is that it doesn't suffer a performance penalty in the
applications that you use well you'd better make sure you've got a use
case for it before spending your hard earned cash and no playing fortnight and
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