Re: Has anyone produced a board using Kicad?


DJ Delorie wrote:
fpga_toys@xxxxxxxxx writes:
It really needs to be the same tool,

Or at least *seem* like it's the same tool. Otherwise, I agree.

On larger designs, memory is being pushed to maintain lists and objects
instantiated already. Paging severely cuts into performance. When
running as a separate application, there is substantial page
replication introduced for every data page for a long list of shared
library instances, plus replication of the netlists. Likewise,
performance is critially tied to working set, having a second
application running concurrently with equally large working set, will
provoke substantial cache thrashing, which will show up as memory
latency induced jerkyness in the UI, as the cache is flushed out and
reloaded between contexts. While these may seem like parameters in the
application architecture that can be ignored, perceived UI performance
is heavily dependent on them. Similarly the communication between
separate applications results in context switches, which causes
additional cache thrashing by including large sections of the kernel in
the working set. Consider the processor is some 20-100 times faster
than L2/L3 cache these days, and the cache is frequently another 10-50
times or more faster than memory. Exceeding cache working sets,
effectively turns the machine into a 50MHz processor again.

There are substantial performance reasons suggesting that it should be
the same application, (just a different thread at most) to conserve
memory resources, and improve performance. While they may not be
critical for toy student projects, for many real life projects which
are much larger, they become critical UI problems. The sample
ProofOfConcept design I sent you, is about 1/5 the size of several
production designs I have done using PCB.

When the typical desktop CPU comes standard with 10MB or better of L2
cache, these issues might go away. Last time I checked, this was only
available for high end Itianum processors, well outside the reach of
most mortals in cost (or me right now).

.

Relevant Pages

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