On 2016-02-03 3:53 PM, francismb wrote:
Hi,
On 02/01/2016 10:43 PM, Yury Selivanov wrote:
We also need to deoptimize the code to avoid having too many cache
misses/pointless cache updates. I found that, for instance, LOAD_ATTR
is either super stable (hits 100% of times), or really unstable, so 20
misses is, again, seems to be alright.
Aren't those hits/misses a way to see how dynamic the code is? I mean
can't the current magic (manually tweaked on a limited set) values,
be self tweaked/adapted on those numbers?
Probably.
One way of tackling this is to give each optimized opcode
a counter for hit/misses. When we have a "hit" we increment
that counter, when it's a miss, we decrement it.
I kind of have something like that right now:
https://github.com/1st1/cpython/blob/opcache5/Python/ceval.c#L3035
But I only decrement that counter -- the idea is that LOAD_ATTR
is allowed to "miss" only 20 times before getting deoptimized.
I'll experiment with inc/dec on hit/miss and see how that affects
the performance.
An ideal way would be to calculate a hit/miss ratio over time
for each cached opcode, but that would be an expensive
calculation.
Yury
_______________________________________________
Python-Dev mailing list
Python-Dev@python.org
https://mail.python.org/mailman/listinfo/python-dev
Unsubscribe:
https://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
