Dmitriy,
I agree, hashFunctionScore is more comprehensible.
I'd correct it to "pageHashFunctionScore" to make it clear that it's
about function that distributes pages, not about hashCode() of
user-provided keys.
--
Best Regards,
Ivan Rakov
On 18.07.2017 19:34, Dmitriy Setrakyan wrote:
Ivan,
How about renaming it to hashFunctionScore? This will be more digestable to
users. "segmentFillVariance" sounds too scientific even to me.
D.
On Tue, Jul 18, 2017 at 10:39 AM, Ivan Rakov <ivan.glu...@gmail.com> wrote:
Hello Igniters,
I want to propose one more method for memory metrics -
segmentFillVariance, float value from 0.0 to 1.0.
Motivation: when persistence is enabled, we split memory policy into K
equal segments (K = concurrency level). We calculate hash of pageId to
determine segment where page will be stored.
Pages eviction to disk starts when segment is full. If hash function is
bad enough, one segment can overflow when there are lots of free space, and
evictions can start too early. We want to be able to distinguish such
situations.
I propose to calculate segmentFillVariance as difference between maximum
and minimum percentage of segment fill. Greater variance signals about
worse hash function.
Thoughts?
--
Best Regards,
Ivan Rakov
