How to properly include long chapter titles into headings?

I am writing a PhD thesis which contains a long chapter title:

\chapter{On the edge of universality of sequential P systems}

When I use standard headings pagestyle:

\pagestyle{headings}

Then the title in the heading overflows and it looks ugly:

When I use fancy pagestyle:

\usepackage{fancyhdr}
\pagestyle{fancy}

It is somewhat better, but it is still pretty unreadable:

I have found another option, to display shorter version of chapter title in the heading (http://ift.tt/16Oxb0I):

\chapter{On the edge of universality of sequential P systems}
\chaptermark{On the edge of universality of seq\dots}

I think, anything is possible. But what is the best practice for these long titles?