Re: [PATCH] z3fold: use per-cpu unbuddied lists

From: Andrew Morton
Date: Wed Aug 02 2017 - 19:07:20 EST

On Wed, 2 Aug 2017 12:25:05 +0200 Vitaly Wool <vitalywool@xxxxxxxxx> wrote:

> z3fold is operating on unbuddied lists in a simple manner: in fact,
> it only takes the first entry off the list on a hot path. So if the
> z3fold pool is big enough and balanced well enough, considering
> only the lists local to the current CPU won't be an issue in any
> way, while random I/O performance will go up.

Has the performance benefit been measured? It's a large patch.

> This patch also introduces two worker threads which: one for async
> in-page object layout optimization and one for releasing freed
> pages.

Why? What are the runtime effects of this change? Does this turn
currently-synchronous operations into now-async operations? If so,
what are the implications of this if, say, the workqueue doesn't get
serviced for a while?

etc. Sorry, but I'm not seeing anywhere near enough information and
testing results to justify merging such a large and intrusive patch.