Bug 529660

Summary:	sys-apps/portage: performance optimization: memoize use_reduce results for _slot_operator_update_probe
Product:	Portage Development	Reporter:	Zac Medico <zmedico>
Component:	Core - Dependencies	Assignee:	Portage team <dev-portage>
Status:	RESOLVED FIXED
Severity:	enhancement	CC:	bircoph, pacho
Priority:	Normal	Keywords:	InVCS
Version:	2.2
Hardware:	All
OS:	All
URL:	http://thread.gmane.org/gmane.linux.gentoo.devel/93603/focus=93816
See Also:	https://bugs.gentoo.org/show_bug.cgi?id=732378
Whiteboard:
Package list:		Runtime testing required:	---
Bug Depends on:
Bug Blocks:	155723, 835380

Description Zac Medico gentoo-dev

2014-11-18 06:41:23 UTC

Profiling has shown that depgraph._slot_operator_update_probe is repeating the same use_reduce calls for the same package. I have a patch which implements memoization of use_reduce results for this function, and it significantly improves performance of dependency calculations. With memoization, 'emerge -puvDN @world' on one of my computers takes 22.4% less time, and results in 13.5% fewer use_reduce calls.

Comment 1 Zac Medico gentoo-dev

2014-11-18 06:59:49 UTC

My patch is in the following branch:

	https://github.com/zmedico/portage/tree/bug_529660

I've posted it for review here:

	http://thread.gmane.org/gmane.linux.gentoo.portage.devel/4814

Comment 2 Zac Medico gentoo-dev

2014-11-24 08:23:15 UTC

This is in the master branch:

https://github.com/gentoo/portage/commit/9ba4f2aa6a2755a73fb652b4557919047d649fd1

Comment 3 Andrew Savchenko gentoo-dev

2014-12-04 10:39:09 UTC

Apparently this patch is in 2.2.15.
Thanks!