Bug 467328

Summary:	kernel-pae installed even if not needed
Product:	[openSUSE] openSUSE 11.2	Reporter:	Michal Svec <msvec>
Component:	YaST2	Assignee:	Jiri Srain <jsrain>
Status:	RESOLVED FIXED	QA Contact:	Jiri Srain <jsrain>
Severity:	Normal
Priority:	P3 - Medium	CC:	meissner
Version:	unspecified
Target Milestone:	---
Hardware:	Other
OS:	Other
Whiteboard:
Found By:	---	Services Priority:
Business Priority:		Blocker:	---
Marketing QA Status:	---	IT Deployment:	---

Description Michal Svec 2009-01-19 12:38:52 UTC

Currently kernel-pae is installed even on hardware where it does not
bring any advantage, like if has small RAM and does not have nx (but
still cpu flags it supports pae).

It should be installed in these two cases:
  1. /proc/cpuinfo contains pae and host has >4GB of memory
  2. /proc/cpuinfo contains nx

This affects older hw, where the performance gain could be eventually useful.
Cf. also feature 159006.

Comment 1 Jiri Srain 2009-01-19 14:34:19 UTC

Technically wise, I can change the code to behave as described above (just a little correction, >3GB because of I/O devices mapping, or, basicallym revert to the previous behavior and additionally add the nx flag check). However,

Andreas, can you comment on the performance hit caused by PAE? Is it worth the change?

Thorsten, is this something you will still accept for SLE11?

Comment 2 Thorsten Kukuk 2009-01-19 16:12:15 UTC

No, nothing anymore we will accept.

Comment 3 Andreas Gruenbacher 2009-01-19 16:26:24 UTC

> Andreas, can you comment on the performance hit caused by PAE? Is it worth the
> change?

I don't remember; it was somewhere in the low single-digit percentage range. Moving this to 11.2.

Comment 4 Jiri Srain 2009-02-18 14:40:45 UTC

Adjusted the condition in SVN for 11.2.

if ((memsize >= fourGB || contains (cpuflags, "nx")) && contains (cpuflags, "pae"))