[Bug 54635] slow overall performance (because of highmem support and/or AGP settings?)

Michael Tinsay tinsami1 at yahoo.com
Mon Nov 6 10:08:52 UTC 2006


Public bug reported:


I have a P4 1GB system.  Part of the memory is shared with the built-in AGP card.  The BIOS is setup to have a 32MB AGP Aperture.

Problem:  When the Memory Allocated to the AGP Card is 16MB (lower than
the aperture setting)  Ubuntu is very sluggish, like it takes 5 whole
minutes to boot up.  But:

(1)  When the shared memory is at 32MB, Ubuntu is very fast -- 30 seconds from boot to KDM login screen.
(2)  When shared memory is at 16MB and kernel parameter mem=992M is used, Ubuntu is fast. But when mem=1008M is used, performance goes back to "snail" mode.
(3) When using latest available Dapper kernel source (Package Linux-Source-2.6.15), compiled without highmem support, performance is fast.

And:

(1) Problem not encountered with Windows XP (with 32MB aperture and 16MB shared memory)
(2) Problem have been tested to latest available kernels from Breezy, Dapper, and even, Edgy.


Not really a big problem, but should this behavior, once confirmed, should be documented somewhere.  There's a lot of people complaining about slow performance in ubuntuforums.org, this may be one of the culprit.

** Affects: linux-source-2.6.15 (Ubuntu)
     Importance: Undecided
         Status: Unconfirmed

-- 
slow overall performance (because of highmem support and/or AGP settings?)
https://launchpad.net/bugs/54635




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