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