Distribution:Gentoo
Hardware Environment:P4 Prescott, HT enabled, 2x512MB RAM, ICH6 in AHCI mode, 1x
WD Raptor 740GD

Software Environment:
Problem Description:

i have exactly the same problem over here, posted it already in gentoo's
bugzilla  and forum, seems that a few ppl have related/same troubles with
highmem enabled kernels regarding disc performance. with a highmem enabled
kernel my boot time is ~10mins vs < 1min as compared to a highmem enabeld kernel
booted with flag mem=880MB. app start up times are also in the same magnitude
slower. general cpu /system performance seems unaffected.

bonnie output:

highmem, > 1000MB RAM booted
Seeker 1...Seeker 2...Seeker 3...start 'em...done...done...done...
              -------Sequential Output-------- ---Sequential Input-- --Random--
              -Per Char- --Block--- -Rewrite-- -Per Char- --Block--- --Seeks---
Machine    MB K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU  /sec %CPU
          100   843 99.9 214295 78.5 766914 100.3   731 99.9 2364623 101.6
97878.5 185.9

highmem <= 880MB RAM booted
Seeker 1...Seeker 2...Seeker 3...start 'em...done...done...done...
              -------Sequential Output-------- ---Sequential Input-- --Random--
              -Per Char- --Block--- -Rewrite-- -Per Char- --Block--- --Seeks---
Machine    MB K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU  /sec %CPU
          100 45898 99.7 393189 100.2 894995 94.4 50903 100.0 2453987 100.6
147552.5 184.4

Linux eistee 2.6.12-rc4 #2 SMP. Tried -mm, gentoo-dev-sources, love-sources, i
can always reproduce it.

how comes that this bug report is over a year old and nobody of the devs replied?


Steps to reproduce:
1. install vanilla sources kernel
2. enabled highmem patch (4GB)
3. reboot