X86 (32-Bit) Red Hat Legacy Information; Bigmem/Hugemem And Up Systems; Performance Implications - HP xw3400 User Manual

x86 (32-bit) Red Hat Legacy Information

Bigmem Kernel is used on Red Hat 7.2, 7.3, 8.0 and 9
Hugemem Kernel is used on Red Hat Enterprise 3 and later
Starting with Red Hat Enterprise Linux WS 3, the i686 SMP kernel is sufficient for the maximum
amount of memory, up to 16GB, in HP Workstations. With greater then 16GB large memory
configurations, the kernel hugemem is recommended. With 4GB and greater memory configurations,
if the "Enable Memory Remapping" option is enabled in the BIOS, you will have access to all your
memory.
In order for earlier Linux operating systems to use more than 3.5GB of physical memory, a special
kernel called the bigmem kernel must be used. For example, for kernel 2.4.18-26, the rpm package
that provides that kernel for Red Hat 8.0 is kernel-bigmem-2.4.18-26.8.x.i686.rpm. If more than
3.5GB of memory is installed and a bigmem kernel is not used, the system can only use 3.5GB of the
memory.
The bigmem kernel rpm installs like most Red Hat Linux rpms:
rpm –i kernel-bigmem-2.4.18-26.8.x.i686.rpm
You need to reinstall accelerated HP graphics drivers from the HP Linux Installer Kit CDs, or the latest
driver from
http://www.hp.com/go/workstationsupport
work correctly, you must install the source for the particular version of the kernel you installed. Install
the kernel source before you attempt to reinstall the graphics driver. The kernel source should be
available from wherever you got the bigmem kernel rpm.
To reinstall the graphics driver:
Identify the accelerated driver that was installed on the UP kernel.
1.
rpm ñqa |grep nv
rpm ñqa |grep firegl
Remove the driver that was identified.
2.
rpm ñe <name from output of previous step>
Install the new driver.
3.
rpm ñi <driver name>.rpm
Run the configure script.
4.
cd /usr/hp/graphics/<vendor name> for Legacy Red Hat versions or,
cd /opt/hp/graphics/<vendor name> for Red Hat Enterprise Linux
./configure
You might also need to rebuild and/or reinstall any other loadable kernel modules on your system
because a different module is needed for each different Linux kernel.

Bigmem/Hugemem and UP systems

The bigmem/hugemem kernel as released by Red Hat is an SMP (Symetric Multi-Processing) kernel,
which means that it can support multiple CPUs. The bigmem/hugemem kernel has only been tested by
HP on dual CPU systems and on single CPU systems with Hyper-Threading Technology enabled, plus
4GB or more of memory. Thus, using the bigmem/hugemem kernel on systems with one virtual CPU
or less than 4GB of memory is not supported.

Performance Implications

When using the bigmem/hugemem kernel, memory references inside the kernel require one more
level of indirection, so general system performance might suffer slightly compared to using the SMP or
. In order for the accelerated graphics driver to
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