Hardcode kernel module info - Revision history

FransMeulenbroeks at 12:41, 16 November 2008

2008-11-16T12:41:43Z

Tim Bird: /* Patch for 2.4.17 kernel */ switch from Image link to Media link

2007-09-18T23:31:01Z

‎Patch for 2.4.17 kernel: switch from Image link to Media link

Tim Bird: /* Patch for 2.4.17 kernel */

2007-09-18T23:28:43Z

‎Patch for 2.4.17 kernel

Tim Bird: create page with info about problem

2007-09-18T23:24:13Z

create page with info about problem

New page

Sony found that with the 2.4 kernel, and an extremely large kernel loadable module, it could take the kernel
module loader up to 3 seconds just to scan the relocation table for the module in order to load it.

The following patch allows one to pass some arguments to the kernel command line to hardcode some
of the information that is detected at module load time. This reduced the module load time significantly
for this situation.

This is a very specialized problem, but in case some one finds this useful, here's a more detailed description
of the problem, and a patch:

== Detailed problem description ==
We've found that <tt>module_frob_arch_sections(ppc)</tt> takes a long time to
find unique symbols in the relocation sections of the kernel module's
elf header.

Our particular kernel module had a relocation section with
13757 entries(2749 unique ones) in it, and for this module,
we measured 3 seconds to process this section by count_reloc
function.

(There may be a way to not generate all this many entries,
or not do the relocations in insmod etc... but we don't know
about it at this time.)

We made a patch to just work around this problem by just passing
the size info by the argument when insmod happens, and not do
actual counting.

-Whether we should think of fixing the count algorithm or other
proper way of fixing this.
-Whether we should think of an option not to do any relocations
at all

== Patch for 2.4.17 kernel ==

← Older revision		Revision as of 12:41, 16 November 2008
Line 36:		Line 36:

	This patch makes it possible to specify the core size and init size, avoiding the call to module_frob_arch_sections()		This patch makes it possible to specify the core size and init size, avoiding the call to module_frob_arch_sections()
		+
		+	[[Category:Boot Time]]
		+	[[Category:Kernel]]

@@ Line 33: / Line 33: @@
 == Patch for 2.4.17 kernel ==
-Download the patch at: [[Image:Elf plt info.patch]]
+Download the patch at: [[Media:Elf plt info.patch|Elf_plt_info.patch]]
 This patch makes it possible to specify the core size and init size, avoiding the call to module_frob_arch_sections()

← Older revision		Revision as of 23:28, 18 September 2007
Line 33:		Line 33:

	== Patch for 2.4.17 kernel ==		== Patch for 2.4.17 kernel ==
		+	Download the patch at: [[Image:Elf plt info.patch]]
		+
		+	This patch makes it possible to specify the core size and init size, avoiding the call to module_frob_arch_sections()