Re: Slow loading big kernel module in 2.6 on PPC platform

[Wilson Li]

>--- "linux-os (Dick Johnson)" <linux-os@xxxxxxxxxxxx> wrote:
> 
> On Wed, 28 Sep 2005, Wilson Li wrote:
> 
> I have a module I am currently working on. It has some assembly
> stuff linked with it, so it was easy to modify. In the assembly
> I allocated 16 megabytes of static storage (using the .space
> keyword),
> first in the .data section, then in .rodata, then in .text. The
> .text section is where code exists. In no case did the module take
> more than 1/4 second to load. In all cases the size shown by
> `lsmod`
> reflected the enormous size of the module.
> 
> Now, that's static storage. If your code uses kmalloc() and
> friends to allocate a lot of storage when it is being loaded,
> then that's a different story. FYI, when you see a kernel message
> on the screen, that's not necessarily when it was "printed". It
> gets buffered, you know. If you want to time-check when various
> sections get control, to find out what's eating the time, then
> put the jiffie count into your kernel messages.
> 
> A simple macro using the __FUNCTION__ string and the jiffie
> count can go a long way towards finding out what's happening.
> 
> For instance, I once had a problem with continuous interrupts
> from a device, that couldn't be cleared, until the device was
> initialized. That slowed the system to a stand-still until
> I found that. The fix was easy, do some initialization before
> attaching the interrupt, at least enough to quiet the board.
> This board had an empty FPGA, whos bits need to be loaded
> with a bit-banger to make it work. The pin connected to an
> interrupt was just whatever-it-was-from-the-factory, before
> the intelligence was loaded. That system took about a minute
> for the first kernel message to be printed. Sometimes the
> system was very quiet <forever> and needed to be kicked.
> 
> 
> Cheers,
> Dick Johnson
> Penguin : Linux version 2.6.13 on an i686 machine (5589.55
> BogoMips).
> Warning : 98.36% of all statistics are fiction.
> 
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> Thank you.

Appreciate your advice and help. I finally tracked it down to the
function called in init_module() in kernel/module.c.
 
/* Allow arches to frob section contents and sizes.  */
err = module_frob_arch_sections(hdr, sechdrs, secstrings, mod);

which takes most of time (more then 99%) during module loading just
as the reply from Semuel earlier.

Wilson Li
 



		
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