Very Computer

by **Perry W** » Tue, 19 Oct 2004 18:44:29

Hi all,

I have a strange problem describes as follows:

I have wrote a network device driver and
tried to test its performance by using Smartbit.

The driver performance is 18 Mbps when I use "insmod driver.o".
But it is 22 Mbps when I use this driver as "built-in kernel driver".

Why the performance result between "Module" and "Kernel" is different?

Does this result reasonable?

I need your suggestions. Thank you!

Regards,
Perry.

by **Stephen Hemminge** » Fri, 22 Oct 2004 14:17:33

> Hi all,

> I have a strange problem describes as follows:

> I have wrote a network device driver and
> tried to test its performance by using Smartbit.

> The driver performance is 18 Mbps when I use "insmod driver.o".
> But it is 22 Mbps when I use this driver as "built-in kernel driver".

> Why the performance result between "Module" and "Kernel" is different?

> Does this result reasonable?

> I need your suggestions. Thank you!

It can happen because module reference's end up a different TLB and
get called through an indirect linkage. Sort of the same overhead
as DLL or COM.

Driver performace "Kernel Mode" and "Module Mode"?