<rcpilot2010@gmail.com> wrote:
I have my implementation of socket APIs,
I sock_unregister(AF_INET); & sock_register(&inet_family_ops), this replaces kernel resident socket related calls with my socket related calls. My code is loaded as kernel module.
My question, is Linux kernel able to call its own socket call more efficiently (less overhead, fewer CPU cycles) than mine ? code is running on Intel x86_64 arch.
Any pointer is appreciated.
IMHO, strictly from module vs core kernel code perspective, there is no speed difference.
The reason is, once the kernel is loaded, it is the kernel itself. So it is not separated into isolated segment or something like that. Yes module is loaded into vmalloc-ed memory area, but that's it.
Is it possible that since my code of socket API is located in different part of memory, so that it needs to make a long jump (results in d-cache miss) ?
here is statistics: from per stats tool:
Linux code: 112,880,163,053 instructions:HG # 0.72 insns per cycle
My code: 32,074,097,170 instructions:HG # 0.34 insns per cycle
Hi...
please Cc: to kernelnewbies as well.
Sorry about this, I thought I did.
as for d-cache miss, I think that's not due to long jump, but accessing something not cache aligned.
You mean cache aligned or alignment of address to 4 or 8 bytes ? even data alignment have much effect of the performance on Intel ?
Or maybe you can think something that can be pref etched. That way, you utilize the processor pipeline better, but use it wisely
How about TLB misses, as I understand main kernel is stored in permanently mapped area while module is stored in dynamically mapped area