Is this skb recycle buffer helpful to improve network stack performance?

From: LeoY
Date: Sat Oct 08 2005 - 16:30:30 EST


Motivation: we noticed alloc_skb()/kfree() used lots of clock ticks when handling heavy network traffic. As Linux kernel always need to call kmalloc()/kfree() to allocate and deallocate a skb DATA buffer(not sk_buff) for each incoming/outgoing packet, we try to reduce the frequence of calling these memory functions.

I wangt to set up a ring buffer in Linux kernel(skbuff.c) and recycle those skb data buffers. The basic idea is as follows:
1. Create a ring buffer. This ring buffer has a head pointer which points to the virtual address of the data buffer to be reused; It also has a tail pointer, which can be used to store the virutal address of skb data buffer for those transmitted packets.
2. If the ring buffer is full, just use normal kmalloc()/kfree() operation to manager those skb data buffers instead of recycling them.
3. if any DATA buffer is available, Instead of calling kmalloc(), assign a skb data buffer directly from ring buffer to the incoming packets.
4. If ring buffer still has space, Instead of calling kfree(), store the skb data buffer into the ring buffer.
5. if the head and tail pointer overlap and head pointer is not empty, just stop accpeting more DATA buffer until some DATA buffer is used for the incoming packets.

I tested my method on the latest Linux kernel, it works with the normal traffic; However, the Linux kernel crashed under the heavy network traffic.

Any idea to make this ring bufer work under the heavy network traffic?

Thanks a lot,

Leo Y -
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