Intel manual Buffer Management, Intel IXP400 Software Buffer Flow

Intel® IXP400 Software

Buffer Management

Figure 3. Intel® IXP400 Software Buffer Flow

OS	Access-layer Components	AQM	NPE
	Allocate
OS buffer	IXP_BUF	RxFree Q	Update
	buffer
Receive			IXP_BUF
		Rx Q	:ixp_ne
			structure
Driver	Translation
	OSBUF<->IXP_BUF
Transmit		Tx Q	Update
OS buffer	Free IXP_BUF		IXP_BUF
	buffer		:ixp_ne
		TxDone Q
			structure
ix_ctrl: Pool management	IX_MBUF: OS specific	ix_ne: shared structure gets
fields gets updated	structure gets updated		updated
			B-3824

The access-layer component may call a client-registered callback function to return the buffer, or may put the buffer back on a free queue for the client to poll. The access-layer components utilize similar buffer management techniques when communicating with the NPEs.

The network data buffers and their formats (as well as management of the buffers), must be ‘familiar’ to all components so that the buffers can efficiently flow in the system. The IXP400 software uses two internal buffer formats for all network data:

•IXP_BUF

•raw buffer

These two formats are compatible with the IXP400 software’s access-layer components and NPEs.

IXP_BUF

The IXP_BUF is the Intel® IXP400 Software defined buffer format used by the access-layer components. As shown in Figure 4, the Operating System Abstraction Layer of Intel® IXP400 Software v2.0 provides the users with macros to read and write the IX_OSAL_MBUF fields of the IXP_BUF buffer. The Intel® IXP400 Software v2.0 users are expected to use the IX_MBUF_xxx macros provided with the API to access the IX_OSAL_MBUF fields.

April 2005	IXP400 Software Version 2.0	Programmer’s Guide
36	Document Number: 252539, Revision: 007