Date: Wed, 6 Feb 2013 08:36:55 -0500 From: John Baldwin <jhb@freebsd.org> To: freebsd-hackers@freebsd.org Cc: Axel Fischer <afischer@marvell.com>, Lino Sanfilippo <lsanfil@marvell.com>, Markus Althoff <malthoff@marvell.com> Subject: Re: Mbuf memory handling Message-ID: <201302060836.55404.jhb@freebsd.org> In-Reply-To: <175CCF5F49938B4D99B2E3EF7F558EBE1C73F401F3@SC-VEXCH4.marvell.com> References: <175CCF5F49938B4D99B2E3EF7F558EBE1C73F401F3@SC-VEXCH4.marvell.com>
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On Wednesday, February 06, 2013 4:50:39 am Lino Sanfilippo wrote: > > Hi all, > > I want to implement a device driver for a NIC which stores received data into chunks within > a page (>=4k) in host memory. One page shall be used for multiple packets and freed > after all mbufs linked to that page have been processed. So I would like to know what is the recommended way > to handle this in FreeBSD? Any hints are very appreciated. I think you can get what you want by allocating M_JUMBOP mbuf clusters for your receive buffers. When you want to split out a packet, allocate a new packet header mbuf and use m_split() to let it take over the rest of the 4k buffer and pass the original mbuf up to if_input() as the new packet. The new mbufs you attach to the cluster via m_split() will all hold a reference on the backing cluster and it won't be freed until all the mbufs are freed. -- John Baldwin
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