On Wed, Nov 27, 2002 at 11:56:33AM -0800, Julian Elischer wrote: > On Wed, 27 Nov 2002, Robert Watson wrote: > > I'd like to continue to explore options for reducing the number of memory > > allocations to extend storage on mbufs. One idea I've been tossing around > > is adopting Jeff Roberson's extension model used in struct proc and > > related structures. > > I've been wondering about a couple of things.. > 1/ soemtiems I wonder if ALL mbufs should not be external mbufs. > > In other words, if the mbuf were always just a header and data was > always stored on an external buffer it might actually simplify some > code. It would then become possible that some tag space > be allocated along with the mbuf header.. if MAC was > in the system, then every mbuf would be allocated with a MAC tag by > default. Maybe as a single allocation. The UMA allocator's init() > capability gives us a lot of latitude in doing things like that.
I don't see how that would simplify anything. You would still need two allocations for external storage because you need to offer third-party code the possibility to provide its own external storage type (think jumbo bufs or sendfile(2) or the zero-copy code). You don't really gain anything except for maybe potential space wastage for very small packets by "always allocating an mbuf with external storage" (you may only save a really quick and negligeable size comparison, but that's it). As for non-third-party type external storage (your standard 2K mbuf clusters) those can be allocated in one shot with an mbuf pre-attached to it by the existing allocator anyway and an interface is provided to do so (m_getcl(), iirc). -- Bosko Milekic * [EMAIL PROTECTED] * [EMAIL PROTECTED] To Unsubscribe: send mail to [EMAIL PROTECTED] with "unsubscribe freebsd-current" in the body of the message
