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SubjectRe: Multithreaded TCP/IP stack
Brian Hall wrote:
>
> On 13-Jul-2000 Andi Kleen wrote:
> > The 2.2 stack is under two independent locks (kernel lock and bh lock).
> > In later 2.2 the expensive parts of the TX path (copy
> > and checksum) run outside the kernel lock. About half of Incoming runs
> > in the serialized NETBH, but you can save a lot of that by using
> > a NIC that that supports hardware checksumming like the Tornado.
>
> Is this the 3Com 990 series? Is there Linux support for the hardware
> checksumming?

3c590, 3c900, 3c905, 3c575 - they all have hardware support for Tx and
Rx checksums - UDP and TCP. Many other NICs do as well.

Linux uses the hardware checksum on receive, but not on transmit. The
cost of doing the Tx checksum is small compared to the cost of the
mem->mem copy, which is performed at the same time.

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