Andrew Gallatin wrote:
Garrett D'Amore wrote:
*) For tx, just keep the addresses in low space for now. There
should be enough space to find a few hundred MB of VA space for
packet buffers under the 4GB limit. I don't think we need to support
gigabytes of these after all. When the pool is exhausted, the system
could internally resort to bcopy.
So we cripple performance on good NICs to help crippled NICs?
That's just so backwards. How about we only use the pool and
resort to bcopy if the NIC cannot do 64-bit DMA?
I'd be OK with that... if there was a nice way to represent it.
(Perhaps a "mblk_get_restricted_paddr()" or some such that does the copy
if the mblk needs it.)
If we use the 32-bit pool, then in the common case all NICs will get
good performance. Exhaustion of the pool should ideally be a rare
enough event that it can be slowpathed in either case, without a
significant impact on performance.
-- Garrett
Drew
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