On 10/17/2014 02:11 AM, David Laight wrote:
From: Alexander Duyck
...
Actually the likelihood of anything holding onto the 4K page for very
long doesn't seem to occur, at least from the drivers perspective. It
is one of the reasons why I went for the page reuse approach rather than
just partitioning a single large page. It allows us to avoid having to
call IOMMU map/unmap for the pages since the entire page is usually back
in the driver ownership before we need to reuse the portion given to the
stack.
That is almost certainly true for most benchmarks, benchmark processes
consume receive data.
But what about real life situations?
There must be some 'normal' workloads where receive data doesn't get consumed.
David
Yes, but for workloads where receive data doesn't get consumed it is
very unlikely that much receive data is generated. As such from the
device perspective the time the socket is holding the page is still not
all that long as the descriptor ring is not being looped through that
quickly. The page has almost always been freed by the time we have
processed our way through the full descriptor ring.
Thanks,
Alex
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