session: allow small pacer bursts

session: allow small pacer bursts

Instead of enforcing a "strict" release of data, which relies on
frequent rescheduling of sessions, allow some pacer coalescing, i.e.,
short bursts, that can minimize load on scheduler/session layer and
potentially leverage tso.

Type: improvement

Signed-off-by: Florin Coras <fcoras@cisco.com>
Change-Id: I67e38e5b8dc335bd214113b70c68c27ae92bd6da