yongari 2006-08-14 01:50:54 UTC
FreeBSD src repository
Modified files:
sys/dev/em if_em.c if_em.h
Log:
Overhaul Rx path to recover from mbuf cluster allocation failure.
o Create one more spare DMA map for Rx handler to recover from
bus_dmamap_load_mbuf_sg(9) failure.
o Make sure to update status bit in Rx descriptors even if we failed
to allocate a new buffer. Previously it resulted in stuck condition
and em_handle_rxtx task took up all available CPU cycles.
o Don't blindly unload DMA map. Reuse loaded DMA map if received
packet has errors. This would speed up Rx processing a bit under
heavy load as it does not need to reload DMA map in case of error.
(bus_dmamap_load_mbuf_sg(9) is the most expensive call in driver
context.)
o Update if_iqdrops counter if it can't allocate a mbuf cluster.
With this change it's now possible to see queue dropped packets
with netstat(1).
o Update mbuf_cluster_failed counter if fixup code failed to
allocate mbuf header.
o Return ENOBUFS instead of ENOMEM in case of Rx fixup failure.
o Make adapter->lmp NULL in case of Rx fixup failure. Strictly
specking it's not necessary for correct operation but it makes
the intention clear.
o Remove now unused dropped_pkts member in softc.
With these changes em(4) should survive mbuf cluster allocation
failure on Rx path.
Reviewed by: pdeuskar, glebius (with improvements)
Revision Changes Path
1.129 +68 -47 src/sys/dev/em/if_em.c
1.48 +1 -1 src/sys/dev/em/if_em.h
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