svn commit: r336612 - head/sys/net
Marius Strobl
marius at FreeBSD.org
Sun Jul 22 17:51:12 UTC 2018
Author: marius
Date: Sun Jul 22 17:51:11 2018
New Revision: 336612
URL: https://svnweb.freebsd.org/changeset/base/336612
Log:
Use the maximum of isc_tx_{nsegments,tso_segments_max} for MAX_TX_DESC.
Since r336313, TSO support for LEM-class devices is removed again as it
was before the conversion of {l,}em(4) to iflib(4) in r311849 and as a
result, isc_tx_tso_segments_max is 0 for LEM-class devices now. Thus,
inappropriate watermarks were used for this class.
This is really only a band-aid, though, because so far iflib(9) doesn't
fully take into account that DMA engines can support different maxima
of segments for transfers of TSO and non-TSO packets. For example, the
DESC_RECLAIMABLE macro is based on isc_tx_nsegments while MAX_TX_DESC
used isc_tx_tso_segments_max only. For most in-tree consumers that
doesn't make a difference as the maxima are the same for both kinds of
transfers (that is, apart from the fact that TSO may require up to 2
sentinel descriptors but also not with every MAC supported). However,
isc_tx_nsegments is 8 but isc_tx_tso_segments_max is 85 by default
with ixl(4).
Modified:
head/sys/net/iflib.c
Modified: head/sys/net/iflib.c
==============================================================================
--- head/sys/net/iflib.c Sun Jul 22 17:45:44 2018 (r336611)
+++ head/sys/net/iflib.c Sun Jul 22 17:51:11 2018 (r336612)
@@ -2831,7 +2831,8 @@ txq_max_rs_deferred(iflib_txq_t txq)
/* XXX we should be setting this to something other than zero */
#define RECLAIM_THRESH(ctx) ((ctx)->ifc_sctx->isc_tx_reclaim_thresh)
-#define MAX_TX_DESC(ctx) ((ctx)->ifc_softc_ctx.isc_tx_tso_segments_max)
+#define MAX_TX_DESC(ctx) max((ctx)->ifc_softc_ctx.isc_tx_tso_segments_max, \
+ (ctx)->ifc_softc_ctx.isc_tx_nsegments)
static inline bool
iflib_txd_db_check(if_ctx_t ctx, iflib_txq_t txq, int ring, qidx_t in_use)
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