Date: Sun, 22 Jul 2018 17:51:11 +0000 (UTC) From: Marius Strobl <marius@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r336612 - head/sys/net Message-ID: <201807221751.w6MHpBfa081673@repo.freebsd.org>
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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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