Date: Fri, 26 Oct 2012 16:31:12 +0000 (UTC) From: Adrian Chadd <adrian@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r242144 - head/sys/dev/ath Message-ID: <201210261631.q9QGVCnF040108@svn.freebsd.org>
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Author: adrian Date: Fri Oct 26 16:31:12 2012 New Revision: 242144 URL: http://svn.freebsd.org/changeset/base/242144 Log: Since it's not immediately obvious whether the current TX path handles fragment rate lookups correctly, add a comment describing exactly that. The assumption in the fragment duration code is the duration of the next fragment will match the rate used by the current fragment. But I think a rate lookup is being done for _each_ fragment. For older pre-sample rate control this would almost always be the case, but for sample it may be incorrect more often then correct. Modified: head/sys/dev/ath/if_ath_tx.c Modified: head/sys/dev/ath/if_ath_tx.c ============================================================================== --- head/sys/dev/ath/if_ath_tx.c Fri Oct 26 16:30:49 2012 (r242143) +++ head/sys/dev/ath/if_ath_tx.c Fri Oct 26 16:31:12 2012 (r242144) @@ -1067,6 +1067,10 @@ ath_tx_calc_duration(struct ath_softc *s * Include the size of next fragment so NAV is * updated properly. The last fragment uses only * the ACK duration + * + * XXX TODO: ensure that the rate lookup for each + * fragment is the same as the rate used by the + * first fragment! */ dur += ath_hal_computetxtime(ah, rt, bf->bf_m->m_nextpkt->m_pkthdr.len,
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