Date: Thu, 23 Dec 1999 14:30:47 -0500 (EST) From: Bill Paul <wpaul@skynet.ctr.columbia.edu> To: dillon@apollo.backplane.com (Matthew Dillon) Cc: julian@whistle.com, scottm@CS.UCLA.EDU, jlemon@americantv.com, brad@shub-internet.org, jabley@patho.gen.nz, phk@critter.freebsd.dk, wollman@khavrinen.lcs.mit.edu, current@freebsd.org Subject: Re: Woa! May have found something - 'rl' driver and small packets (was Re: Odd TCP glitches in new currents) Message-ID: <199912231930.OAA11526@skynet.ctr.columbia.edu> In-Reply-To: <199912230641.WAA16876@apollo.backplane.com> from "Matthew Dillon" at Dec 22, 99 10:41:13 pm
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Okay, I patched if_rl.c in -current to fixe the problem demonstrated by Matt's linktest program. The bug was actually on the receive side of the rl driver, not the transmit side. A packet can wrap from the end of the RX buffer back to the beginning, and in some cases these packets would get lost due to botched use of m_pullup(). I can run the linktest program now without losing any frames. There's another way around this which is to allocate a whole mbuf cluster when you know the packet is wrapped and bcopy the data manually instead of using m_devget(), but I'm not sure I want to waste a whole cluster just for that case. -Bill -- ============================================================================= -Bill Paul (212) 854-6020 | System Manager, Master of Unix-Fu Work: wpaul@ctr.columbia.edu | Center for Telecommunications Research Home: wpaul@skynet.ctr.columbia.edu | Columbia University, New York City ============================================================================= "It is not I who am crazy; it is I who am mad!" - Ren Hoek, "Space Madness" ============================================================================= To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message
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