Date: Sat, 26 Jun 1999 16:38:57 +0930 (CST) From: "Daniel J. O'Connor" <darius@dons.net.au> To: Jesus Monroy <jesus.monroy@usa.net> Cc: hackers@freebsd.org, Ville-Pertti Keinonen <will@iki.fi> Subject: Re: [Re: coarse vs fine-grained locking in SMP systems] Message-ID: <XFMail.990626163857.darius@dons.net.au> In-Reply-To: <19990626055629.6978.qmail@www0i.netaddress.usa.net>
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This message is in MIME format --_=XFMail.1.3.p0.FreeBSD:990626163857:34751=_ Content-Type: text/plain; charset=us-ascii On 26-Jun-99 Jesus Monroy wrote: > > An approach like that can't possibly be sufficient if code has been > > written with the assumption that only interrupt-like events or > > blocking calls can change things from under it. There is quite a bit > > of code in FreeBSD that relies on this. > Can you elaborate on this a bit more? I think I missing > some of the finer points on what you are saying. > > I work on interrupt driven device drivers and I'm trying > to see how this ties in. The reason is that if kernel code is written to not protect against reentrancy then it will have race conditions in SMP. The splXXX() macros are used in drivers to protect against code reentrancy when an interrupt occurs. Usually they are around routines which modify a data structure which can also be modified by the drivers interrupt handler. --- Daniel O'Connor software and network engineer for Genesis Software - http://www.gsoft.com.au "The nice thing about standards is that there are so many of them to choose from." -- Andrew Tanenbaum --_=XFMail.1.3.p0.FreeBSD:990626163857:34751=_ Content-Type: application/pgp-signature -----BEGIN PGP MESSAGE----- Version: 2.6.3ia iQCVAwUBN3R8iWj0TqzKxF7VAQGKtwQAgkwovC3e9dzHCU22qorxqMUADR4B9Znm ENuUYeO+Y/Ge09UEuRYfisnD5rxK9yPCcswFvKPbYvnG04S/DOjXKIARBI8rYd2G WVlZZ1cZM4CH96TA/yXoPuurLlvtEfRi2qGGICnJo8FaVS9twG/fQbiSDIgLx6PH 8Ed7aulFb1U= =VMZP -----END PGP MESSAGE----- --_=XFMail.1.3.p0.FreeBSD:990626163857:34751=_-- End of MIME message To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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