Date: Sat, 14 Feb 1998 02:45:57 +0000 (GMT) From: Terry Lambert <tlambert@primenet.com> To: chuckr@glue.umd.edu (Chuck Robey) Cc: julian@whistle.com, current@FreeBSD.ORG Subject: Re: Working (apparently) soft-update code available. Message-ID: <199802140245.TAA12922@usr06.primenet.com> In-Reply-To: <Pine.BSF.3.96.980213202731.4456T-100000@localhost> from "Chuck Robey" at Feb 13, 98 08:27:59 pm
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> > look in: > > ftp://ftp.freebsd.org/pub/FreeBSD/incoming/softupdates4.tgz > > > > first extract the README and read it before extracting everything. > > this should patch cleanly against last night's -current. > > Julian, is this safe for an SMP system? As long as you are using the Big Giant Lock, it should be safe. The syncer process that replaces updated runs as a kernel process; this means that it's a process in the kernel address space and with a seperate stack. In theory, this will prevent you from coming in an doing something while it's doing something. But this theory depends on the Big Giant Lock in the scheduler. A pushdown below the system call trap layer could make this dangerous, unless done exactly right. Heed Julian's warning and run it on an expendable partition. I would be very interested in seeing a three-process thrash on a two processor machine (or an N+1 process thrash on an N processor machine) to see if you can kick it in the groin through the scheduler (SMP FreeBSD does not have CPU affinity in the form of seperate scheduler queues with a roll count for the idle process to determine the right time to do load migration). "We didn't make the Big Giant Lock, we only made it Big and Giant!" -- FreeBSD/SMP Terry Lambert terry@lambert.org --- Any opinions in this posting are my own and not those of my present or previous employers. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message
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