Date: Fri, 11 Jan 2002 19:49:04 -0800 From: Peter Wemm <peter@wemm.org> To: Mark Murray <mark@grondar.za> Cc: Chris Faulhaber <jedgar@fxp.org>, scottl@FreeBSD.ORG, smp@FreeBSD.ORG Subject: Re: P5 vs. SMP, part 2 Message-ID: <20020112034904.7784A38FD@overcee.netplex.com.au> In-Reply-To: <200201112015.g0BKFE103071@grimreaper.grondar.org>
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Mark Murray wrote: > > I wonder how many dual P5's are still being used :/ > > I have one (2xP5 @200MHz); I use it only in desktop mode, and it > launches X and Mozilla-CURRENT very slowly. I'm running CURRENT. The good news is that I found part of the problem. Fix: Index: machdep.c =================================================================== RCS file: /home/ncvs/src/sys/i386/i386/machdep.c,v retrieving revision 1.385.2.21 diff -u -1 -2 -r1.385.2.21 machdep.c --- machdep.c 2001/12/13 19:18:00 1.385.2.21 +++ machdep.c 2002/01/12 03:35:12 @@ -1093,24 +1093,25 @@ void cpu_setregs(void) { unsigned int cr0; cr0 = rcr0(); cr0 |= CR0_NE; /* Done by npxinit() */ cr0 |= CR0_MP | CR0_TS; /* Done at every execve() too. */ #ifdef I386_CPU if (cpu_class != CPUCLASS_386) #endif cr0 |= CR0_WP | CR0_AM; + cr0 &= ~(CR0_CD | CR0_NW); load_cr0(cr0); load_gs(_udatasel); } static int sysctl_machdep_adjkerntz(SYSCTL_HANDLER_ARGS) { int error; error = sysctl_handle_int(oidp, oidp->oid_arg1, oidp->oid_arg2, req); if (!error && req->newptr) resettodr(); The problem is that the AP cpus were running with the CR0_CD (cache disable) and CR0_NW (cache writethrough, not writeback). This is very bad. :-] PPro and above bioses seem to cause the AP cpus enter the kernel with cache enabled, so that this looks like it should be a p5/i586 problem only. Cheers, -Peter -- Peter Wemm - peter@FreeBSD.org; peter@yahoo-inc.com; peter@netplex.com.au "All of this is for nothing if we don't go to the stars" - JMS/B5 To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-smp" in the body of the message
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