Date: Wed, 13 Dec 2000 02:04:40 +1100 (EST) From: Bruce Evans <bde@zeta.org.au> To: John Baldwin <jhb@FreeBSD.org> Cc: cvs-committers@FreeBSD.org, cvs-all@FreeBSD.org Subject: Re: cvs commit: src/sys/kern kern_ktr.c Message-ID: <Pine.BSF.4.21.0012130124150.585-100000@besplex.bde.org> In-Reply-To: <200012120043.eBC0hqx94479@freefall.freebsd.org>
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On Mon, 11 Dec 2000, John Baldwin wrote: > jhb 2000/12/11 16:43:50 PST > > Modified files: > sys/kern kern_ktr.c > Log: > - Don't bother taking a trace message if we have panic'd since doing so > can lead to further panics. > - Call getnanotime() instead of nanotime() for the timestamp. nanotime() > is more precise, but it also calls into the timer code, which results > in mutex operations on the i386 arch. If KTR_LOCK is turned on, then Mutex operations actually resulted only on the i386 arch, only if the i8254 timecounter was used (i.e., mainly on pre-PCI pre-Pentium systems). Both the alpha and the i386 have an i8254 timecounter which should use mutex operations, but the alpha version was copied from the i386 version before mutex operations were added to the latter, and it has rotted. High resolution kernel profiling has similar problems. mcount() and mexitcount() need to be callable from almost anywhere, and they call timer/counter code (cputime()) which needs to use locks for certain timer/cointers (i8254, and maybe performance counters). Things currently sort of work because the necessary locking is missing. Bruce To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe cvs-all" in the body of the message
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