Date: Wed, 6 Feb 2002 13:59:57 -0500 From: Garance A Drosihn <drosih@rpi.edu> To: obrien@FreeBSD.org, John Baldwin <jhb@FreeBSD.org> Cc: current@FreeBSD.org Subject: Re: Performance of -current vs -stable Message-ID: <p0510140db88729d2a89c@[128.113.24.47]> In-Reply-To: <20020206091311.A96921@dragon.nuxi.com> References: <p05101401b88638b62611@[128.113.24.47]> <XFMail.020206010234.jhb@FreeBSD.org> <20020206091311.A96921@dragon.nuxi.com>
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At 9:13 AM -0800 2/6/02, David O'Brien wrote: >On Wed, Feb 06, 2002 at 01:02:34AM -0500, John Baldwin wrote: >> WITNESS can really hurt. Quite possibly I should turn it off in >> GENERIC now (I wouldn't mind if someone else did that.) > >I think it should stay. Especially as we are not getting much usage in >-CURRENT. If we turn it off by default, it should come back on 3 mo. >before 5.0-RELEASE for testing. (and yes off for the actual release). I was thinking that maybe it should stay in the GENERIC kernel, along with some comment that indicates how much of a performance hit will be seen if it's on. "This is desirable for in-depth debugging, but it does mean that system calls will take three times longer than if the option is off". It's good to have the extra checking, but we don't want to scare people away from running current simply because they think it will take three times longer to get anything done on current. (or maybe even comment the option out, but do leave the line there along with the statement that "we'd appreciate it if people would run with this option on, even though it will cause a noticeable slowdown."). I do think it's important that we (developers) spend more time on current, but I think the way I'll do it is to compile two kernels, one with the WITNESS and one without it. For much of what I do I can absorb the extra overhead of WITNESS code, but a three-hour buildworld will throw my entire "buildworld schedule" off, and I just won't be able to rebuild the system as often. -- Garance Alistair Drosehn = gad@eclipse.acs.rpi.edu Senior Systems Programmer or gad@freebsd.org Rensselaer Polytechnic Institute or drosih@rpi.edu To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message
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