Date: Mon, 23 Sep 2002 15:34:07 -0600 From: "Kenneth D. Merry" <ken@kdm.org> To: Brooks Davis <brooks@one-eyed-alien.net> Cc: Matthew Jacob <mjacob@feral.com>, scsi@FreeBSD.ORG Subject: Re: cvs commit: src/sys/cam/scsi scsi_all.c Message-ID: <20020923153407.A38651@panzer.kdm.org> In-Reply-To: <20020923141931.A20487@Odin.AC.HMC.Edu>; from brooks@one-eyed-alien.net on Mon, Sep 23, 2002 at 02:19:31PM -0700 References: <20020923134731.A14701@Odin.AC.HMC.Edu> <Pine.BSF.4.21.0209231355210.637-100000@beppo> <20020923141931.A20487@Odin.AC.HMC.Edu>
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On Mon, Sep 23, 2002 at 14:19:31 -0700, Brooks Davis wrote: > On Mon, Sep 23, 2002 at 01:59:48PM -0700, Matthew Jacob wrote: > > > > But you did, in fact, change the default behaviour in that SCSI_DELAY=0 > > had been an accepted config option before. I've restored the ability to > > do this. And I am in no way shooting myself in the foot- that claim on > > your part is unnecessary and misplaced. In a system with 144 PCI slots, > > e.g,, should we ever install FreeBSD on an alpha 8400 and fill it full > > of either Fibre Channel cards, or with SCSI cards that are connected to > > anything more modern than 1992 and more pricey than a UMASS device, I'd > > like to have it finish booting this year. > > > > I don't think it's particularly important to be able use the tunable to > > set back down to zero as long as those of us who need to make the > > behaviour more acceptable for high end system can do so. > > When I looked at the code again, I realized there is one reason to want > to be able to set it to zero which is that the check is now applied to > boot time (in init_scsi_delay()) so is you set SCSI_DELAY=0 you get > SCSI_DELAY=SCSI_MIN_DELAY even if if you compile it in. Given you > example above, maybe we should just remove the checks entierly since in > the current configuration you would have 14.4sec of delay (not hugh, but > perhaps undesirably large). > > My comment about footshooting was refering to removing the attempt to > keep people from trying to set the value in seconds, not that you were > doing it to yourself. I'm fully aware you know more about scsi them > I'm, ever likely to. :) I think we should leave the restriction in place for now. It's far more likely that someone will think that SCSI_DELAY is set in seconds, and set it to something between 0 and 100, which can cause problems on parallel SCSI busses. Keep in mind that the delay is not serialized, it is applied to all busses in parallel. If you set SCSI_DELAY to 15000, you get 15 seconds of delay, no matter how many busses are in the system. Ken -- Kenneth Merry ken@kdm.org To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-scsi" in the body of the message
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