Date: Mon, 5 Feb 2001 18:02:04 -0800 (PST) From: Tom Samplonius <tom@sdf.com> To: "Kenneth D. Merry" <ken@kdm.org> Cc: Mike Smith <msmith@FreeBSD.ORG>, freebsd-scsi@FreeBSD.ORG Subject: Re: Tags and the mly driver Message-ID: <Pine.BSF.4.05.10102051754190.21039-100000@misery.sdf.com> In-Reply-To: <20010205152804.A85729@panzer.kdm.org>
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On Mon, 5 Feb 2001, Kenneth D. Merry wrote: ... > I don't know what that message is about, but from what I can see, we should > only be sending one command to that device at a time, and there shouldn't > be any way we could send any more, since the device doesn't claim to > support tagged queueing. > > So, in short, it doesn't look like your problem is related to trying to > increase the tags, since I don't think you can. Well, that it isn't too good. That would mean CAM is serializing all IO to the mly driver, right? That would be a likely reason why the mlx based cards are faster than the mly based cards, as the mlx driver does not go through the CAM layer. In practice, cards using the mly based cards are quite a bit slower than mlx cards, even though mly based cards all have faster processors, more cache, faster SCSI channels, and 64bit PCI. > To verify this, try: > > camcontrol tags da0 -N 4 -v ... > > Then you can't do tagged queueing and the settings aren't having any > effect. If dev_openings + dev_active are greater than 1, we've got a > problem, since we shouldn't be allowing that to happen for a device that > doesn't claim to support tagged queueing. "camcontrol tags da0 -N 4" increases the number openings. I can even see that actually working a bit, as dev_active is > 1 when repeatedly checking with camcontrol. However, shortly there after, the mly driver hangs. ... > Yeah, camcontrol bails if the get transfer settings CCB fails, although > you'll still see 'Tagged Queueing Enabled' in the dmesg if the array > actually supports it. It really isn't what the array supports, but the driver, isn't it? The dpt driver presents a single virtualized SCSI disk to the CAM layer. > My guess is that the DPT driver reports queue full until we've reduced the > number of tags to 2, thus the reason you get two. > > 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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