Date: Thu, 30 Jan 1997 21:21:50 -0500 (EST) From: "John S. Dyson" <toor@dyson.iquest.net> To: joerg_wunsch@uriah.heep.sax.de Cc: freebsd-scsi@freebsd.org Subject: Re: XXXminpys question Message-ID: <199701310221.VAA06077@dyson.iquest.net> In-Reply-To: <Mutt.19970130225620.j@uriah.heep.sax.de> from "J Wunsch" at Jan 30, 97 10:56:20 pm
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> As Peter Dufault wrote: > > > > The adapters _are_ the reason for a minphys, so there should only be > > > one at all. We should probably add it to the cdevsw entries. It can > > > default to minphys (64 KB). > > > > You still want an overall system minphys to prevent a rogue driver / rogue > > dd from crashing the system. It is the maximum amount you're willing to > > guarantee to lock down for a raw transfer. > > I remember that David Greenman once said that the main reason for the > existing minphys was the limitation of the SCSI adapters. > > Maybe there should be another minphys, but more something like 1 MB or > larger then. The existing 64 KB limitation is something seriously > small. > It will require some restructuring of the pbuf (physical I/O buffer) code, but isn't that bad to do. It has been in my queue for a while. If the driver-savvy people can work out a way to query the driver for the maximum I/O size, I can/will implement the upper level changes. John Dyson
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