On Sun, 4 Jun 2017 09:52:36 +0200 Hans Petter Selasky <hps_at_selasky.org> wrote: > On 06/04/17 09:39, Tomoaki AOKI wrote: > > Hi > > > > One possibility would be to make it MD build-time OTIONS, > > defaulting 1M on regular systems and 128k on smaller systems. > > > > Of course I guess making it a tunable (or sysctl) would be best, > > though. > > > > Hi, > > A tunable sysctl would be fine, but beware that commonly used firmware > out there produced in the millions might hang in a non-recoverable way > if you exceed their "internal limits". Conditionally lowering this > definition is fine, but increasing it needs to be carefully verified. > > For example many USB devices are only tested with OS'es like Windows and > MacOS and if these have any kind of limitation on the SCSI transfer > sizes, it is very likely many devices out there do not support any > larger transfer sizes either. > > --HPS Hmm, so making it tunable (or sysctl) as Warner noted would allow drivers to use quirks to workaround, i.e., QUIRKS_MAXPHYS_128K. > > _______________________________________________ > freebsd-current_at_freebsd.org mailing list > https://lists.freebsd.org/mailman/listinfo/freebsd-current > To unsubscribe, send any mail to "freebsd-current-unsubscribe_at_freebsd.org" > -- Tomoaki AOKI <junchoon_at_dec.sakura.ne.jp>Received on Sun Jun 04 2017 - 06:50:50 UTC
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