Date: Sun, 4 Jun 2017 17:50:46 +0900 From: Tomoaki AOKI <junchoon@dec.sakura.ne.jp> To: freebsd-current@freebsd.org Cc: Hans Petter Selasky <hps@selasky.org> Subject: Re: Time to increase MAXPHYS? Message-ID: <20170604175046.f2a9d0f68ce5abefa7c2ac2a@dec.sakura.ne.jp> In-Reply-To: <15e42fd1-055d-28f6-5e24-1448e16954a9@selasky.org> References: <0100015c6fc1167c-6e139920-60d9-4ce3-9f59-15520276aebb-000000@email.amazonses.com> <972dbd34-b5b3-c363-721e-c6e48806e2cd@elischer.org> <3719c729-9434-3121-cf52-393a4453d0b2@freebsd.org> <CANCZdfrkc1ERKnJr4JzHpePmU%2BrN5JOgAVePCShPHLDCAE19=w@mail.gmail.com> <CANCZdfpD3G8gR=C2_AekM6VeJ6dzKOnP820OOoF1M_eS0MfJ3g@mail.gmail.com> <20170604163948.eb5f74ce2a233b8f204ba671@dec.sakura.ne.jp> <15e42fd1-055d-28f6-5e24-1448e16954a9@selasky.org>
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On Sun, 4 Jun 2017 09:52:36 +0200 Hans Petter Selasky <hps@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@freebsd.org mailing list > https://lists.freebsd.org/mailman/listinfo/freebsd-current > To unsubscribe, send any mail to "freebsd-current-unsubscribe@freebsd.org" > -- Tomoaki AOKI <junchoon@dec.sakura.ne.jp>
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