Date: Wed, 22 Mar 1995 03:57:42 -0800 From: David Greenman <davidg@Root.COM> To: Bruce Evans <bde@zeta.org.au> Cc: freebsd-hackers@freefall.cdrom.com, kuku@gilberto.physik.rwth-aachen.de Subject: Re: Why IDE is bad Message-ID: <199503221157.DAA02482@corbin.Root.COM> In-Reply-To: Your message of "Wed, 22 Mar 95 21:49:25 %2B1000." <199503221149.VAA12384@godzilla.zeta.org.au>
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>>>This might explain why my Intr time is so much lower than Poul's. >>>I have only 16MB, and don't use option BOUNCE_BUFFERS. The bcopy() >>>for bouncing is done in a call from biodone(). biodone() is called >>>from the interrupt handler, at least for the wd driver. > >> Bounce buffers are not used on wd-style drives. > >I just looked at wd.c because there's no direct call to biodone() in >bt742a.c. I think it gets called from the upper layers for scsi >drivers. It's called from sd.c and other places. Only B_BOUNCE buffers are freed in biodone. B_BOUNCE buffers are only created in vm_bounce_alloc(), and that is only called for bus mastering controllers that can't DMA above 16MB. -DG
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