On Thu, Nov 20 2003, Alan Stern wrote: > On Thu, 20 Nov 2003, Jens Axboe wrote: > > > Well yes, that's what my objection is against - adding that member. Did > > you not read any of my mails? And it's quite simple why - basically > > noone will add it, so it'll end up being 512 anyways. > > All right, fine. Host adapter drivers have the option of setting the > dma_alignment mask in their slave_configure() routines. Doing it there > won't add anything to the host template, will leave the value at its > default 512 for host drivers that don't care, and will let drivers that do > care set it to the optimal value. > > The important thing is that sg and st should check the alignment of the > actual buffer against the dma_alignment mask, which they currently don't > do.
Sure fine. I still don't think it's worth anybodies time messing with. > > I just don't see the point. It's a miniscule optimization. If you need > > that last bit of performance, then align your buffers and noone loses. > > See? > > I'm not sure -- was that "you" directed at me personally or at userspace > program writers in general? Telling me to align the user buffers won't > help anything; it's the program writers who need to be informed of the > restrictions. And it's the host-driver writers who need to loosen those > restrictions where applicable. You as in program writers, clearly you cannot do anything about it. Of course sg/st/whatever cannot pass down badly aligned sg addresses, that's a given. And I think they are currently broken that they don't attempt to align to 512 bytes. I just think we've waisted way more time discussion the issue than what will ever be saved in cpu time. -- Jens Axboe ------------------------------------------------------- This SF.net email is sponsored by: SF.net Giveback Program. Does SourceForge.net help you be more productive? Does it help you create better code? SHARE THE LOVE, and help us help YOU! Click Here: http://sourceforge.net/donate/ _______________________________________________ [EMAIL PROTECTED] To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
