Re: mapping user space buffer to kernel address space

From: David S. Miller (davem@redhat.com)
Date: Tue Oct 17 2000 - 14:27:30 EST


   Date: Tue, 17 Oct 2000 21:32:43 +0200
   From: Andrea Arcangeli <andrea@suse.de>

> Bye, bye, performance. You might as well remove the whole thing
> completely.

   I don't think that is a common case relevant for performance. I
   seen it only as a case that we must handle without losing
   stability.

Hint: smp_flush_tlb_page()

Current kiobufs never need to do that, under any circumstances.
This is not by accident.

I don't see what the big deal is in requiring that user applications
do their own locking to protect page contents being modified in one
thread while a direct I/O from it is happening in another thread. I
also don't see why any bug with kiobufs can't be fixed without the
expensive and complex pinning.

Later,
David S. Miller
davem@redhat.com
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