tree 048db8e12c2b31ec2b88c3154da4c6a77b80028c
parent 329f7dba5f7dc3bc9a30ad00cf373d2e83115aa1
author Alan Hourihane <alanh@fairlite.demon.co.uk> 1131348934 -0800
committer Dave Jones <davej@redhat.com> 1131486234 -0800

[PATCH] AGP performance fixes

AGP allocation/deallocation is suffering major performance issues due to
the nature of global_flush_tlb() being called on every change_page_attr()
call.

For small allocations this isn't really seen, but when you start allocating
50000 pages of AGP space, for say, texture memory, then things can take
seconds to complete.

In some cases the situation is doubled or even quadrupled in the time due
to SMP, or a deallocation, then a new reallocation.  I've had a case of
upto 20 seconds wait time to deallocate and reallocate AGP space.

This patch fixes the problem by making it the caller's responsibility to
call global_flush_tlb(), and so removes it from every instance of mapping a
page into AGP space until the time that all change_page_attr() changes are
done.

Signed-off-by: Dave Jones <davej@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>