From: Manfred Spraul <manfred@colorfullife.com>
To: Christoph Lameter <clameter@sgi.com>
Cc: linux-kernel@vger.kernel.org
Subject: Re: page fault fastpath: Increasing SMP scalability by introducing pte
Date: Sun, 15 Aug 2004 16:17:11 +0200 [thread overview]
Message-ID: <411F7067.8040305@colorfullife.com> (raw)
Christoph wrote:
>Well this is more an idea than a real patch yet. The page_table_lock
>becomes a bottleneck if more than 4 CPUs are rapidly allocating and using
>memory. "pft" is a program that measures the performance of page faults on
>SMP system. It allocates memory simultaneously in multiple threads thereby
>causing lots of page faults for anonymous pages.
>
>
>
Very odd. Why do you see a problem with the page_table_lock but no
problem from the mmap semaphore?
The page fault codepath acquires both.
How often is the page table lock acquired per page fault? Just once or
multiple spin_lock calls per page fault? Is the problem contention or
cache line trashing?
Do you have profile/lockmeter output? Is the down_read() in
do_page_fault() a hot spot, too?
--
Manfred
next reply other threads:[~2004-08-15 14:14 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-08-15 14:17 Manfred Spraul [this message]
2004-08-15 15:10 ` page fault fastpath: Increasing SMP scalability by introducing pte William Lee Irwin III
2004-08-15 19:36 ` Christoph Lameter
2004-08-15 20:06 ` Christoph Lameter
2004-08-16 5:23 ` Manfred Spraul
-- strict thread matches above, loose matches on Subject: below --
2004-08-15 13:50 Christoph Lameter
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