From: Andi Kleen <ak@muc.de>
To: Christoph Lameter <clameter@sgi.com>
Cc: linux-ia64@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: Page Fault Scalability patch V19 [1/4]: pte_cmpxchg and CONFIG_ATOMIC_TABLE_OPS
Date: Thu, 10 Mar 2005 00:01:22 +0100 [thread overview]
Message-ID: <m1y8cwv2yl.fsf@muc.de> (raw)
In-Reply-To: <20050309201329.29721.1860.sendpatchset@schroedinger.engr.sgi.com> (Christoph Lameter's message of "Wed, 9 Mar 2005 12:13:29 -0800 (PST)")
Christoph Lameter <clameter@sgi.com> writes:
>
> Atomic operations may be enabled in the kernel configuration on
> i386, ia64 and x86_64 if a suitable CPU is configured in SMP mode.
> Generic atomic definitions for ptep_xchg and ptep_cmpxchg
> have been provided based on the existing xchg() and cmpxchg() functions
> that already work atomically on many platforms. It is very
I'm curious - do you have any micro benchmarks on i386 or x86-64 systems
about the difference between spin_lock(ptl) access; spin_unlock(ptl);
and cmpxchg ?
cmpxchg can be quite slow, with bad luck it could be slower than
the spinlocks.
A P4 would be good to benchmark this because it seems to be the worst
case.
-Andi
next prev parent reply other threads:[~2005-03-09 23:16 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-03-09 20:13 Page Fault Scalabilty patch V19 [0/4]: Overview Christoph Lameter
2005-03-09 20:13 ` Page Fault Scalability patch V19 [1/4]: pte_cmpxchg and CONFIG_ATOMIC_TABLE_OPS Christoph Lameter
2005-03-09 23:01 ` Andi Kleen [this message]
2005-03-09 23:06 ` Christoph Lameter
2005-03-09 20:13 ` Page Fault Scalability patch V19 [2/4]: Abstract mm_struct counter operations Christoph Lameter
2005-03-09 20:13 ` Page Fault Scalability patch V19 [3/4]: Drop use of page_table_lock in handle_mm_fault Christoph Lameter
2005-03-09 20:13 ` Page Fault Scalability patch V19 [4/4]: Drop use of page_table_lock in do_anonymous_page Christoph Lameter
2005-03-09 22:56 ` Andi Kleen
2005-03-09 23:02 ` Christoph Lameter
2005-03-09 23:14 ` Andi Kleen
2005-03-09 23:17 ` Christoph Lameter
2005-03-09 23:21 ` Andi Kleen
2005-03-09 23:32 ` Christoph Lameter
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