From: Jesse Barnes <jesse.barnes@intel.com>
To: hadi@cyberus.ca
Cc: Arthur Kepner <akepner@sgi.com>,
Lennert Buytenhek <buytenh@wantstofly.org>,
netdev@oss.sgi.com, gnb@sgi.com
Subject: Re: [PATCH] use mmiowb in tg3_poll
Date: Tue, 31 May 2005 09:45:36 -0700 [thread overview]
Message-ID: <200505310945.36903.jesse.barnes@intel.com> (raw)
In-Reply-To: <1117544022.6134.54.camel@localhost.localdomain>
On Tuesday, May 31, 2005 5:53 am, jamal wrote:
> Did i read correctly that your reads are about 2x more expensive than
> the writes?
The test above just measures the difference between using a full PIO
read to ensure write ordering vs. the lighter weight mmiowb call. As
for your question though, non-relaxed reads are very expensive on the
Altix platform due to its highly distributed NUMA I/O architecture.
The _relaxed variants can be quite fast however, and can be used
anytime a PIO read doesn't imply anything about previous DMA
transactions.
Jesse
prev parent reply other threads:[~2005-05-31 16:45 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <200410211613.19601.jbarnes@engr.sgi.com>
2004-10-21 23:28 ` [PATCH] use mmiowb in tg3.c Jesse Barnes
2004-10-21 23:40 ` David S. Miller
2004-10-22 1:16 ` Benjamin Herrenschmidt
2004-10-22 1:33 ` akepner
2004-10-22 2:07 ` Benjamin Herrenschmidt
2004-10-22 3:01 ` Jesse Barnes
2004-10-22 4:00 ` Paul Mackerras
2004-10-22 20:51 ` [PATCH] use mmiowb in tg3_poll akepner
2005-05-28 23:12 ` Lennert Buytenhek
2005-05-30 16:30 ` Arthur Kepner
2005-05-31 12:53 ` jamal
2005-05-31 16:45 ` Jesse Barnes [this message]
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