From: David Miller <davem@davemloft.net>
To: rdreier@cisco.com
Cc: jeff@garzik.org, shawnxjin@gmail.com, linux-kernel@vger.kernel.org
Subject: Re: Multiple MSI messages support
Date: Tue, 30 Oct 2007 16:02:21 -0700 (PDT) [thread overview]
Message-ID: <20071030.160221.27099706.davem@davemloft.net> (raw)
In-Reply-To: <adaejfci5cz.fsf@cisco.com>
From: Roland Dreier <rdreier@cisco.com>
Date: Tue, 30 Oct 2007 15:51:08 -0700
> In fact at least IBM pSeries boxes seem to be able to use MSI to
> generate multiple interrupts from the same device -- BenH can probably
> give details.
Sparc64 PCI-E controllers can do this as well.
> For high-performance devices this is not really true. The InfiniBand
> mthca driver can use MSI to get a single interrupt, or MSI-X to get
> different interrupts for different types of events. MSI-X allows the
> read of the "interrupt cause register" to be avoided, and this ends up
> making a measurable performance difference for the fast path.
>
> Also, obviously, having multiple interrupts means you can bind
> different interrupts to different CPUs, which will become very
> important if/when things like multi-queue NICs are supported.
Right, and this is used heavily in the NIU driver for example.
next prev parent reply other threads:[~2007-10-30 23:02 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-10-30 21:13 Shawn Jin
2007-10-30 22:23 ` Jeff Garzik
2007-10-30 22:51 ` Roland Dreier
2007-10-30 23:02 ` David Miller [this message]
2007-10-31 1:34 ` Shawn Jin
2007-10-31 4:00 ` Jeff Garzik
2007-10-31 5:05 ` Shawn Jin
2007-10-31 5:17 ` Roland Dreier
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