From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeff Garzik Subject: Re: [PATCH 10/11][TG3]: Reduce spurious interrupts. Date: Fri, 04 May 2007 20:42:43 -0400 Message-ID: <463BD303.7000500@garzik.org> References: <1178326521.4859.26.camel@dell> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: davem@davemloft.net, netdev@vger.kernel.org To: Michael Chan Return-path: Received: from srv5.dvmed.net ([207.36.208.214]:53284 "EHLO mail.dvmed.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1423710AbXEEAmq (ORCPT ); Fri, 4 May 2007 20:42:46 -0400 In-Reply-To: <1178326521.4859.26.camel@dell> Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org Michael Chan wrote: > [TG3]: Reduce spurious interrupts. > > Spurious interrupts are often encountered especially on systems > using the 8259 PIC mode. This is because the I/O write to deassert > the interrupt is posted and won't get to the chip immediately. As > a result, the IRQ may remain asserted after the IRQ handler exits, > causing spurious interrupts. > > An unconditional read to flush the I/O write to force the IRQ to de- > assert immediately is not desirable because it impacts performance in > the fast path. So we only do this after we have some indications of > spurious interrupts. > > Signed-off-by: Michael Chan hmmmm, this is a bit questionable that it needs to be here. I think it's just a fact of life that it is important to flush certain writes... I'm not sure a driver needs to be adding code to avoid the obvious solution. It would be annoying if all drivers had code to do this. Jeff