From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alan Cox Subject: Re: [RFC] [PATCH 0/3] ioat: DMA engine support Date: Wed, 23 Nov 2005 22:54:04 +0000 Message-ID: <1132786445.13095.32.camel@localhost.localdomain> References: <4384E7F2.2030508@pobox.com> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Cc: Andrew Grover , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, john.ronciak@intel.com, christopher.leech@intel.com Return-path: To: Jeff Garzik In-Reply-To: <4384E7F2.2030508@pobox.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On Mer, 2005-11-23 at 17:06 -0500, Jeff Garzik wrote: > Sample ideas: VM page pre-zeroing. ATA PIO data xfers (async copy to > static buffer, to dramatically shorten length of kmap+irqsave time). > Extremely large memcpy() calls. ATA PIO copies are 512 bytes of memory per sector and that is usually already in cache and on cache line boundaries. You won't even be able to measure it done by the CPU. I can't see the I/O engine sync cost being worth it. Might just about help large transfers I guess but you don't do multisector which is the only case you'd get perhaps 8K an I/O. > Additionally, current IOAT is memory->memory. I would love to be able > to convince Intel to add transforms and checksums, Not just transforms but also masks and maybe even merges and textures would be rather handy 8)