Re: [RFC] [PATCH 0/3] ioat: DMA engine support

From: Jeff Garzik
Date: Wed Nov 23 2005 - 17:06:29 EST

Andrew Grover wrote:
As presented in our talk at this year's OLS, the Bensley platform, which will be out in early 2006, will have an asyncronous DMA engine. It can be used to offload copies from the CPU, such as the kernel copies of received packets into the user buffer.

IOAT is super-neat stuff.

In addition to helping speed up network RX, I would like to see how possible it is to experiment with IOAT uses outside of networking. 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.

Additionally, current IOAT is memory->memory. I would love to be able to convince Intel to add transforms and checksums, to enable offload of memory->transform->memory and memory->checksum->result operations like sha-{1,256} hashing[1], crc32*, aes crypto, and other highly common operations. All of that could be made async.


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