linux-kernel - Re: [PATCH 06/13] async_tx: add support for asynchronous GF multiplication

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Message-ID: <49C425F5.8060309@intel.com>
Date:	Fri, 20 Mar 2009 16:25:41 -0700
From:	"H. Peter Anvin" <h.peter.anvin@...el.com>
To:	Ilya Yanok <yanok@...raft.com>
CC:	"H. Peter Anvin" <hpa@...or.com>,
	"Williams, Dan J" <dan.j.williams@...el.com>,
	"linux-raid@...r.kernel.org" <linux-raid@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"neilb@...e.de" <neilb@...e.de>,
	"Sosnowski, Maciej" <maciej.sosnowski@...el.com>,
	Yuri Tikhonov <yur@...raft.com>
Subject: Re: [PATCH 06/13] async_tx: add support for asynchronous GF 	multiplication

Ilya Yanok wrote:
>>>
>> That doesn't explain what you expect the code to do.  It still doesn't
>> make sense to me.
> 
> We defined async_pq() function as hardware can do GF multiplication of
> arbitrary elements and we want to take advantage of this fact. But by
> the design of ASYNC_TX API we have to provide synchronous version of
> that function too.
> 

I don't think that makes sense since the algorithm doesn't use 
vector-vector multiplications and there is no need for them.  As such, 
you're actively excluding support for hardware which only provides 
scalar-vector multiplication, even though that is all we need.

In fact, vectorizing the constant doesn't make much sense.

	-hpa

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