To:     Paul Menzel <pmenzel@molgen.mpg.de>
cc:     linux-raid@vger.kernel.org, LKML <linux-kernel@vger.kernel.org>,
        linux-accelerators@lists.ozlabs.org, linux-nvme@lists.infradead.org
From:   Wolfgang Denk <wd@denx.de>
Subject: Re: Using aGPU for RAID calculations (proprietary GRAID SupremeRAID)
MIME-Version: 1.0
Content-type: text/plain; charset=UTF-8
Content-transfer-encoding: 8bit
In-reply-to: <ccdbb0d7-d043-d41f-508b-4a464ffa5fe9@molgen.mpg.de>
References: <ccdbb0d7-d043-d41f-508b-4a464ffa5fe9@molgen.mpg.de>
Comments: In-reply-to Paul Menzel <pmenzel@molgen.mpg.de>
   message dated "Tue, 30 Nov 2021 12:58:10 +0100."
Date:   Tue, 30 Nov 2021 15:46:25 +0100
Message-ID: <3846571.1638283585@gemini.denx.de>
Precedence: bulk

Dear Paul,

In message <ccdbb0d7-d043-d41f-508b-4a464ffa5fe9@molgen.mpg.de> you wrote:
> 
> I read about GRAID SupremeRAID [1], which seems to be an Nvidia T1000 
> card and software to use the card for RAID calculations.

I doubt this is an efficient way.

The (IMHO) most efficient solution I have seen so far was the AMCC
PPC440SPe Power Architecture processors.  These we able to calculate
the needed parity information on the fly in the DMA controller while
writing the data to disk.

> Does the Linux kernel already have an API to offload calculations to 
> accelerator cards, so it’s basically plug and play (with AMD graphics 
> cards for example using HSA/KFD)? Entropy sources, like the ChaosKey 
> [3], work like that. If not, would the implementation go under `lib/raid6`?

We implemented Linux driver support for adma/async_tx/raid6 for this
hardware, but that was a long time ago (2008/2009), and I doubt this
has been tested recently.  But at least some code is still in
mainline, see for example arch/powerpc/platforms/44x/ppc440spe_dma_engines.c


Best regards,

Wolfgang Denk

-- 
DENX Software Engineering GmbH,      Managing Director: Wolfgang Denk
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd@denx.de
Another megabytes the dust.