Re: [PATCH 8/9] scsi: megaraid_sas - Driver take some workloadsfrom FW

[James Bottomley]

On Fri, 2010-11-19 at 10:43 -0700, Yang, Bo wrote:
> Driver added the new feature to take some of the workloads from FW to increase
> performance of the iMR controller.  FW assigns the read cmds back to driver
> which will increase the performance for megaraid sas iMR controller.

Just on a process note: you don't have to cc me at every known
address ... I do read linux-scsi ...

My first take on this patch is that you're basically passing data back
to the kernel for RAID-N parity calculations.  This effectively makes
your RAID one of those pseudo HW ones.  In which case, why not simply
abandon the HW raid piece and have it all done by DM/MD, which are well
optimised for all types of RAID?  The reason for asking is that we're
trying to reduce the number of in-kernel raid implementations and this
is going in the wrong direction.

James


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