Re: [PATCHv5 0/8] zswap: compressed swap caching

[Seth Jennings <sjenning@linux.vnet.ibm.com>]

On 02/15/2013 09:20 PM, Ric Mason wrote:
> On 02/14/2013 02:38 AM, Seth Jennings wrote:
<snip>
>>
>> Some addition performance metrics regarding the performance
>> improvements and I/O reductions that can be achieved using zswap as
>> measured by SPECjbb are provided here:
>>
>> http://ibm.co/VCgHvM
> 
> I see this link.  You mentioned that "When a user enables zswap and
> the hardware accelerator, zswap simply passes the pages to be
> compressed or decompressed off to the accelerator instead of
> performing the work in software". Then how can user enable hardware
> accelerator, there are option in UEFI or ... ?

zswap uses the cryptographic API for accessing compressor modules.  In
the case of Power7+, we have a crypto API driver (crypto/842.c) which
wraps calls to the real driver (drivers/crypto/nx/nx-842.c) which
makes the hardware calls.

To use a compressor module, use the zswap.compressor attribute on the
kernel parameter.  For P7+, for exmaple:

zswap.compressor=842

> 
>> These results include runs on x86 and new results on Power7+ with
>> hardware compression acceleration.

Thanks,
Seth

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