Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1576688

Re: [PATCH v2 2/5] async_tx: Handle DMA devices having support for fewer PQ coefficients

Show all headers | View raw

On Wed, Feb 8, 2017 at 12:57 AM, Anup Patel <anup.patel@broadcom.com> wrote:
> On Tue, Feb 7, 2017 at 11:46 PM, Dan Williams <dan.j.williams@intel.com> wrote:
>> On Tue, Feb 7, 2017 at 1:02 AM, Anup Patel <anup.patel@broadcom.com> wrote:
>>> On Tue, Feb 7, 2017 at 1:57 PM, Dan Williams <dan.j.williams@intel.com> wrote:
>>>> On Tue, Feb 7, 2017 at 12:16 AM, Anup Patel <anup.patel@broadcom.com> wrote:
>>>>> The DMAENGINE framework assumes that if PQ offload is supported by a
>>>>> DMA device then all 256 PQ coefficients are supported. This assumption
>>>>> does not hold anymore because we now have BCM-SBA-RAID offload engine
>>>>> which supports PQ offload with limited number of PQ coefficients.
>>>>>
>>>>> This patch extends async_tx APIs to handle DMA devices with support
>>>>> for fewer PQ coefficients.
>>>>>
>>>>> Signed-off-by: Anup Patel <anup.patel@broadcom.com>
>>>>> Reviewed-by: Scott Branden <scott.branden@broadcom.com>
>>>>
>>>> I don't like this approach. Define an interface for md to query the
>>>> offload engine once at the beginning of time. We should not be adding
>>>> any new extensions to async_tx.
>>>
>>> Even if we do capability checks in Linux MD, we still need a way
>>> for DMAENGINE drivers to advertise number of PQ coefficients
>>> handled by the HW.
>>>
>>> I agree capability checks should be done once in Linux MD but I don't
>>> see why this has to be part of BCM-SBA-RAID driver patches. We need
>>> separate patchsets to address limitations of async_tx framework.
>>
>> Right, separate enabling before we pile on new hardware support to a
>> known broken framework.
>
> Linux Async Tx not broken framework. The issue is:
> 1. Its not complete enough
> 2. Its not optimized for very high through-put offload engines

I'm not understanding your point. I'm nak'ing this change to add yet
more per-transaction capability checking to async_tx. I don't like the
DMA_HAS_FEWER_PQ_COEF flag, especially since it is equal to
DMA_HAS_PQ_CONTINUE. I'm not asking for all of async_tx's problems to
be fixed before this new hardware support, I'm simply saying we should
start the process of moving offload-engine capability checking to the
raid code.

Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

[PATCH v2 0/5] Broadcom SBA RAID support Anup Patel <anup.patel@broadcom.com> - 2017-02-07 09:20 +0100
  [PATCH v2 3/5] async_tx: Fix DMA_PREP_FENCE usage in do_async_gen_syndrome() Anup Patel <anup.patel@broadcom.com> - 2017-02-07 09:20 +0100
  [PATCH v2 2/5] async_tx: Handle DMA devices having support for fewer PQ coefficients Anup Patel <anup.patel@broadcom.com> - 2017-02-07 09:20 +0100
    Re: [PATCH v2 2/5] async_tx: Handle DMA devices having support for  fewer PQ coefficients Dan Williams <dan.j.williams@intel.com> - 2017-02-07 09:30 +0100
      Re: [PATCH v2 2/5] async_tx: Handle DMA devices having support for  fewer PQ coefficients Anup Patel <anup.patel@broadcom.com> - 2017-02-07 10:20 +0100
        Re: [PATCH v2 2/5] async_tx: Handle DMA devices having support for  fewer PQ coefficients Vinod Koul <vinod.koul@intel.com> - 2017-02-07 17:50 +0100
          Re: [PATCH v2 2/5] async_tx: Handle DMA devices having support for  fewer PQ coefficients Anup Patel <anup.patel@broadcom.com> - 2017-02-08 07:40 +0100
        Re: [PATCH v2 2/5] async_tx: Handle DMA devices having support for  fewer PQ coefficients Dan Williams <dan.j.williams@intel.com> - 2017-02-07 19:20 +0100
          Re: [PATCH v2 2/5] async_tx: Handle DMA devices having support for  fewer PQ coefficients Anup Patel <anup.patel@broadcom.com> - 2017-02-08 10:00 +0100
            Re: [PATCH v2 2/5] async_tx: Handle DMA devices having support for  fewer PQ coefficients Dan Williams <dan.j.williams@intel.com> - 2017-02-08 17:30 +0100
              Re: [PATCH v2 2/5] async_tx: Handle DMA devices having support for  fewer PQ coefficients Anup Patel <anup.patel@broadcom.com> - 2017-02-09 10:40 +0100
                Re: [PATCH v2 2/5] async_tx: Handle DMA devices having support for  fewer PQ coefficients Dan Williams <dan.j.williams@intel.com> - 2017-02-09 17:50 +0100
                Re: [PATCH v2 2/5] async_tx: Handle DMA devices having support for  fewer PQ coefficients Anup Patel <anup.patel@broadcom.com> - 2017-02-10 04:30 +0100
  [PATCH v2 1/5] lib/raid6: Add log-of-2 table for RAID6 HW requiring disk position Anup Patel <anup.patel@broadcom.com> - 2017-02-07 09:20 +0100
  [PATCH v2 5/5] dt-bindings: Add DT bindings document for Broadcom SBA RAID driver Anup Patel <anup.patel@broadcom.com> - 2017-02-07 09:20 +0100

csiph-web