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Re: [PATCH 2/6] dma: bcm-sba-raid: Peek mbox when we are left with no free requests

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On Thu, Jul 27, 2017 at 10:25:25AM +0530, Anup Patel wrote:
> On Wed, Jul 26, 2017 at 10:40 PM, Vinod Koul <vinod.koul@intel.com> wrote:
> > On Wed, Jul 26, 2017 at 11:06:40AM +0530, Anup Patel wrote:
> >> We should peek mbox channels when we are left with no free
> >> sba_requests in sba_alloc_request()
> >
> > and why is the world should we do that, how does that help??
> 
> When setting up RAID array on several NVMe disk we observed
> that sba_alloc_request() start failing (due to no free requests left)
> and RAID array setup becomes very slow.
> 
> Doing mbox channel peek when we have no free requests left,
> improves performance of RAID array setup.

How about documenting this tribal knowledge in the changelog. Changelogs are
very useful, 6 months down the line, you will struggle to remember why this
was changed..

> 
> This change is inspired from mv_chan_alloc_slot() implemented
> in drivers/dma/mv_xor.c
> 
> Regards,
> Anup

-- 
~Vinod

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[PATCH 0/6] Broadcom SBA-RAID driver improvements Anup Patel <anup.patel@broadcom.com> - 2017-07-26 07:40 +0200
  [PATCH 1/6] dma: bcm-sba-raid: Improve memory allocation in SBA RAID driver Anup Patel <anup.patel@broadcom.com> - 2017-07-26 07:40 +0200
    Re: [PATCH 1/6] dma: bcm-sba-raid: Improve memory allocation in SBA  RAID driver Vinod Koul <vinod.koul@intel.com> - 2017-07-26 19:10 +0200
      Re: [PATCH 1/6] dma: bcm-sba-raid: Improve memory allocation in SBA  RAID driver Anup Patel <anup.patel@broadcom.com> - 2017-07-27 06:20 +0200
        Re: [PATCH 1/6] dma: bcm-sba-raid: Improve memory allocation in SBA  RAID driver Vinod Koul <vinod.koul@intel.com> - 2017-07-28 05:20 +0200
          Re: [PATCH 1/6] dma: bcm-sba-raid: Improve memory allocation in SBA  RAID driver Anup Patel <anup.patel@broadcom.com> - 2017-07-28 05:50 +0200
  [PATCH 2/6] dma: bcm-sba-raid: Peek mbox when we are left with no free requests Anup Patel <anup.patel@broadcom.com> - 2017-07-26 07:40 +0200
    Re: [PATCH 2/6] dma: bcm-sba-raid: Peek mbox when we are left with  no free requests Vinod Koul <vinod.koul@intel.com> - 2017-07-26 19:10 +0200
      Re: [PATCH 2/6] dma: bcm-sba-raid: Peek mbox when we are left with no  free requests Anup Patel <anup.patel@broadcom.com> - 2017-07-27 07:00 +0200
        Re: [PATCH 2/6] dma: bcm-sba-raid: Peek mbox when we are left with  no free requests Vinod Koul <vinod.koul@intel.com> - 2017-07-28 05:20 +0200
          Re: [PATCH 2/6] dma: bcm-sba-raid: Peek mbox when we are left with no  free requests Anup Patel <anup.patel@broadcom.com> - 2017-07-28 05:40 +0200
  [PATCH 6/6] arm64: dts: Add SBA-RAID DT nodes for Stingray SoC Anup Patel <anup.patel@broadcom.com> - 2017-07-26 07:40 +0200
  Re: [PATCH 0/6] Broadcom SBA-RAID driver improvements Vinod Koul <vinod.koul@intel.com> - 2017-07-26 19:10 +0200
    Re: [PATCH 0/6] Broadcom SBA-RAID driver improvements Anup Patel <anup.patel@broadcom.com> - 2017-07-27 06:10 +0200

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