Re: [PATCH V2 01/13] pm80xx : Increase request sg length.

Jinpu Wang
2020-01-17T14:09:10Z

On Fri, Jan 17, 2020 at 8:10 AM Deepak Ukey <deepak.ukey@microchip.com> wrote:
>
> From: Peter Chang <dpf@google.com>
>
> Increasing the per-request size maximum (max_sectors_kb) runs into
> the per-device dma scatter gather list limit (max_segments) for
> users of the io vector system calls (eg, readv and writev). This is
> because the kernel combines io vectors into dma segments when
> possible, but it doesn't work for our user because the vectors in the
> buffer cache get scrambled.
> This change bumps the advertised max scatter gather length to 528 to
> cover 2M w/ x86's 4k pages and some extra for the user checksum.
> It trims the size of some of the tables we don't care about and
> exposes all of the command slots upstream to the scsi layer
>
> Signed-off-by: Peter Chang <dpf@google.com>
> Signed-off-by: Deepak Ukey <deepak.ukey@microchip.com>
> Signed-off-by: Viswas G <Viswas.G@microchip.com>
> Signed-off-by: Radha Ramachandran <radha@google.com>
> Reported-by: kbuild test robot <lkp@intel.com>
> ---
> drivers/scsi/pm8001/pm8001_defs.h | 5 +++--
> drivers/scsi/pm8001/pm8001_init.c | 2 +-
> 2 files changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/scsi/pm8001/pm8001_defs.h b/drivers/scsi/pm8001/pm8001_defs.h
> index 48e0624ecc68..1c7f15fd69ce 100644
> --- a/drivers/scsi/pm8001/pm8001_defs.h
> +++ b/drivers/scsi/pm8001/pm8001_defs.h
> @@ -75,7 +75,7 @@ enum port_type {
> };
>
> /* driver compile-time configuration */
> -#define PM8001_MAX_CCB 512 /* max ccbs supported */
> +#define PM8001_MAX_CCB 256 /* max ccbs supported */
Hi Deepack,

Why do you reduce PM8001_MAX_CCB?

The patch itself looks fine.