On Fri, Jan 17, 2020 at 8:10 AM Deepak Ukey <deepak.ukey@xxxxxxxxxxxxx> wrote:
>
> From: Peter Chang <dpf@xxxxxxxxxx>
>
> 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@xxxxxxxxxx>
> Signed-off-by: Deepak Ukey <deepak.ukey@xxxxxxxxxxxxx>
> Signed-off-by: Viswas G <Viswas.G@xxxxxxxxxxxxx>
> Signed-off-by: Radha Ramachandran <radha@xxxxxxxxxx>
> Reported-by: kbuild test robot <lkp@xxxxxxxxx>
> ---
> 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?
--- PM8001 driver has a memory limit in the machine. If we increase the sg length, we need to trade-off it by decreasing PM8001_MAX_CCB. PM8001_MAX_CCB = 256 does not have any influence on normal use.
The patch itself looks fine.
