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SubjectRe: [PATCH v2 3/4] tpm: reduce tpm_msleep() time in get_burstcount()
On Wed, Sep 06, 2017 at 08:56:38AM -0400, Nayna Jain wrote:
> Currently, get_burstcount() function sleeps for 5msec in a loop
> before retrying for next query to burstcount. However, if it takes
> lesser time for TPM to return, this 5 msec delay is longer
> than necessary.
>
> This patch replaces the tpm_msleep time from 5msec to 1msec.
>
> After this change, performance on a TPM 1.2 with an 8 byte
> burstcount for 1000 extends improved from ~10sec to ~9sec.
>
> Signed-off-by: Nayna Jain <nayna@linux.vnet.ibm.com>
> Acked-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
> ---
> drivers/char/tpm/tpm_tis_core.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c
> index d1eab29cb447..d710bbc4608b 100644
> --- a/drivers/char/tpm/tpm_tis_core.c
> +++ b/drivers/char/tpm/tpm_tis_core.c
> @@ -169,7 +169,7 @@ static int get_burstcount(struct tpm_chip *chip)
> burstcnt = (value >> 8) & 0xFFFF;
> if (burstcnt)
> return burstcnt;
> - tpm_msleep(TPM_TIMEOUT);
> + tpm_msleep(1);
> } while (time_before(jiffies, stop));
> return -EBUSY;
> }
> --
> 2.13.3

How did you pick 1 ms delay? Should there be a constant defining it?

/Jarkko

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