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[PATCH v2 0/4] additional TPM performance improvements

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  [PATCH v2 0/4] additional TPM performance improvements  Nayna Jain <nayna@linux.vnet.ibm.com> - 2017-09-06 15:10 +0200
    [PATCH v2 4/4] tpm: use tpm_msleep() value as max delay Nayna Jain <nayna@linux.vnet.ibm.com> - 2017-09-06 15:10 +0200
    Re: [PATCH v2 0/4] additional TPM performance improvements Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> - 2017-09-07 18:20 +0200

#1727435 — [PATCH v2 0/4] additional TPM performance improvements

After further discussions with the Device Driver working group (ddwg),
the following changes were made: 

* Check for burstcount at least once to confirm the TPM is ready to accept
the data. Similarly, query for the TPM Expect status as sanity check at
the end.

* Make the sleep for status check during send() in the loop less than
5msec.

* Make the sleep in the loop while querying for burstcount less than
5msec.

Below is the list of patches along with the performance improvements
seen with a TPM 1.2 with an 8 byte burstcount for 1000 extends: 

Patch                                        |Improvement(time in sec)

tpm: ignore burstcount to improve tpm_tis    | ~41 - ~14
send() performance.

tpm: define __wait_for_tpm_stat to specify   | ~14 - ~10
variable polling sleep time

tpm: reduce tpm_msleep() time in             | ~10 - ~9
get_burstcount()

tpm: modify tpm_msleep() function to have    | ~9 - ~8
max range

Changelog v2:

* Add module parameter to handle ignoring of burst count during
tpm tis send() operation.
* Add improvements over sleep time to reduce delays.

Nayna Jain (4):
  tpm: ignore burstcount to improve tpm_tis send() performance.
  tpm: define __wait_for_tpm_stat to specify variable polling sleep time
  tpm: reduce tpm_msleep() time in get_burstcount()
  tpm: use tpm_msleep() value as max delay

 Documentation/admin-guide/kernel-parameters.txt |  8 ++++++
 drivers/char/tpm/tpm-interface.c                | 15 ++++++++--
 drivers/char/tpm/tpm.h                          |  7 +++--
 drivers/char/tpm/tpm_tis_core.c                 | 37 +++++++++++++++++++------
 4 files changed, 53 insertions(+), 14 deletions(-)

-- 
2.13.3

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#1727441 — [PATCH v2 4/4] tpm: use tpm_msleep() value as max delay

Currently, tpm_msleep() uses delay_msec as the minimum value in
usleep_range. However, that is the maximum time we want to wait.
The function is modified to use the delay_msec as the maximum
value, not the minimum value.

After this change, performance on a TPM 1.2 with an 8 byte
burstcount for 1000 extends improved from ~9sec to ~8sec.

Signed-off-by: Nayna Jain <nayna@linux.vnet.ibm.com>
Acked-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
---
 drivers/char/tpm/tpm.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h
index eb2f8818eded..ff5a8b7b80b9 100644
--- a/drivers/char/tpm/tpm.h
+++ b/drivers/char/tpm/tpm.h
@@ -533,8 +533,8 @@ int wait_for_tpm_stat(struct tpm_chip *chip, u8 mask, unsigned long timeout,
 
 static inline void tpm_msleep(unsigned int delay_msec)
 {
-	usleep_range(delay_msec * 1000,
-		     (delay_msec * 1000) + TPM_TIMEOUT_RANGE_US);
+	usleep_range((delay_msec * 1000) - TPM_TIMEOUT_RANGE_US,
+		     delay_msec * 1000);
 };
 
 struct tpm_chip *tpm_chip_find_get(int chip_num);
-- 
2.13.3

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#1728288

On Wed, Sep 06, 2017 at 08:56:35AM -0400, Nayna Jain wrote:
> After further discussions with the Device Driver working group (ddwg),
> the following changes were made: 
> 
> * Check for burstcount at least once to confirm the TPM is ready to accept
> the data. Similarly, query for the TPM Expect status as sanity check at
> the end.
> 
> * Make the sleep for status check during send() in the loop less than
> 5msec.
> 
> * Make the sleep in the loop while querying for burstcount less than
> 5msec.
> 
> Below is the list of patches along with the performance improvements
> seen with a TPM 1.2 with an 8 byte burstcount for 1000 extends: 
> 
> Patch                                        |Improvement(time in sec)
> 
> tpm: ignore burstcount to improve tpm_tis    | ~41 - ~14
> send() performance.
> 
> tpm: define __wait_for_tpm_stat to specify   | ~14 - ~10
> variable polling sleep time
> 
> tpm: reduce tpm_msleep() time in             | ~10 - ~9
> get_burstcount()
> 
> tpm: modify tpm_msleep() function to have    | ~9 - ~8
> max range
> 
> Changelog v2:
> 
> * Add module parameter to handle ignoring of burst count during
> tpm tis send() operation.
> * Add improvements over sleep time to reduce delays.
> 
> Nayna Jain (4):
>   tpm: ignore burstcount to improve tpm_tis send() performance.
>   tpm: define __wait_for_tpm_stat to specify variable polling sleep time
>   tpm: reduce tpm_msleep() time in get_burstcount()
>   tpm: use tpm_msleep() value as max delay
> 
>  Documentation/admin-guide/kernel-parameters.txt |  8 ++++++
>  drivers/char/tpm/tpm-interface.c                | 15 ++++++++--
>  drivers/char/tpm/tpm.h                          |  7 +++--
>  drivers/char/tpm/tpm_tis_core.c                 | 37 +++++++++++++++++++------
>  4 files changed, 53 insertions(+), 14 deletions(-)
> 
> -- 
> 2.13.3
> 

I'll look into this after next week.

/Jarkko

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