linux-kernel - [PATCH v2 0/4] additional TPM performance improvements

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Date:   Wed,  6 Sep 2017 08:56:35 -0400
From:   Nayna Jain <nayna@...ux.vnet.ibm.com>
To:     tpmdd-devel@...ts.sourceforge.net
Cc:     peterhuewe@....de, tpmdd@...horst.net,
        jarkko.sakkinen@...ux.intel.com, jgunthorpe@...idianresearch.com,
        linux-security-module@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        linux-ima-devel@...ts.sourceforge.net, patrickc@...ibm.com,
        Nayna Jain <nayna@...ux.vnet.ibm.com>
Subject: [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