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From: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
To: Nayna Jain <nayna@linux.vnet.ibm.com>
Cc: linux-integrity@vger.kernel.org, zohar@linux.vnet.ibm.com,
	linux-security-module@vger.kernel.org,
	linux-kernel@vger.kernel.org, peterhuewe@gmx.de,
	tpmdd@selhorst.net, jgunthorpe@obsidianresearch.com,
	patrickc@us.ibm.com
Subject: Re: [PATCH v3 1/2] tpm: reduce poll sleep time in tpm_transmit()
Date: Mon, 14 May 2018 13:46:00 +0300	[thread overview]
Message-ID: <20180514104600.GC8228@linux.intel.com> (raw)
In-Reply-To: <20180507160733.8817-2-nayna@linux.vnet.ibm.com>

On Mon, May 07, 2018 at 12:07:32PM -0400, Nayna Jain wrote:
> tpm_try_transmit currently checks TPM status every 5 msecs between
> send and recv. It does so in a loop for the maximum timeout as defined
> in the TPM Interface Specification. However, the TPM may return before
> 5 msecs. Thus the polling interval for each iteration can be reduced,
> which improves overall performance. This patch changes the polling sleep
> time from 5 msecs to 1 msec.
> 
> Additionally, this patch renames TPM_POLL_SLEEP to TPM_TIMEOUT_POLL and
> moves it to tpm.h as an enum value.
> 
> After this change, performance on a system[1] with a TPM 1.2 with an 8 byte
> burstcount for 1000 extends improved from ~14 sec to ~10.7 sec.
> 
> [1] All tests are performed on an x86 based, locked down, single purpose
> closed system. It has Infineon TPM 1.2 using LPC Bus.
> 
> Signed-off-by: Nayna Jain <nayna@linux.vnet.ibm.com>
 
Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>

/Jarkko

  parent reply	other threads:[~2018-05-14 10:46 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-05-07 16:07 [PATCH v3 0/2] tpm: improving granularity in poll sleep times Nayna Jain
2018-05-07 16:07 ` [PATCH v3 1/2] tpm: reduce poll sleep time in tpm_transmit() Nayna Jain
2018-05-08 16:34   ` J Freyensee
2018-05-10 12:41     ` Nayna Jain
2018-05-14 10:39       ` Nayna Jain
2018-05-14 10:46   ` Jarkko Sakkinen [this message]
2018-05-14 10:47     ` Jarkko Sakkinen
2018-05-07 16:07 ` [PATCH v3 2/2] tpm: reduce polling time to usecs for even finer granularity Nayna Jain
2018-05-08 16:34   ` J Freyensee
2018-05-14 10:52   ` Jarkko Sakkinen

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