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Date:   Mon, 14 May 2018 13:46:00 +0300
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()
Message-ID: <20180514104600.GC8228@linux.intel.com>
References: <20180507160733.8817-1-nayna@linux.vnet.ibm.com>
 <20180507160733.8817-2-nayna@linux.vnet.ibm.com>
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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