From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mga17.intel.com ([192.55.52.151]:35325 "EHLO mga17.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752113AbeENKqI (ORCPT ); Mon, 14 May 2018 06:46:08 -0400 Date: Mon, 14 May 2018 13:46:00 +0300 From: Jarkko Sakkinen To: Nayna Jain 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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <20180507160733.8817-2-nayna@linux.vnet.ibm.com> Sender: linux-integrity-owner@vger.kernel.org List-ID: 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 Reviewed-by: Jarkko Sakkinen /Jarkko