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From: Nayna Jain <nayna@linux.vnet.ibm.com>
To: linux-integrity@vger.kernel.org
Cc: zohar@linux.vnet.ibm.com, linux-security-module@vger.kernel.org,
	linux-kernel@vger.kernel.org, peterhuewe@gmx.de,
	jarkko.sakkinen@linux.intel.com, tpmdd@selhorst.net,
	jgunthorpe@obsidianresearch.com, patrickc@us.ibm.com,
	Nayna Jain <nayna@linux.vnet.ibm.com>
Subject: [PATCH v3 4/5] tpm: reduce tpm_msleep() time in get_burstcount()
Date: Wed,  4 Oct 2017 06:29:23 -0400	[thread overview]
Message-ID: <20171004102924.12355-5-nayna@linux.vnet.ibm.com> (raw)
In-Reply-To: <20171004102924.12355-1-nayna@linux.vnet.ibm.com>

Currently, get_burstcount() function sleeps for 5msec in a loop
before retrying for next query to burstcount. However, if it takes
lesser time for TPM to return, this 5msec delay is longer
than necessary.

This patch replaces the tpm_msleep time from 5msec to 1msec.

After this change, performance on a TPM 1.2 with an 8 byte
burstcount for 1000 extends improved from ~10sec to ~9sec.

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

diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c
index 224842e06105..826a0b9c9201 100644
--- a/drivers/char/tpm/tpm_tis_core.c
+++ b/drivers/char/tpm/tpm_tis_core.c
@@ -226,7 +226,7 @@ static int get_burstcount(struct tpm_chip *chip)
 		burstcnt = (value >> 8) & 0xFFFF;
 		if (burstcnt)
 			return burstcnt;
-		tpm_msleep(TPM_TIMEOUT);
+		tpm_msleep(TPM_POLL_SLEEP);
 	} while (time_before(jiffies, stop));
 	return -EBUSY;
 }
-- 
2.13.3

  parent reply	other threads:[~2017-10-04 10:30 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-10-04 10:29 [PATCH v3 0/4] additional TPM performance improvements Nayna Jain
2017-10-04 10:29 ` [PATCH v3 1/5] tpm: move wait_for_tpm_stat() to respective driver files Nayna Jain
2017-10-10 14:57   ` Jarkko Sakkinen
2017-10-04 10:29 ` [PATCH v3 2/5] tpm: ignore burstcount to improve tpm_tis send() performance Nayna Jain
2017-10-10 15:04   ` Jarkko Sakkinen
2017-10-11 11:29     ` Nayna Jain
2017-10-04 10:29 ` [PATCH v3 3/5] tpm: reduce polling delay in tpm_tis wait_for_tpm_stat() Nayna Jain
2017-10-12 11:17   ` Jarkko Sakkinen
2017-10-04 10:29 ` Nayna Jain [this message]
2017-10-12 11:18   ` [PATCH v3 4/5] tpm: reduce tpm_msleep() time in get_burstcount() Jarkko Sakkinen
2017-10-12 13:14     ` Nayna Jain
2017-10-04 10:29 ` [PATCH v3 5/5] tpm: use tpm_msleep() value as max delay Nayna Jain
2017-10-12 11:19   ` Jarkko Sakkinen

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