From: Nayna Jain <nayna@linux.vnet.ibm.com>
To: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.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 4/5] tpm: reduce tpm_msleep() time in get_burstcount()
Date: Thu, 12 Oct 2017 18:44:13 +0530 [thread overview]
Message-ID: <945e7428-62a8-27e8-beca-99f14a11d210@linux.vnet.ibm.com> (raw)
In-Reply-To: <20171012111835.g7uulven4whnpf5d@linux.intel.com>
On 10/12/2017 04:48 PM, Jarkko Sakkinen wrote:
> On Wed, Oct 04, 2017 at 06:29:23AM -0400, Nayna Jain wrote:
>> 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
>>
> Would it make sense to squash this to 3/5 and merge the commit
> messages?
Yeah.. it sounds reasonable.. both are reducing the sleep delay time for
same purpose, just in different functions.
Thanks & Regards,
- Nayna
>
> /Jarkko
>
next prev parent reply other threads:[~2017-10-12 13:14 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 ` [PATCH v3 4/5] tpm: reduce tpm_msleep() time in get_burstcount() Nayna Jain
2017-10-12 11:18 ` Jarkko Sakkinen
2017-10-12 13:14 ` Nayna Jain [this message]
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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