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 v2 1/2] tpm: reduce poll sleep time in tpm_transmit()
Date: Tue, 24 Apr 2018 19:27:52 +0300 [thread overview]
Message-ID: <20180424162752.GC5119@linux.intel.com> (raw)
In-Reply-To: <20180417131246.434-2-nayna@linux.vnet.ibm.com>
On Tue, Apr 17, 2018 at 09:12:45AM -0400, Nayna Jain wrote:
> The TPM polling code in tpm_transmit sleeps in each loop iteration for
> 5 msecs. However, the TPM might return earlier, and thus waiting for
> 5 msecs adds an unnecessary delay. This patch reduces the polling sleep
> time in tpm_transmit() from 5 msecs to 1 msecs.
I'm not sure what TPM returning earlier has to do with this. TPM probably
never returns exactly in the spec defined timeout/duration. I just don't
understand reasoning in this paragraph.
> Additionally, this patch renames TPM_POLL_SLEEP and moves it to tpm.h as
> an enum value.
>
> After this change, performance on a TPM 1.2 with an 8 byte burstcount
> for 1000 extends improved from ~14 sec to ~10.7 sec.
You cannot give absolute numbers without a context (platform, software).
> Signed-off-by: Nayna Jain <nayna@linux.vnet.ibm.com>
/Jarkko
WARNING: multiple messages have this Message-ID (diff)
From: jarkko.sakkinen@linux.intel.com (Jarkko Sakkinen)
To: linux-security-module@vger.kernel.org
Subject: [PATCH v2 1/2] tpm: reduce poll sleep time in tpm_transmit()
Date: Tue, 24 Apr 2018 19:27:52 +0300 [thread overview]
Message-ID: <20180424162752.GC5119@linux.intel.com> (raw)
In-Reply-To: <20180417131246.434-2-nayna@linux.vnet.ibm.com>
On Tue, Apr 17, 2018 at 09:12:45AM -0400, Nayna Jain wrote:
> The TPM polling code in tpm_transmit sleeps in each loop iteration for
> 5 msecs. However, the TPM might return earlier, and thus waiting for
> 5 msecs adds an unnecessary delay. This patch reduces the polling sleep
> time in tpm_transmit() from 5 msecs to 1 msecs.
I'm not sure what TPM returning earlier has to do with this. TPM probably
never returns exactly in the spec defined timeout/duration. I just don't
understand reasoning in this paragraph.
> Additionally, this patch renames TPM_POLL_SLEEP and moves it to tpm.h as
> an enum value.
>
> After this change, performance on a TPM 1.2 with an 8 byte burstcount
> for 1000 extends improved from ~14 sec to ~10.7 sec.
You cannot give absolute numbers without a context (platform, software).
> Signed-off-by: Nayna Jain <nayna@linux.vnet.ibm.com>
/Jarkko
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next prev parent reply other threads:[~2018-04-24 16:27 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-04-17 13:12 [PATCH v2 0/2] tpm: improving granularity in poll sleep times Nayna Jain
2018-04-17 13:12 ` Nayna Jain
2018-04-17 13:12 ` [PATCH v2 1/2] tpm: reduce poll sleep time in tpm_transmit() Nayna Jain
2018-04-17 13:12 ` Nayna Jain
2018-04-18 15:01 ` Mimi Zohar
2018-04-18 15:01 ` Mimi Zohar
2018-04-24 16:27 ` Jarkko Sakkinen [this message]
2018-04-24 16:27 ` Jarkko Sakkinen
2018-04-17 13:12 ` [PATCH v2 2/2] tpm: reduce polling time to usecs for even finer granularity Nayna Jain
2018-04-17 13:12 ` Nayna Jain
2018-04-18 15:02 ` Mimi Zohar
2018-04-18 15:02 ` Mimi Zohar
2018-04-24 16:30 ` Jarkko Sakkinen
2018-04-24 16:30 ` Jarkko Sakkinen
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