[PATCH 2/3] tpm: reduce poll sleep time between send() and recv() in tpm_transmit()
zohar at linux.vnet.ibm.com
Mon Mar 5 19:07:32 UTC 2018
On Mon, 2018-03-05 at 20:01 +0200, Jarkko Sakkinen wrote:
> On Mon, Mar 05, 2018 at 12:56:33PM +0200, Jarkko Sakkinen wrote:
> > On Fri, Mar 02, 2018 at 12:26:35AM +0530, Nayna Jain wrote:
> > >
> > >
> > > On 03/01/2018 02:52 PM, Jarkko Sakkinen wrote:
> > > > On Wed, Feb 28, 2018 at 02:18:27PM -0500, Nayna Jain wrote:
> > > > > In tpm_transmit, after send(), the code checks for status in a loop
> > > > Maybe cutting hairs now but please just use the actual function name
> > > > instead of send(). Just makes the commit log more useful asset.
> > > Sure, will do.
> > > >
> > > > > - tpm_msleep(TPM_TIMEOUT);
> > > > > + tpm_msleep(TPM_TIMEOUT_POLL);
> > > > What about just calling schedule()?
> > > I'm not sure what you mean by "schedule()". Are you suggesting instead of
> > > using usleep_range(), using something with an even finer grain construct?
> > >
> > > Thanks & Regards,
> > > - Nayna
> > kernel/sched/core.c
> The question I'm trying ask to is: is it better to sleep such a short
> time or just ask scheduler to schedule something else after each
I still don't understand why scheduling some work would be an
improvement. We still need to loop, testing for the TPM command to
According to the schedule_hrtimeout_range() function comment,
schedule_hrtimeout_range() is both power and performance friendly.
What we didn't realize is that the hrtimer *uses* the maximum range
to calculate the sleep time, but *may* return earlier based on the
This patch minimizes the tpm_msleep(). The subsequent patch in this
patch set shows that 1 msec isn't fine enough granularity. I still
think calling usleep_range() is the right solution, but it needs to be
at a finer granularity than tpm_msleep() provides.
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