On Mon, Jun 11, 2018 at 05:13:34PM -0700, Tadeusz Struk wrote: > On 06/08/2018 12:36 PM, flihp wrote: > > On 06/04/2018 12:55 PM, Jarkko Sakkinen wrote: > >> On Thu, May 31, 2018 at 04:29:09PM -0700, Tadeusz Struk wrote: > >>> The TCG SAPI specification [1] defines a set of functions, which allows > >>> applications to use the TPM device in either blocking or non-blocking fashion. > >>> Each command defined by the specification has a corresponding > >>> Tss2_Sys_<COMMAND>_Prepare() and Tss2_Sys_<COMMAND>_Complete() call, which > >>> together with Tss2_Sys_ExecuteAsync() is designed to allow asynchronous > >>> mode of operation. Currently the driver supports only blocking calls, which > >>> doesn't allow asynchronous operation. This patch changes it and adds support > >>> for nonblocking write and a new poll function to enable applications using > >>> the API as designed by the spec. > >>> The new functionality can be tested using standard TPM tools implemented > >>> in [2], with modified TCTI from [3]. > >> > >> I would need some statistics before I have interest to take these > >> changes in any form eg use case where this matters in the end. > > > > The use cases motivating this feature are the same ones that motivated > > the non-blocking behavior of other kernel interfaces (files, sockets and > > other hardware) that has the potential to block threads in a process. By > > implementing this same behavior in the TPM driver our goal is to enable > > use of the TPM in programming languages / frameworks implementing an > > "event-driven" model. There are a lot of them out there but since the > > TSS2 APIs are currently limited to C our example code is in glib / GSource. > > > > Hopefully this is sufficient but if it isn't it would help us to get > > additional details on what you're looking for. > > I tried to run some tests w/r/t blocking to non-blocking. > and for example for tpm2_createprimary (type RSA) it looks more less like this: > blocking: > real 0m3.194s > user 0m0.052s > sys 0m0.094s > > vs nonblocking: > real 0m1.031s > user 0m0.043s > sys 0m0.162s > > that's on Minnowboard Turbot D0 PLATFORM > running FW Version: MNW2MAX1.X64.0097.R01.1709211204 > > The number are different every time I run it though. > Is this what you wanted to see? Thanks, this and Philips explanation make it worth of looking into! /Jarkko
