linux-kernel - Re: Decreasing time for `rsa

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Date:   Thu, 13 Jul 2017 20:20:41 +0200
From:   Paul Menzel <pmenzel@...gen.mpg.de>
To:     Stephan Müller <smueller@...onox.de>
Cc:     linux-crypto@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: Decreasing time for `rsa_init`

Dear Stephan,


Am Mittwoch, den 12.07.2017, 19:38 +0200 schrieb Paul Menzel:

> On 07/12/17 19:28, Stephan Müller wrote:
> > Am Mittwoch, 12. Juli 2017, 12:59:58 CEST schrieb Paul Menzel:
> > > Building CRYPTO_RSA not as module, but into the Linux kernel,
> > > `rsa_init()` takes 130 ms on an ASRock E350M1.
> > > 
> > > (Timings are shown by adding `initcall_debug` to Linux command
> > > line [1].
> > > The times are visualized by `analyze_boot.py` from pm-graph [2]
> > > or `systemd-bootchart`.)
> > > 
> > > This is quite a lot of time compared to other modules, and I
> > > wonder if
> > > there are ways to decrease that time other than building it as a
> > > module,
> > > and not signing modules?
> > 
> > Is the testmgr compiled? If yes, the self test may take that time.
> 
> It looks like it is, as the tests are not disabled.
> 
> ```
> $ grep MANAGER_DISABLE_TESTS .config
> # CONFIG_CRYPTO_MANAGER_DISABLE_TESTS is not set
> ```
> 
> I’ll try an image without the tests, and will report back.

Thank you. That was it. Disabling the tests reduces the time to 51 μs.

```
kernel: calling  rsa_init+0x0/0x40 @ 1
kernel: initcall rsa_init+0x0/0x40 returned 0 after 51 usecs
```

It’d be nice to be able to disable the testmgr during run-time by
adding an option to the Linux Kernel command line for example.


Kind regards,

Paul


> > > [1] http://elinux.org/Initcall_Debug
> > > [2] https://github.com/01org/pm-graph