[PATCH] rng-tools: disable libjitterentropy due to cpu usage

[PATCH] rng-tools: disable libjitterentropy due to cpu usage

[Wes Malone]

Since updating to kirkstone from hardknott, after boot rngd maxes out my
rpi4's processor for minutes initializing JITTER. The sustained CPU
usage was triggering my resource monitoring alerts. Changing config to
disable jitter with -x jitter stops the initialization process and uses
just the pi's hardware rng source. Since that solved the problem I
disabled building rng-tools with libjitterentropy enabled.

I submitted the change to meta-raspberrypi (pull #1057) where kraj noted
that the CPU spike is seen even on qemu so the change should go in the
core layer.

[PATCH] rng-tools: disable libjitterentropy due to cpu usage

[Wes Malone]

After boot rngd maxes out the processor initializing JITTER entropy for
some minutes. Here we disable libjitterentropy in favor of only using
the hardware random source via config.

Signed-off-by: Wes Malone <wes@mitsi.com>
---
 meta/recipes-support/rng-tools/rng-tools_6.15.bb | 1 -
 1 file changed, 1 deletion(-)

diff --git a/meta/recipes-support/rng-tools/rng-tools_6.15.bb b/meta/recipes-support/rng-tools/rng-tools_6.15.bb
index 0696351903..4eed060960 100644
--- a/meta/recipes-support/rng-tools/rng-tools_6.15.bb
+++ b/meta/recipes-support/rng-tools/rng-tools_6.15.bb
@@ -21,7 +21,6 @@ inherit autotools update-rc.d systemd pkgconfig
 
 EXTRA_OECONF = "--without-rtlsdr"
 
-PACKAGECONFIG ??= "libjitterentropy"
 PACKAGECONFIG:libc-musl = "libargp libjitterentropy"
 
 PACKAGECONFIG[libargp] = "--with-libargp,--without-libargp,argp-standalone,"
-- 
2.36.0

Re: [OE-core] [PATCH] rng-tools: disable libjitterentropy due to cpu usage

[William Kennington]

Isn't this desirable if you don't have an hwrng? We want to generate
entropy so we can perform cryptographic operations by default if we
bring in rng-tools.

On Mon, May 2, 2022 at 2:10 PM Wes Malone <wes@mitsi.com> wrote:
>
> After boot rngd maxes out the processor initializing JITTER entropy for
> some minutes. Here we disable libjitterentropy in favor of only using
> the hardware random source via config.
>
> Signed-off-by: Wes Malone <wes@mitsi.com>
> ---
>  meta/recipes-support/rng-tools/rng-tools_6.15.bb | 1 -
>  1 file changed, 1 deletion(-)
>
> diff --git a/meta/recipes-support/rng-tools/rng-tools_6.15.bb b/meta/recipes-support/rng-tools/rng-tools_6.15.bb
> index 0696351903..4eed060960 100644
> --- a/meta/recipes-support/rng-tools/rng-tools_6.15.bb
> +++ b/meta/recipes-support/rng-tools/rng-tools_6.15.bb
> @@ -21,7 +21,6 @@ inherit autotools update-rc.d systemd pkgconfig
>
>  EXTRA_OECONF = "--without-rtlsdr"
>
> -PACKAGECONFIG ??= "libjitterentropy"
>  PACKAGECONFIG:libc-musl = "libargp libjitterentropy"
>
>  PACKAGECONFIG[libargp] = "--with-libargp,--without-libargp,argp-standalone,"
> --
> 2.36.0
>
>
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Re: [OE-core] [PATCH] rng-tools: disable libjitterentropy due to cpu usage

[Alexander Kanavin]

[-- Attachment #1: Type: text/plain, Size: 1967 bytes --]

Yes, I wonder why this needs to be disabled altogether at build time. Can’t
rng-tools figure out the right sources at run time?

Alex

On Mon 2. May 2022 at 23.33, William A. Kennington III via
lists.openembedded.org <wak=google.com@lists.openembedded.org> wrote:

> Isn't this desirable if you don't have an hwrng? We want to generate
> entropy so we can perform cryptographic operations by default if we
> bring in rng-tools.
>
> On Mon, May 2, 2022 at 2:10 PM Wes Malone <wes@mitsi.com> wrote:
> >
> > After boot rngd maxes out the processor initializing JITTER entropy for
> > some minutes. Here we disable libjitterentropy in favor of only using
> > the hardware random source via config.
> >
> > Signed-off-by: Wes Malone <wes@mitsi.com>
> > ---
> >  meta/recipes-support/rng-tools/rng-tools_6.15.bb | 1 -
> >  1 file changed, 1 deletion(-)
> >
> > diff --git a/meta/recipes-support/rng-tools/rng-tools_6.15.bb
> b/meta/recipes-support/rng-tools/rng-tools_6.15.bb
> > index 0696351903..4eed060960 100644
> > --- a/meta/recipes-support/rng-tools/rng-tools_6.15.bb
> > +++ b/meta/recipes-support/rng-tools/rng-tools_6.15.bb
> > @@ -21,7 +21,6 @@ inherit autotools update-rc.d systemd pkgconfig
> >
> >  EXTRA_OECONF = "--without-rtlsdr"
> >
> > -PACKAGECONFIG ??= "libjitterentropy"
> >  PACKAGECONFIG:libc-musl = "libargp libjitterentropy"
> >
> >  PACKAGECONFIG[libargp] =
> "--with-libargp,--without-libargp,argp-standalone,"
> > --
> > 2.36.0
> >
> >
> >
> >
>
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[-- Attachment #2: Type: text/html, Size: 3540 bytes --]

Re: [OE-core] [PATCH] rng-tools: disable libjitterentropy due to cpu usage

[Wes Malone]

> Isn't this desirable if you don't have an hwrng?
Perhaps what's needed then is a 'hwrng' in MACHINE_FEATURES?

> Can’t rng-tools figure out the right sources at run time?
rng-tools enables jitter by default if it's built in, even if hwrng is
available. Maybe it's faster to do this on more powerful machines but
it's disruptive to run the cpu at max for so long on my pi's.

We could also disable it with the /etc/defaults file with `-x jitter`.


On Mon, May 2, 2022 at 11:47 PM Alexander Kanavin
<alex.kanavin@gmail.com> wrote:
>
> Yes, I wonder why this needs to be disabled altogether at build time. Can’t rng-tools figure out the right sources at run time?
>
> Alex
>
> On Mon 2. May 2022 at 23.33, William A. Kennington III via lists.openembedded.org <wak=google.com@lists.openembedded.org> wrote:
>>
>> Isn't this desirable if you don't have an hwrng? We want to generate
>> entropy so we can perform cryptographic operations by default if we
>> bring in rng-tools.
>>
>> On Mon, May 2, 2022 at 2:10 PM Wes Malone <wes@mitsi.com> wrote:
>> >
>> > After boot rngd maxes out the processor initializing JITTER entropy for
>> > some minutes. Here we disable libjitterentropy in favor of only using
>> > the hardware random source via config.
>> >
>> > Signed-off-by: Wes Malone <wes@mitsi.com>
>> > ---
>> >  meta/recipes-support/rng-tools/rng-tools_6.15.bb | 1 -
>> >  1 file changed, 1 deletion(-)
>> >
>> > diff --git a/meta/recipes-support/rng-tools/rng-tools_6.15.bb b/meta/recipes-support/rng-tools/rng-tools_6.15.bb
>> > index 0696351903..4eed060960 100644
>> > --- a/meta/recipes-support/rng-tools/rng-tools_6.15.bb
>> > +++ b/meta/recipes-support/rng-tools/rng-tools_6.15.bb
>> > @@ -21,7 +21,6 @@ inherit autotools update-rc.d systemd pkgconfig
>> >
>> >  EXTRA_OECONF = "--without-rtlsdr"
>> >
>> > -PACKAGECONFIG ??= "libjitterentropy"
>> >  PACKAGECONFIG:libc-musl = "libargp libjitterentropy"
>> >
>> >  PACKAGECONFIG[libargp] = "--with-libargp,--without-libargp,argp-standalone,"
>> > --
>> > 2.36.0
>> >
>> >
>> >
>> >
>>
>> -=-=-=-=-=-=-=-=-=-=-=-
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>> Mute This Topic: https://lists.openembedded.org/mt/90845997/1686489
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>> Unsubscribe: https://lists.openembedded.org/g/openembedded-core/unsub [alex.kanavin@gmail.com]
>> -=-=-=-=-=-=-=-=-=-=-=-
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Re: [OE-core] [PATCH] rng-tools: disable libjitterentropy due to cpu usage

[Khem Raj]

On Tue, May 3, 2022 at 8:23 AM Wes Malone <wes@mitsi.com> wrote:
>
> > Isn't this desirable if you don't have an hwrng?
> Perhaps what's needed then is a 'hwrng' in MACHINE_FEATURES?
>
> > Can’t rng-tools figure out the right sources at run time?
> rng-tools enables jitter by default if it's built in, even if hwrng is
> available. Maybe it's faster to do this on more powerful machines but
> it's disruptive to run the cpu at max for so long on my pi's.
>
> We could also disable it with the /etc/defaults file with `-x jitter`.
>

I wonder if rng-tools is still needed after 5.6+ kernel after this commit [1]
Arch Linux wiki says no [2]. We added this as a recommendation to
openssh by default [3] [4],
I wonder if we can turn that off by default and perhaps add havaged as
dependency if needed.
[5] changed to use /dev/hwrng which seems right change to me. I also
wonder if we can tune
the resource requirement for rng-tools with limiting cpu threads and
buffers allocated for this.

[1] https://github.com/torvalds/linux/commit/30c08efec8884fb106b8e57094baa51bb4c44e32
[2] https://wiki.archlinux.org/title/Rng-tools
[3] https://git.openembedded.org/openembedded-core/commit/?id=9b01375236e19e3366c58877c4154d7c71632984
[4] https://git.openembedded.org/openembedded-core/commit/?id=fe99349c1bd72b69d22ab0dc52b8825d3157b8e7
[5] https://git.openembedded.org/openembedded-core/commit/?id=f1dc9ac46710814c27cae2d22e79c84a9522993a

>
> On Mon, May 2, 2022 at 11:47 PM Alexander Kanavin
> <alex.kanavin@gmail.com> wrote:
> >
> > Yes, I wonder why this needs to be disabled altogether at build time. Can’t rng-tools figure out the right sources at run time?
> >
> > Alex
> >
> > On Mon 2. May 2022 at 23.33, William A. Kennington III via lists.openembedded.org <wak=google.com@lists.openembedded.org> wrote:
> >>
> >> Isn't this desirable if you don't have an hwrng? We want to generate
> >> entropy so we can perform cryptographic operations by default if we
> >> bring in rng-tools.
> >>
> >> On Mon, May 2, 2022 at 2:10 PM Wes Malone <wes@mitsi.com> wrote:
> >> >
> >> > After boot rngd maxes out the processor initializing JITTER entropy for
> >> > some minutes. Here we disable libjitterentropy in favor of only using
> >> > the hardware random source via config.
> >> >
> >> > Signed-off-by: Wes Malone <wes@mitsi.com>
> >> > ---
> >> >  meta/recipes-support/rng-tools/rng-tools_6.15.bb | 1 -
> >> >  1 file changed, 1 deletion(-)
> >> >
> >> > diff --git a/meta/recipes-support/rng-tools/rng-tools_6.15.bb b/meta/recipes-support/rng-tools/rng-tools_6.15.bb
> >> > index 0696351903..4eed060960 100644
> >> > --- a/meta/recipes-support/rng-tools/rng-tools_6.15.bb
> >> > +++ b/meta/recipes-support/rng-tools/rng-tools_6.15.bb
> >> > @@ -21,7 +21,6 @@ inherit autotools update-rc.d systemd pkgconfig
> >> >
> >> >  EXTRA_OECONF = "--without-rtlsdr"
> >> >
> >> > -PACKAGECONFIG ??= "libjitterentropy"
> >> >  PACKAGECONFIG:libc-musl = "libargp libjitterentropy"
> >> >
> >> >  PACKAGECONFIG[libargp] = "--with-libargp,--without-libargp,argp-standalone,"
> >> > --
> >> > 2.36.0
> >> >
> >> >
> >> >
> >> >
> >>
> >>
> >>
>
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Re: [OE-core] [PATCH] rng-tools: disable libjitterentropy due to cpu usage

[Wes Malone]

I'm not well versed enough in these details to make a decision but I'd
like to help fix it once the decision is made. I of course moved on
with a small append on my end but I'd like to help fix this since it
affected my project.

On Tue, May 3, 2022 at 11:21 AM Khem Raj <raj.khem@gmail.com> wrote:
>
> On Tue, May 3, 2022 at 8:23 AM Wes Malone <wes@mitsi.com> wrote:
> >
> > > Isn't this desirable if you don't have an hwrng?
> > Perhaps what's needed then is a 'hwrng' in MACHINE_FEATURES?
> >
> > > Can’t rng-tools figure out the right sources at run time?
> > rng-tools enables jitter by default if it's built in, even if hwrng is
> > available. Maybe it's faster to do this on more powerful machines but
> > it's disruptive to run the cpu at max for so long on my pi's.
> >
> > We could also disable it with the /etc/defaults file with `-x jitter`.
> >
>
> I wonder if rng-tools is still needed after 5.6+ kernel after this commit [1]
> Arch Linux wiki says no [2]. We added this as a recommendation to
> openssh by default [3] [4],
> I wonder if we can turn that off by default and perhaps add havaged as
> dependency if needed.
> [5] changed to use /dev/hwrng which seems right change to me. I also
> wonder if we can tune
> the resource requirement for rng-tools with limiting cpu threads and
> buffers allocated for this.
>
> [1] https://github.com/torvalds/linux/commit/30c08efec8884fb106b8e57094baa51bb4c44e32
> [2] https://wiki.archlinux.org/title/Rng-tools
> [3] https://git.openembedded.org/openembedded-core/commit/?id=9b01375236e19e3366c58877c4154d7c71632984
> [4] https://git.openembedded.org/openembedded-core/commit/?id=fe99349c1bd72b69d22ab0dc52b8825d3157b8e7
> [5] https://git.openembedded.org/openembedded-core/commit/?id=f1dc9ac46710814c27cae2d22e79c84a9522993a
>
> >
> > On Mon, May 2, 2022 at 11:47 PM Alexander Kanavin
> > <alex.kanavin@gmail.com> wrote:
> > >
> > > Yes, I wonder why this needs to be disabled altogether at build time. Can’t rng-tools figure out the right sources at run time?
> > >
> > > Alex
> > >
> > > On Mon 2. May 2022 at 23.33, William A. Kennington III via lists.openembedded.org <wak=google.com@lists.openembedded.org> wrote:
> > >>
> > >> Isn't this desirable if you don't have an hwrng? We want to generate
> > >> entropy so we can perform cryptographic operations by default if we
> > >> bring in rng-tools.
> > >>
> > >> On Mon, May 2, 2022 at 2:10 PM Wes Malone <wes@mitsi.com> wrote:
> > >> >
> > >> > After boot rngd maxes out the processor initializing JITTER entropy for
> > >> > some minutes. Here we disable libjitterentropy in favor of only using
> > >> > the hardware random source via config.
> > >> >
> > >> > Signed-off-by: Wes Malone <wes@mitsi.com>
> > >> > ---
> > >> >  meta/recipes-support/rng-tools/rng-tools_6.15.bb | 1 -
> > >> >  1 file changed, 1 deletion(-)
> > >> >
> > >> > diff --git a/meta/recipes-support/rng-tools/rng-tools_6.15.bb b/meta/recipes-support/rng-tools/rng-tools_6.15.bb
> > >> > index 0696351903..4eed060960 100644
> > >> > --- a/meta/recipes-support/rng-tools/rng-tools_6.15.bb
> > >> > +++ b/meta/recipes-support/rng-tools/rng-tools_6.15.bb
> > >> > @@ -21,7 +21,6 @@ inherit autotools update-rc.d systemd pkgconfig
> > >> >
> > >> >  EXTRA_OECONF = "--without-rtlsdr"
> > >> >
> > >> > -PACKAGECONFIG ??= "libjitterentropy"
> > >> >  PACKAGECONFIG:libc-musl = "libargp libjitterentropy"
> > >> >
> > >> >  PACKAGECONFIG[libargp] = "--with-libargp,--without-libargp,argp-standalone,"
> > >> > --
> > >> > 2.36.0
> > >> >
> > >> >
> > >> >
> > >> >
> > >>
> > >>
> > >>
> >
> > -=-=-=-=-=-=-=-=-=-=-=-
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> > Unsubscribe: https://lists.openembedded.org/g/openembedded-core/unsub [raj.khem@gmail.com]
> > -=-=-=-=-=-=-=-=-=-=-=-
> >

Re: [OE-core] [PATCH] rng-tools: disable libjitterentropy due to cpu usage

[Khem Raj]

one way is to make rng-tools use less resources on embedded devices
perhaps limit the number of cores its give and buffer sizes.
secondly send a patch to remove openssh dependency on rng-tools perhaps

On Thu, May 5, 2022 at 2:34 PM Wes Malone <wes@mitsi.com> wrote:
>
> I'm not well versed enough in these details to make a decision but I'd
> like to help fix it once the decision is made. I of course moved on
> with a small append on my end but I'd like to help fix this since it
> affected my project.
>
> On Tue, May 3, 2022 at 11:21 AM Khem Raj <raj.khem@gmail.com> wrote:
> >
> > On Tue, May 3, 2022 at 8:23 AM Wes Malone <wes@mitsi.com> wrote:
> > >
> > > > Isn't this desirable if you don't have an hwrng?
> > > Perhaps what's needed then is a 'hwrng' in MACHINE_FEATURES?
> > >
> > > > Can’t rng-tools figure out the right sources at run time?
> > > rng-tools enables jitter by default if it's built in, even if hwrng is
> > > available. Maybe it's faster to do this on more powerful machines but
> > > it's disruptive to run the cpu at max for so long on my pi's.
> > >
> > > We could also disable it with the /etc/defaults file with `-x jitter`.
> > >
> >
> > I wonder if rng-tools is still needed after 5.6+ kernel after this commit [1]
> > Arch Linux wiki says no [2]. We added this as a recommendation to
> > openssh by default [3] [4],
> > I wonder if we can turn that off by default and perhaps add havaged as
> > dependency if needed.
> > [5] changed to use /dev/hwrng which seems right change to me. I also
> > wonder if we can tune
> > the resource requirement for rng-tools with limiting cpu threads and
> > buffers allocated for this.
> >
> > [1] https://github.com/torvalds/linux/commit/30c08efec8884fb106b8e57094baa51bb4c44e32
> > [2] https://wiki.archlinux.org/title/Rng-tools
> > [3] https://git.openembedded.org/openembedded-core/commit/?id=9b01375236e19e3366c58877c4154d7c71632984
> > [4] https://git.openembedded.org/openembedded-core/commit/?id=fe99349c1bd72b69d22ab0dc52b8825d3157b8e7
> > [5] https://git.openembedded.org/openembedded-core/commit/?id=f1dc9ac46710814c27cae2d22e79c84a9522993a
> >
> > >
> > > On Mon, May 2, 2022 at 11:47 PM Alexander Kanavin
> > > <alex.kanavin@gmail.com> wrote:
> > > >
> > > > Yes, I wonder why this needs to be disabled altogether at build time. Can’t rng-tools figure out the right sources at run time?
> > > >
> > > > Alex
> > > >
> > > > On Mon 2. May 2022 at 23.33, William A. Kennington III via lists.openembedded.org <wak=google.com@lists.openembedded.org> wrote:
> > > >>
> > > >> Isn't this desirable if you don't have an hwrng? We want to generate
> > > >> entropy so we can perform cryptographic operations by default if we
> > > >> bring in rng-tools.
> > > >>
> > > >> On Mon, May 2, 2022 at 2:10 PM Wes Malone <wes@mitsi.com> wrote:
> > > >> >
> > > >> > After boot rngd maxes out the processor initializing JITTER entropy for
> > > >> > some minutes. Here we disable libjitterentropy in favor of only using
> > > >> > the hardware random source via config.
> > > >> >
> > > >> > Signed-off-by: Wes Malone <wes@mitsi.com>
> > > >> > ---
> > > >> >  meta/recipes-support/rng-tools/rng-tools_6.15.bb | 1 -
> > > >> >  1 file changed, 1 deletion(-)
> > > >> >
> > > >> > diff --git a/meta/recipes-support/rng-tools/rng-tools_6.15.bb b/meta/recipes-support/rng-tools/rng-tools_6.15.bb
> > > >> > index 0696351903..4eed060960 100644
> > > >> > --- a/meta/recipes-support/rng-tools/rng-tools_6.15.bb
> > > >> > +++ b/meta/recipes-support/rng-tools/rng-tools_6.15.bb
> > > >> > @@ -21,7 +21,6 @@ inherit autotools update-rc.d systemd pkgconfig
> > > >> >
> > > >> >  EXTRA_OECONF = "--without-rtlsdr"
> > > >> >
> > > >> > -PACKAGECONFIG ??= "libjitterentropy"
> > > >> >  PACKAGECONFIG:libc-musl = "libargp libjitterentropy"
> > > >> >
> > > >> >  PACKAGECONFIG[libargp] = "--with-libargp,--without-libargp,argp-standalone,"
> > > >> > --
> > > >> > 2.36.0
> > > >> >
> > > >> >
> > > >> >
> > > >> >
> > > >>
> > > >>
> > > >>
> > >
> > > -=-=-=-=-=-=-=-=-=-=-=-
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> > > Unsubscribe: https://lists.openembedded.org/g/openembedded-core/unsub [raj.khem@gmail.com]
> > > -=-=-=-=-=-=-=-=-=-=-=-
> > >