[PATCH] x86: Add thresholds for "rep movsb/stosb" to tunables

[H.J. Lu]

On Mon, Jun 1, 2020 at 1:57 PM Carlos O'Donell <carlos@redhat.com> wrote:
>
> On Mon, Jun 1, 2020 at 4:48 PM Florian Weimer <fw@deneb.enyo.de> wrote:
> >
> > * H. J. Lu via Libc-alpha:
> >
> > > On Mon, Jun 1, 2020 at 1:15 PM H.J. Lu <hjl.tools@gmail.com> wrote:
> > >>
> > >> On Mon, Jun 1, 2020 at 12:38 PM Carlos O'Donell <carlos@redhat.com> wrote:
> > >> >
> > >> > On Mon, Jun 1, 2020 at 3:33 PM H.J. Lu <hjl.tools@gmail.com> wrote:
> > >> > > Did you mean adding  --list-tunables to ld.so?  libc.so.6 doesn't take
> > >> > > any arguments.
> > >> >
> > >> > Yes, I mean adding argument processing to libc.so.6, and handling
> > >> > --list-tunables.
> > >> >
> > >> > We have enough infrastructure in place that wiring that up shouldn't be too bad?
> > >> >
> > >> > Then, even in trimmed down containers, you can just run
> > >> > /lib64/libc.so.6 --list-tunables and get back the list of tunables and
> > >> > their min, max, and security values.
> > >>
> > >> Adding an argument to libc.so.6 is difficult since argument passing is
> > >> processor specific.  Adding --list-tunables to ld.so? is more doable.
> > >
> > > But tunables are in libc.so.
> >
> > If this is really a problem, we can load libc.so and call a
> > GLIBC_PRIVATE function to print the information.
>
> Agreed.
>
> Please keep in mind the original problem we are trying to solve.
>
> We want a tunable for a parameter that is difficult to explain to the user.
>
> To make it easier for our users to use the tunable we are going to
> provide them a way to look at the tunable settings in detail.
>
> Yes, it requires a target system, but we can't avoid that in some cases.
>

Something like this?

-- 
H.J.
-------------- next part --------------
A non-text attachment was scrubbed...
Name: 0001-x86-Pass-argc-and-argv-to-__libc_main.patch
Type: text/x-patch
Size: 7825 bytes
Desc: not available
URL: <https://sourceware.org/pipermail/libc-alpha/attachments/20200601/1a0f382e/attachment.bin>