svn commit: r355828 - head/sys/sys

[Warner Losh]

On Mon, Dec 16, 2019, 9:42 PM Cy Schubert <Cy.Schubert at cschubert.com> wrote:

> In message <201912162355.xBGNtUq6078840 at repo.freebsd.org>, "Pedro F.
> Giffuni" w
> rites:
> > Author: pfg
> > Date: Mon Dec 16 23:55:30 2019
> > New Revision: 355828
> > URL: https://svnweb.freebsd.org/changeset/base/355828
> >
> > Log:
> >   Double the size of ARG_MAX on LP64 platforms.
> >
> >   As modern software keeps growing in size, we get requests to update the
> >   value of ARG_MAX in order to link the resulting object files. Other OSs
> >   have much higher values but Increasiong ARG_MAX has a multiplied
> effect on
> >   KVA, so just bumping this value is dangerous in some archs like ARM32
> that
> >   can exhaust KVA rather easily.
> >
> >   While it would be better to have a unique value for all archs, other
> OSs
> >   (Illumos in partidular) can have different ARG_MAX limits depending on
> the
> >   platform,  For now we want to be really conservative so we are avoidng
> >   the change on ILP32 and in the alternative case we only double it
> since tha
> > t
> >   seems to work well enough for recent Code Aster.
> >
> >   I was planning to bump the _FreeBSD_version but it was bumped recently
> >   (r355798) so we can reuse the 1300068 value for this change.
>
> This doesn't seem right. Each bump should be for a distinct change and
> documented as such.
>

In the past we've said to piggy back versions when less than a day has
passed since the last bump. The hard part on this is that follow through on
actually documenting both has been lax.

Warner

Also, it's not like we're saving any build time anyway. sys/syslimits.h
> will cause a substantial portion to be rebuilt anyway.
>
> >
> >   PR:         241710
> >   MFC after:  5 days
> >
> > Modified:
> >   head/sys/sys/syslimits.h
> >
> > Modified: head/sys/sys/syslimits.h
> >
> =============================================================================
> > =
> > --- head/sys/sys/syslimits.h  Mon Dec 16 23:08:09 2019        (r355827)
> > +++ head/sys/sys/syslimits.h  Mon Dec 16 23:55:30 2019        (r355828)
> > @@ -48,7 +48,11 @@
> >   * Do not add any new variables here.  (See the comment at the end of
> >   * the file for why.)
> >   */
> > -#define      ARG_MAX                 262144  /* max bytes for an exec
> functi
> > on */
> > +#ifndef __ILP32__
> > +#define      ARG_MAX       (2 * 256 * 1024)  /* max bytes for an exec
> functi
> > on */
> > +#else
> > +#define      ARG_MAX           (256 * 1024)  /* max bytes for
> KVA-starved ar
> > chs */
> > +#endif
> >  #ifndef CHILD_MAX
> >  #define      CHILD_MAX                  40   /* max simultaneous
> processes *
> > /
> >  #endif
> >
>
>
> --
> Cheers,
> Cy Schubert <Cy.Schubert at cschubert.com>
> FreeBSD UNIX:  <cy at FreeBSD.org>   Web:  http://www.FreeBSD.org
>
>         The need of the many outweighs the greed of the few.
>
>
>