svn commit: r253662 - in head: lib/libc/gen sys/vm tools/tools/sysdoc
Juli Mallett
jmallett at FreeBSD.org
Fri Jul 26 21:31:26 UTC 2013
On Fri, Jul 26, 2013 at 2:26 PM, Andrey Zonov <zont at freebsd.org> wrote:
> On 7/26/13 8:09 AM, Jilles Tjoelker wrote:
> > On Fri, Jul 26, 2013 at 02:00:07AM +0000, Andrey Zonov wrote:
> >> Author: zont
> >> Date: Fri Jul 26 02:00:06 2013
> >> New Revision: 253662
> >> URL: http://svnweb.freebsd.org/changeset/base/253662
> >
> >> Log:
> >> Remove define and documentation for vm_pageout_algorithm missed in
> r253587
> >
> >> Modified:
> >> head/lib/libc/gen/sysctl.3
> >> head/sys/vm/vm_param.h
> >> head/tools/tools/sysdoc/tunables.mdoc
> >
> >> Modified: head/sys/vm/vm_param.h
> >>
> ==============================================================================
> >> --- head/sys/vm/vm_param.h Fri Jul 26 00:28:19 2013 (r253661)
> >> +++ head/sys/vm/vm_param.h Fri Jul 26 02:00:06 2013 (r253662)
> >> @@ -82,9 +82,8 @@
> >> #define VM_V_CACHE_MIN 7 /* cnt.v_cache_min */
> >> #define VM_V_CACHE_MAX 8 /* cnt.v_cache_max */
> >> #define VM_V_PAGEOUT_FREE_MIN 9 /* cnt.v_pageout_free_min
> */
> >> -#define VM_PAGEOUT_ALGORITHM 10 /* pageout algorithm */
> >> -#define VM_SWAPPING_ENABLED 11 /* swapping enabled */
> >> -#define VM_MAXID 12 /* number of valid vm ids
> */
> >> +#define VM_SWAPPING_ENABLED 10 /* swapping enabled */
> >> +#define VM_MAXID 11 /* number of valid vm ids
> */
> >
> > As noted in mail from Bruce Evans, please preserve the ABI of
> > VM_SWAPPING_ENABLED here.
> >
>
> I don't think it's a big problem. Internally we don't use it. Good
> code uses sysctlbyname() instead of sysctl(). It doesn't seem to me
> this is very popular sysctl. It's also CURRENT without MFC.
That doesn't seem like a great argument.
Why should we break the ABI for bad code that used that sysctl and all
following? It seems pretty trivial to preserve, and no-cost. Also, the
fact that it's in current misses the point completely: it breaks ABI with
older binaries, namely older binaries running on -CURRENT. And not just
for that field.
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