On Sun, May 15, 2011 at 11:49:24AM +0200, Fabian Groffen wrote:
> On 13-05-2011 19:20:44 +0200, Fabian Groffen wrote:
> > Changeset: fc6142f33071 for MonetDB
> > URL: http://dev.monetdb.org/hg/MonetDB?cmd=changeset;node=fc6142f33071
> > Modified Files:
> > configure.ag
> > gdk/gdk_utils.mx
> > Branch: default
> > Log Message:
> >
> > memory: drop getrlimit code block
>
> This change improved performance dramatically on the Mac:
> http://monetdb.cwi.nl/testing/projects/monetdb/testweb/web/testgrid.php?serial=40197:fc6142f33071,40195:dcb51041c4a0&module=clients,geom,monetdb5,template,sql&targets=GNU-Darwin-x86_64-propcheck&order=platform,compiler,arch
>
> Given the extreme performance win, should we consider backporting it to
> Apr2011 branch?
Yes, I would suggest so --- even if only for testing how it works with the
Apr2011 branch --- it does change some behaviour (or removes a "feature" for
that matter, though I understand that the implementation was not suitable to
relyably achieve the intention of the feature ...), but it also fixes a bug
(at least on MacOS) ...
Do you/we (still) run any of the nightly testing machines with restricted
ulimits?
Stefan
ps: If the feature is indeed required, we will have to look for a relyably
working solution, anyway ...
> > The getrlimit approach was meant to detect memory-limited environments,
> > however, in practice it never does what it was supposed to do (except on
> > Solaris).
> >
> > On Darwin, the data size is by default set to 6MiB, causing a default of
> > 6MiB memory to be detected. We can in reality allocate much more than
> > that. The OS uses it as hint for victim choosing when memory shortage
> > occurs anyway. On Linux the limit is never respected. In short, nice
> > idea, but it doesn't quite work out as intended, and only seems to
> > confuse.
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>
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