GDK_mmap_minsize again

Roberto Cornacchia roberto.cornacchia at gmail.com
Tue Sep 20 18:40:41 CEST 2016


If I may add, that is indeed the default behaviour of the kernel, which can
be disabled with

vm.overcommit_memory = 2
in /etc/sysctl.conf

Perhaps MonetDB could check this system setting and decide on which
strategy to use?

On 20 September 2016 at 18:24, Sjoerd Mullender <sjoerd at acm.org> wrote:

> As far as I understand it, malloc on Linux will happily succeed even if
> there is not enough memory+swap to hold all data.  So you can't rely on
> malloc failures to tell you to switch to mmap.
>
> On 09/20/2016 06:19 PM, Hannes Mühleisen wrote:
> > Hello list,
> >
> > we were wondering about the purpose of GDK_mmap_minsize when creating
> transient columns. The attached patch will always *try* to malloc/realloc a
> transient column but still fall back to memory-mapped files if malloc
> should fail. This dramatically improves performance. Any good reason why
> this should not be the default behaviour?
> >
> > Thanks,
> >
> > Mark and Hannes
> >
> >
> >
>
> --
> Sjoerd Mullender
>
>
>
> --
> Sjoerd Mullender
>
>
> _______________________________________________
> developers-list mailing list
> developers-list at monetdb.org
> https://www.monetdb.org/mailman/listinfo/developers-list
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://www.monetdb.org/pipermail/developers-list/attachments/20160920/9adf2a81/attachment.html>


More information about the developers-list mailing list