Re: SHM_LOCK under Linux ... do we use this?

""Marc G. Fournier"" <scrappy@postgresql.org> writes
>
> I've done a grep through the code, to see if its something that we do use,
and
> it doesn't seem to come back with anything ... I believe its considered
> common knowledge that 'swapping' for a database is evil, so am wondering
> if there is some way that we can make use of this to help reduce/eliminate
> that from happening?
>

There are some similar flags in other OS could help us to keep the memory
resident in. However, it is not always a net win if we force it. This is
because other parts of the system (like fork a process) may need memory, so
the OS will pick up the "coldest" memory to be swapped. If we have already
use our memory intensively, I don't think we will be swapped. On the
contrary, if we force OS not to swap some memory, we may get other penalties
like our processes have to be sarcrificed.

Regards,
Qingqing