We currently have RESIDENT set to -1, if I increase BUFFERS above 2M I get
the message

07:55:17 Informix Dynamic Server Stopped.
07:56:49 mt_shm_init: can't create resident segment

When I change RESIDENT to 0, I can increase the buffers to whatever I want.
I know why I'm getting this error, that is not the reason for this posting.
What I'm looking for is an informed opinion of why set RESIDENT to -1 in the
first place, Is there a real benefit or only a percieved one?





Regards

Colin Dawson


sending to informix-list

What platform are you on?

Making memory resident that is not paged out anyway may not make sense.
But on Solaris the "RESIDENT -1" setting has a second effect: It creates
shared memory with a page size of 4 MB instead of 8k pages (using the
SHM_SHARE_MMU flag of shmat()). This speeds up physical to virtual page
translation in the cpu and has a performance benefit on large systems.

Michael

Colin Dawson wrote:
> We currently have RESIDENT set to -1, if I increase BUFFERS above 2M I get
> the message
>
> 07:55:17 Informix Dynamic Server Stopped.
> 07:56:49 mt_shm_init: can't create resident segment
>
> When I change RESIDENT to 0, I can increase the buffers to whatever I want.
> I know why I'm getting this error, that is not the reason for this posting.
> What I'm looking for is an informed opinion of why set RESIDENT to -1 in the
> first place, Is there a real benefit or only a percieved one?
>
>
>
>
>
> Regards
>
> Colin Dawson
>
>
> sending to informix-list