HPUX 11.31 -> Disabling Pseudo-Swap??

[PatRoy]

Don, I'm trying to get your object_dump going, but I can't see how to get a complete listing of all PIDs, or just one. I've tried with 'object_dump v', but it's always giving the same thing :

On system being idle (no Sybase running):

VIRT/PHYS/LOCKED/SWAP summaries in pages.
System page size is 4096 or 0x1000 bytes.
Total physical memory is bfde85 pages (49118 Mb).
Maximum allocatable User memory is b01b9a pages (45083 Mb).
System Wide Mb in Use:
Virt: 8131 Phys: 1044 Swap: 467

and when Sybase is running:

VIRT/PHYS/LOCKED/SWAP summaries in pages.
System page size is 4096 or 0x1000 bytes.
Total physical memory is bfde85 pages (49118 Mb).
Maximum allocatable User memory is b01b9b pages (45083 Mb).
System Wide Mb in Use:
Virt: 192827 Phys: 23315 Swap: 181281

I tried looking at the source code to see what arguments it needed, but it's not working?? Cna you clarify?

Thanks again.

[Don Morris_1]

"object_dump -v" (the dash is important).

[PatRoy]

Okay. I seem to be getting a few things here.

When we mlock, it doesn't actually "lock" the memory. It's more that it's going to reserve swap, which would prevent other apps from using memory that can't reserve it's swap for... It first does so by reserving all it can in the physical swap devices, then will go to the pseudo pool if there's not enough in the physical.

I'm still waiting on HP to call me back and explain a few things though...

From my findings (trial & error), I quote myself:

"Basically, we need to understand why is it that if I've got only one 10Gb swap device with 48 physical RAM, I'm able to mlock 36Gbs, but if I add another 26Gb swap device (bringing me to 36Gb total), I am not able to mlock 38Gbs (just a mear 2Gbs more). I went crazy brought my physical swap to 48Gbs instead, and then I was able to mlock more then 38 (limit was not approx 43gbs)". See attachment for details.

I don't get it!

Yet another important piece of information dmesg gave us that we totally missed:

Memory Information:
physical page size = 4096 bytes, logical page size = 4096 bytes
Physical: 50297364 Kbytes, lockable: 37945556 Kbytes, available: 43186360 Kbytes

It says right there! 36Gbs is the lockable memory (which was our initial limit before me increasing the swap to 48Gbs... even though increasing it an extra 26G didn't work).

I'm just looking to understand a bit more here. I'll probably end telling our DBAs that they can't lock more then 35Gbs. Bottom line! Explaining that it's not because we've got 48Gbs of ram that we need to max it out! (it's plain stupid!)

But this is more for our own knowledge... to also try to understand at what point would it start paging out (if it would) if we were to lock that 43Gbs...

Thanks, P.

[Dennis Handly]

>When we mlock, it doesn't actually "lock" the memory.

The man page says it locks it in memory, so adding swap doesn't help:
The mlock() system call allows the calling process to lock a segment of the process virtual address space into memory. Any addressable segment of the process' address space may be locked. Locked segments are immune to all routine swapping.

[PatRoy]

>The mlock() system call allows the calling process to lock a segment of the process virtual address space...

Isn't talking about virtual memory here? If so, then isn't VM by definition: "The entire memory space available to the Unix Kernel. This consists of both the physical memory and all swap space."

If that's the case, then, in theory, it just seems normal that adding swap device would help. No?

[Dennis Handly]

>Isn't it talking about virtual memory here?

No. Since it says: Locked segments are immune to all routine swapping.
It is talking about memory.