Re: shmmax

Janne Johansson <icepic.dz@gmail.com> wrote:

> > I'm here asking what
> > it is exactly the meaning for 'shared memory' here, and if implying
> > that it is eventually the max memory allocable to the graphic card
> > is correct.
>
> No. This is not related to graphics card memory


Seems this tweak needs a vast knowledge, a certain kind
of usage profile and some practicality with the system tools..
However, I did my homework and I didn't observe any practical
difference:


I tried this:

sysctl kern.shminfo.shmmax=16777216

start:
wiz# vmstat -f
3460 forks, 81357 pages, average 23.51
12 vforks, 678 pages, average 56.50
2202 __tforks, 0 pages, average 0.00
49 kthread creations, 0 pages, average 0.00

launching some apps (NetBeans, Firefox)

end:
wiz# vmstat -f
3706 forks, 87817 pages, average 23.70
14 vforks, 689 pages, average 49.21
2297 __tforks, 0 pages, average 0.00
49 kthread creations, 0 pages, average 0.00


then:

sysctl kern.shminfo.shmmax=524288

start:
wiz# vmstat -f
3761 forks, 89282 pages, average 23.74
14 vforks, 689 pages, average 49.21
2308 __tforks, 0 pages, average 0.00
49 kthread creations, 0 pages, average 0.00

launching some apps (NetBeans, Firefox)

end:
wiz# vmstat -f
4003 forks, 95495 pages, average 23.86
16 vforks, 699 pages, average 43.69
2389 __tforks, 0 pages, average 0.00
49 kthread creations, 0 pages, average 0.00

then:

sysctl kern.shminfo.shmmax=33554432

start:
wiz# vmstat -f
4107 forks, 97977 pages, average 23.86
16 vforks, 699 pages, average 43.69
2485 __tforks, 0 pages, average 0.00
49 kthread creations, 0 pages, average 0.00

end:
wiz# vmstat -f
4350 forks, 104204 pages, average 23.95
18 vforks, 709 pages, average 39.39
2568 __tforks, 0 pages, average 0.00
49 kthread creations, 0 pages, average 0.00


I'm guessing that for my usage profile I can go with an optimization
like this:
> sysctl kern.shminfo.shmmax=524288

Any more feedback?


== Daniele Bonini