Max swap size ?

Max swap size ?

[Christopher Murtagh]

 Greetings,

 I have a machine running YDL (Dual 800Mhz, 1GB RAM) with a 2.4.13 SMP
kernel (YellowDog's stock SMP kernel) that has a 512 MB swap partition.
When I tried to install on other machines, they wouldn't boot with a swap
partition that big, but for some reason this one did. It wasn't until
after the other machines wouldn't boot did I notice in the TerraSoft docs
that 256MB was the max. The machine ran beautifully until today when it
did a nasty crash. My gut feeling is that it crashed when it tried to
write to the swap for the first time as it was inching up to using almost
all available RAM when it died.

 So my question is: Is this a likely cause and will resizing the swap
partition fix this or do I have bigger problems? Any info would be much
appreciated.

Cheers,

Chris

 P.S. Many thanks to all PPC Linux hackers. My servers and desktop
machines run beautifully because of your work. If any of you come to Mtl,
look me up and I'll take you out for a drink (Beer, coffe, etc.) and some
hospitality.

--

Christopher Murtagh
Webmaster / Sysadmin
Web Communications Group
McGill University
Montreal, Quebec
Canada

Tel.: (514) 398-3122
Fax:  (514) 398-2017


** Sent via the linuxppc-dev mail list. See http://lists.linuxppc.org/

Re: Max swap size ?

[Michel Dänzer]

On Tue, 2001-12-04 at 00:04, Christopher Murtagh wrote:

>  I have a machine running YDL (Dual 800Mhz, 1GB RAM) with a 2.4.13 SMP
> kernel (YellowDog's stock SMP kernel) that has a 512 MB swap partition.
> When I tried to install on other machines, they wouldn't boot with a swap
> partition that big, but for some reason this one did. It wasn't until
> after the other machines wouldn't boot did I notice in the TerraSoft docs
> that 256MB was the max.

That used to be the case before kernel 2.2 IIRC. Nowadays the limit is
in the gigabytes. FWIW I'm using a 400 meg swap partition without
problems.

> The machine ran beautifully until today when it did a nasty crash. My gut
> feeling is that it crashed when it tried to write to the swap for the
> first time as it was inching up to using almost all available RAM when
> it died.

Are you sure it only hit swap then? I can't remember ever seeing active
but completely unused swap space, even when RAM usage was low.


The bottom line is yes, you likely have another problem.


--
Earthling Michel Dänzer (MrCooper)/ Debian GNU/Linux (powerpc) developer
XFree86 and DRI project member   /  CS student, Free Software enthusiast

** Sent via the linuxppc-dev mail list. See http://lists.linuxppc.org/

Re: Max swap size ?

[Geert Uytterhoeven]

On 4 Dec 2001, Michel [ISO-8859-1] Dänzer wrote:
> On Tue, 2001-12-04 at 00:04, Christopher Murtagh wrote:
> >  I have a machine running YDL (Dual 800Mhz, 1GB RAM) with a 2.4.13 SMP
> > kernel (YellowDog's stock SMP kernel) that has a 512 MB swap partition.
> > When I tried to install on other machines, they wouldn't boot with a swap
> > partition that big, but for some reason this one did. It wasn't until
> > after the other machines wouldn't boot did I notice in the TerraSoft docs
> > that 256MB was the max.
>
> That used to be the case before kernel 2.2 IIRC. Nowadays the limit is
> in the gigabytes. FWIW I'm using a 400 meg swap partition without
> problems.

The limit used to be 128 MiB, not 256 MiB. They used one page as a bitmask to
mark swap pages that were in use, hence 4096*8*4kiB = 128 MiB.

Gr{oetje,eeting}s,

						Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
							    -- Linus Torvalds


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Re: Max swap size ?

[Christopher Murtagh]

 Thanks for the replies.

On 4 Dec 2001, Michel Dänzer wrote:
>That used to be the case before kernel 2.2 IIRC. Nowadays the limit is
>in the gigabytes. FWIW I'm using a 400 meg swap partition without
>problems.

 Ok, well that's good to hear.

>Are you sure it only hit swap then? I can't remember ever seeing active
>but completely unused swap space, even when RAM usage was low.
>
>The bottom line is yes, you likely have another problem.

 This isn't though.. :-(

Mem:  1024100K av,  774636K used,  249464K free,  0K shrd,  179708K  buff
Swap:  524280K av,       0K used,  524280K free             490400K  cached

 this is what my machine is like at the moment. So, from what you are
saying, my problem lies elsewhere (ie. is not swap *size*), but is likely
swap related? Is there a way I can force swapping in an elegant way to
test whether this will bring down my machine? Thanks again.

Cheers,

Chris


--

Christopher Murtagh
Webmaster / Sysadmin
Web Communications Group
McGill University
Montreal, Quebec
Canada

Tel.: (514) 398-3122
Fax:  (514) 398-2017


** Sent via the linuxppc-dev mail list. See http://lists.linuxppc.org/

Re: Max swap size ?

[Michel Dänzer]

On Tue, 2001-12-04 at 17:35, Christopher Murtagh wrote:
>
>  Thanks for the replies.
>
> On 4 Dec 2001, Michel Dänzer wrote:
> >That used to be the case before kernel 2.2 IIRC. Nowadays the limit is
> >in the gigabytes. FWIW I'm using a 400 meg swap partition without
> >problems.
>
>  Ok, well that's good to hear.
>
> >Are you sure it only hit swap then? I can't remember ever seeing active
> >but completely unused swap space, even when RAM usage was low.
> >
> >The bottom line is yes, you likely have another problem.
>
>  This isn't though.. :-(
>
> Mem:  1024100K av,  774636K used,  249464K free,  0K shrd,  179708K  buff
> Swap:  524280K av,       0K used,  524280K free             490400K  cached
>
>  this is what my machine is like at the moment. So, from what you are
> saying, my problem lies elsewhere (ie. is not swap *size*), but is likely
> swap related?

Or maybe it's related to the huge amount of RAM you have, but others
will know better.


--
Earthling Michel Dänzer (MrCooper)/ Debian GNU/Linux (powerpc) developer
XFree86 and DRI project member   /  CS student, Free Software enthusiast

** Sent via the linuxppc-dev mail list. See http://lists.linuxppc.org/