You might consider a manual 'swapoff' (then 'swapon') of one large swap volume after that crunch time. In any case, this is one where you should reconsider how much VDISK to use. Obviously, there's a lot happening when it gets that end-of-month workload, so remember to include CPU and other I/O when you profile this server.
As Rob said, there's no page migration in Linux. (Other than to force the issue with a 'swapoff' and 'swapon' cycle.) So what you're seeing is random pages which got pushed out at various times during the stress period. If not needed, they will sit there forever. I like to differentiate between "swap occupancy" and "swap movement". The occupancy doesn't really hurt you in terms of response time. -- R; <>< Rick Troth Velocity Software http://www.velocitysoftware.com/ On Wed, Nov 2, 2011 at 10:21, Bauer, Bobby (NIH/CIT) [E] <baue...@mail.nih.gov> wrote: > Yes, having 4 is a little odd. We are struggling with this server. It sits > almost idle most of the month then for 1 or 2 days it gets 60 to 80 thousand > hits/hour. > Not sure what to make of this current display of the swap space. > > Bobby Bauer > Center for Information Technology > National Institutes of Health > Bethesda, MD 20892-5628 > 301-594-7474 > > > > -----Original Message----- > From: RPN01 [mailto:nix.rob...@mayo.edu] > Sent: Wednesday, November 02, 2011 10:14 AM > To: LINUX-390@VM.MARIST.EDU > Subject: Re: Odd swap space behavior > > That's what you want when you're using "spindles", but on z, you're usually > talking about v-disks, which are really virtual disks in memory. When > they're not in use, they take up no space at all, but when you start using > them, they start to occupy real memory and become a burden. So you set > priorities on the swap spaces so that they each get used one at a time in > turn. > > Ideally, you don't want to use them at all; they're a safeguard to keep the > image from coming down. When they are used, they're an indication that you > need more memory allocated to the image, and they give you a buffer to get > to the moment when you can safely cycle the image to add that memory. Having > four swap spaces allocated seems like a bit of overkill to me. It should be > sufficient to have one to be the buffer, and a second larger one to be the > trigger to increase the size of the image. > > -- > Robert P. Nix Mayo Foundation .~. > RO-OC-1-18 200 First Street SW /V\ > 507-284-0844 Rochester, MN 55905 /( )\ > ----- ^^-^^ > "In theory, theory and practice are the same, but > in practice, theory and practice are different." > > > > On 11/2/11 8:25 AM, "Richard Higson" <richard.hig...@gt.owl.de> wrote: > >> On Wed, Nov 02, 2011 at 07:37:17AM -0400, Bauer, Bobby (NIH/CIT) [E] wrote: > >> haven't done Linux on Z for a while, but I have always used the same >> "Priority" for the swapdisks >> so that linux could spread out the IO to several disks (preferably on >> separate >> spindles). >> This works well on x86 (real & VMware) and P-Series >> > > ---------------------------------------------------------------------- > For LINUX-390 subscribe / signoff / archive access instructions, > send email to lists...@vm.marist.edu with the message: INFO LINUX-390 or visit > http://www.marist.edu/htbin/wlvindex?LINUX-390 > ---------------------------------------------------------------------- > For more information on Linux on System z, visit > http://wiki.linuxvm.org/ > > ---------------------------------------------------------------------- > For LINUX-390 subscribe / signoff / archive access instructions, > send email to lists...@vm.marist.edu with the message: INFO LINUX-390 or visit > http://www.marist.edu/htbin/wlvindex?LINUX-390 > ---------------------------------------------------------------------- > For more information on Linux on System z, visit > http://wiki.linuxvm.org/ > ---------------------------------------------------------------------- For LINUX-390 subscribe / signoff / archive access instructions, send email to lists...@vm.marist.edu with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390 ---------------------------------------------------------------------- For more information on Linux on System z, visit http://wiki.linuxvm.org/
