db2ckpwd uses a lot of memory
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From: danfan46 on 4 Aug 2008 05:33 Hi! I'm on Linux RHEL 64-bit db2 version 9.5.0.1 using four partitions on a single server. The db2ckpwd 4*3 =12 processes each uses 959220 k of memory which totals +10GB. Also the four db2wdog processes each uses +1GB Are these figures normal? Can they be configured? /dg
From: Darin McBride on 4 Aug 2008 16:26 danfan46(a)hotmail.com wrote: > Hi! > > I'm on Linux RHEL 64-bit db2 version 9.5.0.1 using four partitions on > a single server. > The db2ckpwd 4*3 =12 processes each uses 959220 k of memory which > totals +10GB. > Also the four db2wdog processes each uses +1GB > Are these figures normal? Where are you getting that information from? From what I can tell, each of my db2ckpwd processes are actually using under 30MB. Perhaps you're confusing VmSize and VmRSS? The VmSize is a virtual size - it just tells you how many pages are available to the process. That doesn't mean there is any real memory (either physical RAM or virtual through your swap partition(s)) behind it. The VmRSS tells you how much actual memory is allocated to the process (not swapped). Stolen from http://www.linuxforums.org/forum/linux-kernel/49438-proc-pid-status.html : VmSize: The size of the virtual memory allocated to the process VmLck: The amount of locked memory VmRSS: The amount of memory mapped in RAM ( instead of swapped out ) VmData: The size of the Data segment VmStk: The stack size VmExe: The size of the executable segment VmLib: The size of the library code VmPTE: Size of the Page Table entry I believe that shared memory gets counted in here. For example, the library code is unlikely to be duplicated from process to process - if you already have libdb2.so.1 loaded in one db2ckpwd process, it's unlikely to be copied to the other two. Instead, each process gets read-access to the same pages of memory, and thus it's only loaded once. Same goes for the data segment - much of it is likely shared in copy-on-write fashion (and most of it is unlikely to be written to). Some of it may be shared memory that is shared with db2syscr (the root-based system controller), so it's allocated either way anyway. > Can they be configured? You can try the disabling trick - but you should check your memory usage (I use conky for this) before and after to see if you're really seeing a memory savings. My bet is that you won't even notice.
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