Datafile buffering w/ OSF1

From: Antti Jarvinen <costello_at_iki.fi>
Date: 2000/05/08
Message-ID: <m33dnt15hg.fsf@cs72168.pp.htv.fi>#1/1

I'm having a slight swapping problem with digital unix 4.0 and oracle804: bash-2.02$ vmstat 1
Virtual Memory Statistics: (pagesize = 8192)

  procs    memory         pages                          intr        cpu

r w u act free wire fault cow zero react pin pout in sy cs us sy id 2141 33 12K 62 50K 782M 25M 212M 134M 67M 15M 158 1K 747 38 5 57 3141 32 12K 50 50K 1336 91 549 3321 252 70 387 1K 1K 26 16 58 4134 36 12K 42 50K 982 54 377 58 225 68 354 2K 1K 40 23 37 ...
and almost all processes (including ora*) are regularly swapped out and in causing pretty ugly slowdown.

I'm thinking this might be a file system buffering problem. Our application for most part does things periodically: there are processes that do things, then go to sleep() for some time, wake up and begin stressing the DB again. Every wakeup seems to cause swapping. Because this application does not use files, database is the storage for all necessary stuff then I'm not sure where the file access are coming from and therefore:

does 8.0.4.3.0 on 4.0d open datafiles in such a mode that the filesystem does not cache the datafile contents again?

As this uses datafiles in AdvFS-disks, no raw partitions are used.

Also, I wonder if it does any good to lock SGA into memory as it seems to be possible. It should prevent the system from swapping the SGA but then it would increase swapping of other processes? Vmstat -P shows the following breakdown from "wired" part of memory: WIRED Pages Break Down:

   vm wired pages = 1199
  ubc wired pages = 4652
  meta data pages = 1958
     malloc pages = 41320
     contig pages = 279
    user ptepages = 652
  kernel ptepages = 54
    free ptepages = 4

.. total system memory is only 64K pages then what the fsck is this "malloc pages" or how do I find out what is eating it? It is clearly not SGA as I see ora* -processes with good sized being swapped.

Thanks for your help,

-- 
Antti Järvinen, costello_at_iki.fi
            "concerto for two faggots and orchestra"

Received on Mon May 08 2000 - 00:00:00 CDT