Re: paging help is needed

From: hopehope_123 (hopehope_123_at_yahoo.com)
Date: 07/25/05

  • Next message: Tom: "Re: Modem dial IN" 
    Date: 24 Jul 2005 23:36:18 -0700

    Hi Tommy ,

    Thanks for your help . I have run the code :

    [oracle@tanidw1 tolga]$ ./pagetest
    page=16384 bytes.

    My page size is 16 KB.

    -However, as hinted in the "man 2 open" documentation, your buffer
    -must obey certain size and alignment constraints. This is necessary
    -because the virtual memory page containing your data buffer will be
    -treated the same as a page from the kernel buffer cache.

    In this case , with 16kb. page size , how can i understand whether
    alignment is a problem?

    I have also checked sar -W and vmstat outputs for both paging and
    swapping . The trend is after heavy paging activity the system starts
    swapping , than again paging. What vmstat shows is there exists 15-30
    process in blocked state , and at t he same time iostat shows disks
    are 100% utilized.

    The main application is oracle database server( this is a datawarehouse
    system with 2tb. data) and oracle paralallel query is mostly used.
    Since oracle parallel query bypasses the oracle buffer cache , data is
    stored inside the private memory region of each oracle process. If the
    system does not use direct io , does this mean that i double buffer the
    disk blocks ? (one for kernel - one for process )

    Kind Regards,
    hope

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