HugePages speeds up Oracle login process on Linux

We bumped a Linux database up to a 12 gigabyte SGA and the login time went up to about 2.5 seconds. Then a Linux admin configured 12 gigabytes of HugePages to fit the SGA and login time went down to .13 seconds. Here is how I tested the login time. E.sql just has the exit command in it so this logs in as SYSDBA and immediately exits:

$ time sqlplus / as sysdba < e.sql

... edited out for space ...

real    0m0.137s
user    0m0.007s
sys     0m0.020s

So, then the question came up about our databases with 3 gig SGAs without HugePages. So I tested one of them:

real    0m0.822s
user    0m0.014s
sys     0m0.007s

Same version of Oracle/Linux/etc. Seems like even with a 3 gig SGA the page table creation is adding more than half a second to the login time. No wonder they came up with HugePages for Linux!


About Bobby

I live in Chandler, Arizona with my wife and three daughters. I work for US Foods, the second largest food distribution company in the United States. I have worked in the Information Technology field since 1989. I have a passion for Oracle database performance tuning because I enjoy challenging technical problems that require an understanding of computer science. I enjoy communicating with people about my work.
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3 Responses to HugePages speeds up Oracle login process on Linux

  1. jkstill says:

    Interesting observations, thank you Bobby.

    Thinking back a bit on my home lab, the login time sped up quite a bit when I finally got around to configuring HugePages on 11g/12c RAC.

    Until now I had not made the connection between HugePages and login times. Login times are now quite fast.

    time sqlplus jkstill/XXX@p1 <<EOF
    select sysdate from dual;

    real 0m0.080s
    user 0m0.000s
    sys 0m0.023s

    • Bobby says:

      Thanks for your comment Jared. I was surprised at how clear of a connection there was between HugePages and login time. I knew that HugePages was a good thing to do but did not realize that the benefit would be so visible.

  2. Pingback: Huge Pages Speeds Startup of Web Servers | Bobby Durrett's DBA Blog

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