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've been working as an Oracle database administrator and PeopleSoft administrator since 1994. I'm very interested in Oracle performance tuning.
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2 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.

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