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Slow network performance with virtualization

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Slow network performance with virtualization

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Customer moves their databases from CentOS 6 to CentOS 7 (3.10.0-957.27.2). Both are VMWare on the same metal box. Network driver vmxnet3
Performance dropped down approximately by 9 times

Test against the sports2000 database:

ETIME(TRUE).
FOR EACH OrderLine NO-LOCK /*NO-PREFETCH*/ /* SHARE-LOCK */ :
  ACCUMULATE "rec":U (COUNT).
END.
MESSAGE ETIME VIEW-AS ALERT-BOX.

Table OrderLine has 13970 records.

Results:

CentOS 6

Run  NO-LOCK NO-PREFETCH SHARE-LOCK
1       79      1353     1736
2       75      1364     1624
3       80      1368     2049
4       80      1328     1729
5       93      1508     1683
6       79      1368     2015
7       99      1550     1730
8       73      3714     1924
9       93      1643     1668
10      90      1426     1679
11      87      1392     1809
AVE    84.4     1637.6   1786.0

CentOS 7

Run  NO-LOCK NO-PREFETCH SHARE-LOCK
1       88      7137     26541
2      102      6281     26013
3       87      7259     25303
4       82      7381     25318
5       88      6883     27381
6       84      6472     27532
7       79      6101     25775
8       87      5960     27045
9       82      6029     25494
10     111      4909     26087
11      80      6284     26263
AVE     88.2    6426.9   26250.2

Results on CentOS 6 are expected:
NO-LOCK is 20 times faster than NO-LOCK NO-PREFETCH (-Mm 16384): a few messages vs. one tiny record (43 bytes in average) per network message;
SHARE-LOCK is just a bit slower than NO-LOCK NO-PREFETCH. It’s still one record per network message.

Results on CentOS 7:
NO-LOCK is as fast as on CentOS 6;
NO-LOCK NO-PREFETCH is 3.92 times slower than the same code on CentOS 6;
SHARE-LOCK is 4.08 times slower than NO-LOCK NO-PREFETCH.


Note: the factor 4 in both two unexpected cases.

It was suggested to run ‘rngd -r /dev/urandom’ but the customer can’t find the rngd on both CentOS.

What is the root case of the slowness?
How to solve the issue?

All Replies
  • Make sure you are running latest VMTools.
    Also double check if the NIC is defined as passthru.

    Sent from my iPhone

    On 11 Oct 2019, at 18:23, George Potemkin <bounce-GeorgeP12@community.progress.com> wrote:

    <ProgressEmailLogo-png_2D00_150x42x2-png> Update from Progress Community
    <4U3VBQTP4GDL-jpg_2D00_70x70x2-jpg>
    George Potemkin

    Customer moves their databases from CentOS 6 to CentOS 7 (3.10.0-957.27.2). Both are VMWare on the same metal box. Network driver vmxnet3
    Performance dropped down approximately by 9 times

    Test on sports2000 database:

    ETIME(TRUE).
    FOR EACH OrderLine NO-LOCK /*NO-PREFETCH*/ /* SHARE-LOCK */ :
      ACCUMULATE "rec":U (COUNT).
    END.
    MESSAGE ETIME VIEW-AS ALERT-BOX.

    Table OrderLine has 13970 records.

    Results:

    Centos 6

    Run  NO-LOCK NO-PREFETCH SHARE-LOCK
    1       79      1353     1736
    2       75      1364     1624
    3       80      1368     2049
    4       80      1328     1729
    5       93      1508     1683
    6       79      1368     2015
    7       99      1550     1730
    8       73      3714     1924
    9       93      1643     1668
    10      90      1426     1679
    11      87      1392     1809
    AVE    84.4     1637.6   1786.0

    Centos 7

    Run  NO-LOCK NO-PREFETCH SHARE-LOCK
    1       88      7137     26541
    2      102      6281     26013
    3       87      7259     25303
    4       82      7381     25318
    5       88      6883     27381
    6       84      6472     27532
    7       79      6101     25775
    8       87      5960     27045
    9       82      6029     25494
    10     111      4909     26087
    11      80      6284     26263
    AVE     88.2    6426.9   26250.2

    Results on Centos 6 are expected:
    NO-LOCK is 20 times faster than NO-LOCK NO-PREFETCH (-Mm 16384): a few messages vs. one tiny record (43 bytes in average) per network message;
    SHARE-LOCK is just a bit slower than NO-LOCK NO-PREFETCH. It’s still one record per network message.

    Results on Centos 7:
    NO-LOCK is as fast as on Centos 6;
    NO-LOCK NO-PREFETCH is 3.92 times slower than the same code on Centos 6;
    SHARE-LOCK is 4.08 times slower than NO-LOCK NO-PREFETCH.


    Note: the factor 4 in both two unexpected cases.

    It was suggested to run ‘rngd -r /dev/urandom’ but the customer can’t find the rngd on both CentOS.

    What is the root case of the slowness?
    How to solve the issue?

    View online

     

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  • Thanks, Libor!

  • Customer installed the old version Centos 7 (2015 year) and network performance was fine (30-35Gib/s according to  iperf). Then he updated OS to the recent version (using 'yum update') and performance dropped down to 12-15 Gib/s. So some of the updates of Centos 7 has an issue.