Please whitelist cPanel in your adblocker so that you’re able to see our version release promotions, thanks!

The Community Forums

Interact with an entire community of cPanel & WHM users!

baseline/optimal pigz block size (chunks per compression unit)

Discussion in 'Workarounds and Optimization' started by ottdev, Mar 27, 2018.

  1. ottdev

    ottdev Well-Known Member

    Oct 1, 2013
    Likes Received:
    Trophy Points:
    cPanel Access Level:
    Root Administrator
    Some guidance please ??
    with regards to chunks per compression work units - which I gather alters pigz' -b (block size) parameter.

    Is there a calculation based on system memory that gives you a good number to start with?
    The default is way up at 4096. I recently attempted to change the value in a VPS from 128 to 1024 and this caused backups times to more than quadruple and cause way higher server loads. Obviously not optimal to have backups now dragging into morning work hours. So I will set this one back.

    Is there a rule of thumb?
    Couldn't find any useful info in cpanel or pigz docs.

    And why is it that pigz docs say default is 128, and cpanel has chosen 4096 as the default? <= how did that figure come to be chosen?
  2. cPanelMichael

    cPanelMichael Technical Support Community Manager Staff Member

    Apr 11, 2011
    Likes Received:
    Trophy Points:
    cPanel Access Level:
    Root Administrator

    As I understand, using a higher value for the "Number of kilobyte chunks per compression work unit" option will benefit systems with larger L2/L3 caches. There's no specific rule of thumb or guidelines to follow, however here's a third-party URL on L2/L3 cache sizes you may find helpful:

    L2 Vs. L3 CPU cache speed and performance

    Fine tuning the value often occurs through testing, and can depend on your specific system's existing performance and hardware specifications. It's generally something that a qualified system administrator would need to adjust:

    System Administration Services | cPanel Forums

    As far as the current default of 4096, it's the value that was found to offer the best performance across the widest variety of testing environments.

    Thank you.
    Stop hovering to collapse... Click to collapse... Hover to expand... Click to expand...

Share This Page

  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.
    Dismiss Notice