Bug 118124 - [request] HZ value on slow computers should by dynamic
Summary: [request] HZ value on slow computers should by dynamic
Status: Open
Alias: None
Product: Base System
Classification: Unclassified
Component: kern (show other bugs)
Version: 6.2-STABLE
Hardware: Any Any
: Normal Affects Only Me
Assignee: freebsd-bugs (Nobody)
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2007-11-19 13:50 UTC by hsu
Modified: 2018-05-20 23:53 UTC (History)
0 users

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Description hsu 2007-11-19 13:50:01 UTC 
HZ was bumped to 1000 couple of years ago.  This is fine for quick computers,
but becomes a problem on old computers and various embedded devices.

On Vortex86 cpu at 200MHz, and HZ set to 1000, with DUMMYNET and IPFW built
into the kernel, cpu seems to spend around 12-14% of time in interrupt
and overall performance is really low.

Fix: 

HZ should probably be dynamic, based on cpu, rather than a fixed value
in kernel config. 

Workaround is setting HZ in loader.conf
How-To-Repeat: 
Install FreeBSD on a slow computer.  Try a 486, old pentiums, anything Sis550
or Geode based.  Use a kernel with all firewall, dummynet and other heavy
networking options on.
Comment 1 Mark Linimon freebsd_committer freebsd_triage 2008-01-28 09:21:23 UTC 
State Changed
From-To: open->suspended

Mark suspended awaiting patches.
Comment 2 Eitan Adler freebsd_committer freebsd_triage 2018-05-20 23:53:05 UTC 
For bugs matching the following conditions:
- Status == In Progress
- Assignee == "bugs@FreeBSD.org"
- Last Modified Year <= 2017

Do
- Set Status to "Open"