Again thanks to everyone who responded............
Nick Hill was the first to respond with.......
round_robin_switch_rate
All to do with what old VMS people would call quantum. From a recent
discussion about how to vary this the summary was:
man sys_attrs_proc
Look for the parameter round_robin_switch_rate :
round_robin_switch_rate
A value that determines (per second of CPU time) the number of context
switches that can occur between processes with the same priority and
the timeslice allotted to each process.
Default value: 0 (100 context switches per second)
Minimum value: 0
Maximum value: hz
The system uses the following formula to compute timeslice:
timeslice = hz / number_context_switches
The hz value is the timer interrupt frequency (hertz) for one second
of
CPU time. This value is dependent on hardware and is typically 1024
or
1200. (To determine the hz value on a particular system, programmers
can use the getsysinfo() call with GSI_CLK_TCK as the op parameter.)
If round_robin_switch_rate is either 0 (zero) or greater than hz, the
system uses 100 for number_context_switches. For example, if hz is
1024, the resulting timeslice is 10 milliseconds, and if hz is 1200,
the resulting timeslice is 12 milliseconds:
timeslice = 1024 / 100 = 10
timeslice = 1200 / 100 = 12
If round_robin_switch_rate is greater than zero and less than or equal
to hz, then number_context_switches is set to round_robin_switch_rate.
For example, changing round_robin_switch_rate from 0 to 20 decreases
the number of context switches and increases timeslice by a factor of
five:
timeslice = 1024 / 20 = 51
timeslice = 1200 / 20 = 60
Context switching carries a certain amount of CPU overhead. If a CPU
consistently handles many large jobs that do not complete quickly, a
larger timeslice (and fewer context switches) may improve throughput.
However, the tradeoff is reduced response time for any interactive
processes that the CPU handles.
Cheers
AT
>>> Andrew Tolmie <Andrew.Tolmie_at_Carltonscreen.com> 07/12/01 10:20am >>>
Gang......
I know I still need to send in a couple of summaries, but they're gonna have to wait a little longer!
Can anybody tell me what the round_robin_switch_rate is?
I've trawled through the online docs and can't find it anywhere!?!
Cheers
AT
This e-mail and any attachment is confidential and may be legally privileged. It is intended for the named recipient only. If you have received it in error, please do not forward it or copy it or act upon its contents,
but report it to postmaster_at_carltonscreen.com
Any dissemination, distribution, copying or use of this communication without the permission of the addressee is prohibited.
The contents of an attachment to this e-mail may contain software viruses, which could damage your computer system or data. While Carlton Screen Advertising Ltd has taken reasonable precautions to prevent the inclusion of viruses in e-mails and attachments, neither it nor the sender can accept any liability for any loss or damage sustained as a result of software viruses. You are strongly advised to carry out your own virus checking before opening any attachments.
This e-mail and any attachment is confidential and may be legally privileged. It is intended for the named recipient only. If you have received it in error, please do not forward it or copy it or act upon its contents,
but report it to postmaster_at_carltonscreen.com
Any dissemination, distribution, copying or use of this communication without the permission of the addressee is prohibited.
The contents of an attachment to this e-mail may contain software viruses, which could damage your computer system or data. While Carlton Screen Advertising Ltd has taken reasonable precautions to prevent the inclusion of viruses in e-mails and attachments, neither it nor the sender can accept any liability for any loss or damage sustained as a result of software viruses. You are strongly advised to carry out your own virus checking before opening any attachments.
Received on Fri Jul 27 2001 - 12:52:22 NZST