Re: how to measure scheduler latency on powerpc? realfeel doesn't work due to /dev/rtc issues

Chris Friesen (cfriesen@nortelnetworks.com)
Thu, 08 May 2003 23:52:29 -0400

Richard B. Johnson wrote:
> On Thu, 8 May 2003, William Lee Irwin III wrote:
>>>>Why would you want to use an interrupt? Just count jiffies in sched.c

I'm trying to get a feel for the maximum time from an interrupt coming in until
the userspace handler gets notified. On intel you can program the hardware to
generate interupts through /dev/rtc. The powerpc doesn't seem to support this.

Jiffies are not accurate enough, I am expecting max latencies in the 1-2 ms range.

> Does it have a printer port like the Intel machines?

Unfortunately no. USB/Firewire/Ethernet on the desktop, ethernet/serial for
compactPCI.

I want to find an additional programmable interrupt source. It bites that cheap
PCs have this, and the powerpc doesn't.

Chris

-- 
Chris Friesen                    | MailStop: 043/33/F10
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