hostap_80211_rx_status

Jouni Malinen jkmaline at cc.hut.fi
Mon Jul 19 22:13:45 EDT 2004


On Mon, Jul 19, 2004 at 04:51:45PM -0400, Sameer Moidu wrote:

> the fields in hostap_80211_rx_status include an unsigned-8bit for
> signal and noise. what are these values given as? Is there some easy
> way to convert between them and dBm?

They depend on hardware and firmware.. I'm not aware of any easy way to
convert to dBm in a way that would work reliably on all cards. The only
way to get a good conversion might be to calibrate this for the
particular card you are using..

> What is meaning of the jiffies
> variable that is used throughout the driver?

It's a kind of time stamp from Linux kernel. Timer interrupt handler
increases it by one (usually, 100 or 1000 times a second).

> Currently, I'm outputthing the signal, noise, rate, length and jiffies
> using printk(KERN_DEBUG at every call to hostap_80211_rx. I can
> understand that this introduces a lot of extra work for the kernel,
> but assumming I'm only running a simple udp transfer program and a
> capture for the log produced, will my network performance be adversely
> affected so as to give unrealistic data? Is there a more efficient way
> for me to extract this data from the driver?

How do you define "network performance"? If you care about latency or
throughput, using printk for each received packet is not very good idea.
Unfortunately, doing this in more reasonable way would require quite a
bit of changes to both the driver and Linux net stack.

-- 
Jouni Malinen                                            PGP id EFC895FA



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