Thread (6 messages) 6 messages, 3 authors, 2008-07-19

Re: [RFC] RTT metrics scaling

From: Stephen Hemminger <hidden>
Date: 2008-06-28 05:30:20

On Fri, 27 Jun 2008 19:50:13 -0700 (PDT)
David Miller [off-list ref] wrote:
From: Stephen Hemminger <redacted>
Date: Fri, 20 Jun 2008 16:22:34 -0700
quoted
Some of the metrics (RTT, RTTVAR and RTAX_RTO_MIN) are stored in kernel
units (jiffies) and this leaks out through the netlink API to user space
where the units for jiffies are unknown.

This patches changes the kernel to convert to/from milliseconds. This changes
the ABI, but milliseconds seemed like the most natural unit for these parameters.

This patch is for comment only, just to show how it would be implemented.
I will update it after testing more.
No real objection.

But aren't we approaching microsecond RTT's soon? :-) (yes, I know in
TCP we min clamp at 200ms RTT, but that clamp we probably want to
remove soon)
We could put in microseconds, but since it is computer off of jiffies (ie clock
ticks), the resolution wouldn't be worth it.

If you don't think that's worth worrying about, I'll apply this patch.
Hold off it needs more testing.
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