On Tue, 16 Apr 2013, Sepherosa Ziehau wrote:
On Tue, Apr 16, 2013 at 3:14 PM, Bruce Evans <b...@optusnet.com.au> wrote:
bge_rx_coal_ticks == 0 && bge_rx_max_coal_bds == 0 might work accidentally
if there are enough tx interrupts. There is also the DEVICE_POLLING
mistake.
In polling mode, these parameters of course have no effect (Polling mode
disables interrupts, and the coal parameters have no effect when interrupts
are disabled).
As far as I have tested, coalesce BDs and ticks also control how often
status block is updated, so it does affect polling(4)
This might explain why polling worked even worse than expected for most
things. However, I got reduced latency using it (from ~55 usec ping
latency to ~30 usec). 30 usec would be impossible with the default
parameters (normal is an average of at least half of bge_rx_coal_ticks).
Maybe I had the parameters reduced to bge_rx_coal_bds = 1 when I found
30 usec (then bge_rx_coal_ticks doesn't matter). This is probably what
polling should use.
Bruce
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