Re: [tcpm] TCP tuning

[Joe Touch <[e-mail]>]

Did you use a netperf option to disable Nagle?

There are also many reasons this could happen; it might be easier to see
in a plot.

Joe

rick jones wrote:
> 
> On Feb 3, 2010, at 9:41 PM, rick jones wrote:
>> PS - I suppose if I'd been thinking more clearly, I'd have also
>> included --enable-historgram in the ./configure command and been able
>> to give a histogram of the response times (adding a -v 2 option to the
>> global command line options), but I suppose that can be guesstimated
>> from the traces.
> 
> Ok, so perhaps I like running netperf too much :)  Here then are the
> application-level measured response times.  The first netperf is with
> tcp_slow_start_after_idle = 0, the second with it set to 1, I'll
> leave-out the rest of the netperf output as it is repetitive:
> 
> tcp_slow_start_after_idle = 0 on server:
> 
> Histogram of request/response times
> UNIT_USEC     :    0:    0:    0:    0:    0:    0:    0:    0:    0:    0
> TEN_USEC      :    0:    0:    0:    0:    0:    0:    0:    0:    0:    0
> HUNDRED_USEC  :    0:    0:    0:    0:    0:    0:    0:    0:    0:    0
> UNIT_MSEC     :    0:    0:    0:    0:    0:    0:    0:    0:    0:    0
> TEN_MSEC      :    0:    0:    0:    0:    0:    0:    0:    0:    0:    0
> HUNDRED_MSEC  :    0:  294:    4:    0:    2:    0:    0:    0:    0:    0
> UNIT_SEC      :    0:    0:    0:    0:    0:    0:    0:    0:    0:    0
> TEN_SEC       :    0:    0:    0:    0:    0:    0:    0:    0:    0:    0
>>100_SECS: 0
> HIST_TOTAL:      300
> 
> That means 294 times 100ms <= responsetime < 200ms, 4 times it was 200ms
> <= responsetime < 300ms etc etc.
> 
> tcp_slow_start_after_idle = 1 on server:
> 
> UNIT_USEC     :    0:    0:    0:    0:    0:    0:    0:    0:    0:    0
> TEN_USEC      :    0:    0:    0:    0:    0:    0:    0:    0:    0:    0
> HUNDRED_USEC  :    0:    0:    0:    0:    0:    0:    0:    0:    0:    0
> UNIT_MSEC     :    0:    0:    0:    0:    0:    0:    0:    0:    0:    0
> TEN_MSEC      :    0:    0:    0:    0:    0:    0:    0:    0:    0:    0
> HUNDRED_MSEC  :    0:    0:    0:  290:   10:    0:    0:    0:    0:    0
> UNIT_SEC      :    0:    0:    0:    0:    0:    0:    0:    0:    0:    0
> TEN_SEC       :    0:    0:    0:    0:    0:    0:    0:    0:    0:    0
>>100_SECS: 0
> HIST_TOTAL:      300
> 
> Now it was 290 with 300ms <= responsetime < 400ms
> 
> Just as a refresher, the request size was 128 bytes, the response size
> 16384.
> 
> The ICMP Echo RTT is ~120 ms between my home system and netperf.org:
> 
> --- netperf.org ping statistics ---
> 10 packets transmitted, 10 packets received, 0% packet loss
> round-trip min/avg/max/stddev = 119.523/120.410/121.248/0.493 ms
> 
> rick jones
> Wisdom teeth are impacted, people are affected by the effects of events