[httperf] reply response time

Sylvain Geneves sylvain.geneves at inrialpes.fr
Fri Jun 10 06:44:17 PDT 2011


Thanks for your recommendation, Martin!

indeed it has proven usefull to collect a trace of the packets : I see between 60 and 90 micro-seconds between requests and responses, so it's not surprising that the response time is rounded up to 100 micro-seconds (0.1 ms) in httperf.

I still think that it is pretty fast (200K cycles between first byte of the request until first byte of the response is not much), but since I can see the response time increase along with the connection rate i'm happy.

Sorry for the noise, and thanks for your help.
Sylvain

----- Mail original -----
> De: "Martin Arlitt" <martin.arlitt at hp.com>
> À: "Sylvain Geneves" <sylvain.geneves at inrialpes.fr>, httperf at linux.hpl.hp.com
> Envoyé: Vendredi 10 Juin 2011 10:27:39
> Objet: RE: [httperf] reply response time
> Hi Sylvain
> 
> My recommendation is to collect a packet trace, then look at the
> response and transfer times for individual connections. If you still
> think there is a problem, then send the trace and the httperf output
> back to the list. You'll probably want to run a smaller test than the
> one below though.
> 
> Thanks
> Martin
> 
> 
> > -----Original Message-----
> > From: httperf-bounces at linux.hpl.hp.com [mailto:httperf-
> > bounces at linux.hpl.hp.com] On Behalf Of Sylvain Geneves
> > Sent: Friday, June 10, 2011 1:06 AM
> > To: httperf at linux.hpl.hp.com
> > Subject: [httperf] reply response time
> >
> > Hi,
> >
> > I run httperf tests on multiple machines with no apparent problem.
> > The
> > throughput seems fine and the server behaves as expected when the
> > rate
> > increase.
> > But when it comes to analyse response times, I've got a problem : at
> > low rate
> > (from 10 to 30) some client nodes httperf show response and transfer
> > times
> > below 1msec, like this :
> >
> > Reply time [ms]: response 0.1 transfer 0.1
> >
> >
> > I run my tests on a cluster over a LAN, where each node have 3 NICS
> > : 2
> > ethernet 1Gbps, and 1 Myrinet 10Gbps emulating ethernet.
> > All these NICS are connected through switches, so my question is :
> > how is
> > that possible ?
> >
> >
> > If someone has some insight, I would really appreciate it.
> > Best regards,
> > Sylvain
> >
> >
> >
> >
> > for further details, here is the output of one of the clients :
> >
> >
> > Total: connections 9074 requests 66532 replies 66532 test-duration
> > 471.350 s
> >
> > Connection rate: 19.3 conn/s (51.9 ms/conn, <=192 concurrent
> > connections)
> > Connection time [ms]: min 0.2 avg 8070.0 max 18122.8 median 7721.5
> > stddev
> > 6129.8 Connection time [ms]: connect 0.2 Connection length
> > [replies/conn]:
> > 7.332
> >
> > Request rate: 141.2 req/s (7.1 ms/req)
> > Request size [B]: 104.0
> >
> > Reply rate [replies/s]: min 7.6 avg 141.6 max 163.8 stddev 22.9 (94
> > samples)
> > Reply time [ms]: response 0.1 transfer 0.1 Reply size [B]: header
> > 63.0 content
> > 14609.0 footer 0.0 (total 14672.0) Reply status: 1xx=0 2xx=66532
> > 3xx=0 4xx=0
> > 5xx=0
> >
> > CPU time [s]: user 122.56 system 347.76 (user 26.0% system 73.8%
> > total
> > 99.8%) Net I/O: 2037.0 KB/s (16.7*10^6 bps)
> >
> > Errors: total 0 client-timo 0 socket-timo 0 connrefused 0 connreset
> > 0
> > Errors: fd-unavail 0 einval 0 addrunavail 0 ftab-full 0 other 0
> > Timeouts: total 0 class0=0 class1=0 class2=0 class3=0 class4=0
> > class5=0
> > class6=0 class7=0 class8=0 class9=0
> >
> > Session rate [sess/s]: min 4.20 avg 19.25 max 24.60 stddev 3.17
> > (9074/9074)
> > Session: avg 1.00 connections/session
> > Session lifetime [s]: 8.1
> > Session failtime [s]: 0.0
> > Session length histogram: 0 2676 0 0 0 571 587 625 557 592 606 556
> > 557 585 575
> > 587 _______________________________________________
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