Re: [Flent-users] [tohojo/flent] RRUL Upload plot - why such low granularity? (#185)

From: Sebastian Moeller <moeller0@gmx.de>
To: tohojo/flent
	<reply+AHVNJP5TBZ2RLAX6JBA647F3TYZ2NEVBNHHB3DQ34A@reply.github.com>
Cc: tohojo/flent <flent@noreply.github.com>,
	Comment <comment@noreply.github.com>,
	flent-users <flent-users@flent.org>
Subject: Re: [Flent-users] [tohojo/flent] RRUL Upload plot - why such low granularity? (#185)
Date: Sun, 29 Sep 2019 21:34:46 +0200	[thread overview]
Message-ID: <6D925525-6E60-4CCE-AD78-C472800F2331@gmx.de> (raw)
In-Reply-To: <tohojo/flent/issues/185/536331577@github.com>

Hi Toke,

> On Sep 29, 2019, at 21:08, Toke Høiland-Jørgensen <notifications@github.com> wrote:
> 
> flent-users <notifications@github.com> writes:
> 
> > Hi Toke,
> >
> >> On Sep 29, 2019, at 20:44, Toke Høiland-Jørgensen <notifications@github.com> wrote:
> >> 
> >> Rich Brown <notifications@github.com> writes:
> >> 
> >> > Sorry for the delay in responding... The higher granularity makes much
> >> > better plots (see below).
> >> 
> >> Great!
> >> 
> >> > Using `-m 2048,2048` I don't see a whole lot of load on my Mac 2.5 GHz
> >> > Intel Core i7 at 7mbps/768kbps. Thanks.
> >> 
> >> No, don't expect it would. The CPU usage thing will hit you at high
> >> rates (I was testing on a gigabit link).
> >> 
> >> I'm not sure we can realistically pick an option that works well for
> >> both slow and fast links. So we may have to add a switch; and then the
> >> problem becomes what to use for defaults...
> >
> > How about make it not a "switch" but a numeric parameter, and
> > default to the current default value by principle of least
> > surprise?
> 
> Well, by "switch" I just meant "new command line option".

	Oops, sorry, I read this as a switch to toggle between say the default (which seems system dependent not petperf dependent, no?) and a value for low bandwidth links, say 1460...

> The obvious
> form of that would be, as you say, just the ability to set the netperf
> xfer size directly...

	I guess that would be the best compromise, if the user knows about a links asymmetry the send and receive buffers can be sized accordingly like 16K, 1600 for DOCSIS down-/upload...

I also wonder whether flent should not try to also record and parse /proc/stat to detect CPU overload (so the user could be warned/informed to increase the xfer size if there is danger of being CPU bound)?

Best Regards
	Sebastian

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