On Wed, 14 Feb 2001, Tom Sightler wrote:
> Quoting "Gord R. Lamb" <[EMAIL PROTECTED]>:
>
> > On Wed, 14 Feb 2001, Jeremy Jackson wrote:
> >
> > > "Gord R. Lamb" wrote:
> > > > in etherchannel bond, running
> > linux-2.4.1+smptimers+zero-copy+lowlatency)
>
> Not related to network, but why would you have lowlatency patches on
> this box?
Well, I figured it might reduce deadweight time between the different
operations (disk reads, cache operations, network I/O) at the expense of a
little throughput. It was just a hunch and I don't fully understand the
internals (of any of this, really). Since I wasn't saturating the disk or
network controller, I thought the gain from quicker response time (for
packet acknowledgement, etc.) would outweigh the loss of individual
throughputs. Again, I could be misunderstanding this completely. :)
> My testing showed that the lowlatency patches abosolutely destroy a
> system thoughput under heavy disk IO. Sure, the box stays nice and
> responsive, but something has to give. On a file server I'll trade
> console responsivness for IO performance any day (might choose the
> opposite on my laptop).
Well, I backed out that particular patch, and it didn't seem to make much
of a difference either way. I'll look at it in more detail tomorrow
though.
Cya.
> My testing wasn't very complete, but heavy dbench and multiple
> simultaneous file copies both showed significantly lower performance
> with lowlatency enabled, and returned to normal when disabled.
>
> Of course you may have had lowlatency disabled via sysctl but I was
> mainly curious if your results were different.
>
> Later,
> Tom
>
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