Updating our TCP and socket sysctl values...

b. f. bf1783 at googlemail.com
Thu Aug 25 15:53:02 UTC 2011

> >> I believe it's time to up these values to something that's in line with higher speed
> >> local networks, such as 10G.  Perhaps it's time to move these to 2MB instead of 256K.
> >>
> >> Thoughts?
> >
> >
> > This never happened, did it?  Was there a reason?
> >
> I went back and looked at the mail thread.  I didn't see any strong objections
> so I think you should commit this for 9.x.
> np@ did point out that nmbclusters also lags on modern hardware so consider upping
> that at the same time.

I thought Bruce's observation, in:



"...there is an mostly-unrelated bufferbloat problem that is
purely local.  If you have a buffer that is larger than an Ln cache (or
about half than), then actually using just a single buffer of that size
guarantees thrashing of the Ln cache, so that almost every memory access
is an Ln cache miss.  Even with current hardware, a buffer of size 256K
will thrash most L1 caches and a buffer of size a few MB will thrash most
L2 caches."

, and his suggestion for some sort of auto-tuning, deserve
consideration.  Are you going to address this problem (at least the L2
and higher cache thrashing), or give some suggestions for tuning in
UPDATING and the relevant manpages?


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