On 2019-07-27 19:10:22 -0400, Tom Lane wrote: > Andres Freund <and...@anarazel.de> writes: > > On 2019-07-27 18:34:50 -0400, Tom Lane wrote: > >> Yeah. The existing commentary about that is basically justifying 8K > >> as being large enough to avoid performance issues; if somebody can > >> show that that's not true, I wouldn't have any hesitation about > >> kicking it up. > > > You think that unnecessary fragmentation, which I did show, isn't good > > enough? That does have cost on the network level, even if it possibly > > doesn't show up that much in timing. > > I think it is worth doing some testing, rather than just blindly changing > buffer size, because we don't know how much we'd have to change it to > have any useful effect.
I did a little test with nttcp between two of our servers (1 Gbit to
different switches, switches connected by 10 Gbit). The difference
between a 1024 byte buffer and a 1460 byte buffer is small but
measurable. Anything larger doesn't make a difference. So increasing the
buffer beyond 8 kB probably doesn't improve performance on a 1 Gbit LAN.
I didn't test 10 Gbit LAN or WAN - those might be different.
hp
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_ | Peter J. Holzer | we build much bigger, better disasters now
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