| From: | Andres Freund <andres(at)anarazel(dot)de> |
|---|---|
| To: | Jonathon Nelson <jdnelson(at)dyn(dot)com> |
| Cc: | pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: [PATCH] guc-ify the formerly hard-coded MAX_SEND_SIZE to max_wal_send |
| Date: | 2017-01-05 19:01:19 |
| Message-ID: | 20170105190119.oe4gtbknbv2637fv@alap3.anarazel.de |
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| Thread: | |
| Lists: | pgsql-hackers |
Hi,
On 2017-01-05 12:55:44 -0600, Jonathon Nelson wrote:
> Attached please find a patch for PostgreSQL 9.4 which changes the maximum
> amount of data that the wal sender will send at any point in time from the
> hard-coded value of 128KiB to a user-controllable value up to 16MiB. It has
> been primarily tested under 9.4 but there has been some testing with 9.5.
>
> In our lab environment and with a 16MiB setting, we saw substantially
> better network utilization (almost 2x!), primarily over high bandwidth
> delay product links.
That's a bit odd - shouldn't the OS network stack take care of this in
both cases? I mean either is too big for TCP packets (including jumbo
frames). What type of OS and network is involved here?
Greetings,
Andres Freund
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