netdev - Re: TCP socket send return EAGAIN unexpectedly when sending small fragments

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Message-ID: <CAMJ=MEe3r+ZrAONTciQgU4yqtXTJJvXc0OFvJYwYg20kPGQtdA@mail.gmail.com>
Date:   Fri, 10 Jun 2022 19:16:06 +0200
From:   Ronny Meeus <ronny.meeus@...il.com>
To:     David Laight <David.Laight@...lab.com>
Cc:     Eric Dumazet <erdnetdev@...il.com>, netdev <netdev@...r.kernel.org>
Subject: Re: TCP socket send return EAGAIN unexpectedly when sending small fragments

Op vr 10 jun. 2022 om 17:21 schreef David Laight <David.Laight@...lab.com>:
>
> ...
> > If the 5 queued packets on the sending side would cause the EAGAIN
> > issue, the real question maybe is why the receiving side is not
> > sending the ACK within the 10ms while for earlier messages the ACK is
> > sent much sooner.
>
> Have you disabled Nagle (TCP_NODELAY) ?

Yes I enabled TCP_NODELAY so the Nagle algo is disabled.
I did a lot of tests over the last couple of days but if I remember well
enable or disable TCP_NODELAY does not influence the result.

> Nagle only really works for bulk data transfer (large sends)
> and interactive sessions (command - response).
> For nearly everything else it adds unwanted 100ms delays.
>
>         David
>
> -
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