Any issue to be considered if ethernet send buffer is modified

Any issue to be considered if ethernet send buffer is modified

[Ashoka K]

Hi,

I use embedded system with 2.6.33, Preempt patch. To reduce the
latency of sending data by our application, the ethernet send buffer
is modified with setsockopt().

Before modification the send buffer size by default was shown as 16384 bytes.
But on proc system value shown is different, both default and max are same:
/proc/sys/net/core/wmem_default = 108544

Eventhough the above value is not modified, why the default is shown
as 16384 instead 108544. Did kernel change these values during sending
traffic ?

If send buffer is set by setsockopt(), is this value modified by
kernel during run time?

AK

Re: Any issue to be considered if ethernet send buffer is modified

[Sebastian Andrzej Siewior]

* Ashoka K | 2013-08-30 13:51:14 [+0530]:

>Hi,
Hi,

>I use embedded system with 2.6.33, Preempt patch. To reduce the
>latency of sending data by our application, the ethernet send buffer
>is modified with setsockopt().
>
>Before modification the send buffer size by default was shown as 16384 bytes.
>But on proc system value shown is different, both default and max are same:
>/proc/sys/net/core/wmem_default = 108544
>
>Eventhough the above value is not modified, why the default is shown
>as 16384 instead 108544. Did kernel change these values during sending
>traffic ?
>
>If send buffer is set by setsockopt(), is this value modified by
>kernel during run time?

Try to grep for sysctl_wmem_default. Atleast on v3.10 this value is
initialized at compile time and only updated via sysctl and not by the
kernel.

>AK

Sebastian
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