* High UNIX socket latency
@ 2001-11-13 11:51 Jakob Østergaard
2001-11-14 0:27 ` GOTO Masanori
0 siblings, 1 reply; 2+ messages in thread
From: Jakob Østergaard @ 2001-11-13 11:51 UTC (permalink / raw)
To: linux-kernel
Hello all,
One program that creates a pipe between two processes and measures
the ping/pong latency of messages between the two processes gives
me something like;
1000 iterations - ping/pong time
max = 3495 us
min = 6 us
avg = 47.212 us
In another application where I use a UNIX STREAM socket, I get
a typical latency of one send() of around 1 ms.
I cannot set TCP_NODELAY on a UNIX socket, and I can't really
see why I get the high latency. Is there some undocumented
option like TCP_NODELAY for UNIX STREAM connections, or are there
other tricks I can play to get the latency down ?
One process does a send(), the other one does a select() and a
recv() - and the time from the send() to the recv() is around 1 ms
which I think seems far too high.
Hints, suggestions ?
Thank you
--
................................................................
: jakob@unthought.net : And I see the elder races, :
:.........................: putrid forms of man :
: Jakob Østergaard : See him rise and claim the earth, :
: OZ9ABN : his downfall is at hand. :
:.........................:............{Konkhra}...............:
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: High UNIX socket latency
2001-11-13 11:51 High UNIX socket latency Jakob Østergaard
@ 2001-11-14 0:27 ` GOTO Masanori
0 siblings, 0 replies; 2+ messages in thread
From: GOTO Masanori @ 2001-11-14 0:27 UTC (permalink / raw)
To: jakob, linux-kernel
At Tue, 13 Nov 2001 12:51:26 +0100,
Jakob Ostergaard <jakob@unthought.net> wrote:
> In another application where I use a UNIX STREAM socket, I get
> a typical latency of one send() of around 1 ms.
>
> I cannot set TCP_NODELAY on a UNIX socket, and I can't really
> see why I get the high latency. Is there some undocumented
> option like TCP_NODELAY for UNIX STREAM connections, or are there
> other tricks I can play to get the latency down ?
>
> One process does a send(), the other one does a select() and a
> recv() - and the time from the send() to the recv() is around 1 ms
> which I think seems far too high.
I think more details are needed... kernel version, packet size,
select timeout, your program/environment, the result of
average responce time and each responce time, throughput, etc.
-- gotom
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