R: [users@httpd] Apache throughput problem with high latency client (WAN) on Windows 2000
Solved, I needed to set SendBufferSize because on windows platform Apache
takes by default 4KB
This is documented in "listen.c"
* To send data over high bandwidth-delay connections at full
* speed we must force the TCP window to open wide enough to keep the
* pipe full. The default window size on many systems
* is only 4kB. Cross-country WAN connections of 100ms
* at 1Mb/s are not impossible for well connected sites.
* If we assume 100ms cross-country latency,
* a 4kB buffer limits throughput to 40kB/s.
* To avoid this problem I've added the SendBufferSize directive
* to allow the web master to configure send buffer size.
* The trade-off of larger buffers is that more kernel memory
* is consumed. YMMV, know your customers and your network!
* -John Heidemann <[hidden email]> 25-Oct-96
* If no size is specified, use the kernel default.
>Da: [hidden email] [mailto:[hidden email]]
>Inviato: mercoledì 27 aprile 2005 15.02
>A: [hidden email] >Oggetto: [users@httpd] Apache throughput problem with high
>latency client (WAN) on Windows 2000
>I've got a problem with an Apache 1.3.33 installation on
>windows 2000 related to throughput, I can't understand what is
>When I request a file from the local lan, the throughput is
>good and quite full, but when I fetch file from the internet (
>we have a 180 KB/s link ) using clients with latency in
>average around 100ms, the total througput seems capped and
>limited to 40 KB/s .
>If I use the same client and I fetch the same file using the
>FTP protocol, I get full bandwidth usage ( 160-170 KB/s ).
>If I fetch the same file from an instance of IIS installed on
>the same server and same tcp port, the throughput is full,
>like FTP ( 160-170 KB/s ).
>If I fetch the same file from an instance of Apache version 2
>installed on the same server and tcp port, the throughput
>seems again limited, but bigger than 1.3.33 ( 90 KB / s ).
>The file in question is 10 MB big.
>So according to this tests, to me it is not an ethernet
>interface problem, nor a wrong configured tcp ip settings, nor
>an in-path router/firewall that do bandwidth limiting.
>The only conclusion that I can make is that it seems that
>Apache sets or force the trasmit tcp window (not honoring
>client declared receive window, or host setting ) in some
>limiting way so that on high latency clients the problem shows
>up ( but not on local lan ethernet where latency is very low ).
>It is a known problem / how can I avoid the problem?
>Thanks you much all for your time
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