|
| From: | Sathya Thammanur |
| Subject: | Re: [lwip-users] Slow response times in Microblaze Webserver example |
| Date: | Mon, 25 Sep 2006 10:22:28 -0700 |
Hi Ed,
Thanks again. I guess I will have to bite the bullet and start an
implementation of the RAW_API. I really did not think that my really quite
modest requirements would not be met by the sockets version.
John Robbins
Quoting "Pisano, Edward A" < address@hidden>:
> Hi John,
> In experimenting with lwIP on MicroBlaze, I saw some significant
> performance improvements when I setup and enabled the data cache and
> instruction cache. Also, there are some other architectural things that
> can be done such as using the multi-channel memory (mch_opb_ddr) and
> placing certain structures that are accessed frequently, but run a small
> risk of be flushed from cache occasionally, into the dlmb section. I've
> been told the LMB is almost as fast as cache.
>
> In this environment with SOCKETS_API, I was to delay 10ms between 1400
> byte UDP datagrams transmitted from my laptop and echo'd back by the
> Spartan 3E before seeing any packet loss.
>
> Of late, I've extended the experiments to using the lwIP RAW_API. It is
> much, much faster. I've reduced the delay between UDP datagrams as low
> as 2ms for small file (50KB) echo back. In RAW_API, there's no
> xilkernel and you must take care of lwIP memory management yourself.
>
> Regards,
> Ed
> -----Original Message-----
> From: lwip-users-bounces+edward.pisano= address@hidden
> [mailto:address@hidden ] On Behalf Of
> address@hidden
> Sent: Sunday, September 24, 2006 6:40 PM
> To: Mailing list for lwIP users
> Subject: RE: [lwip-users] Slow response times in Microblaze Webserver
> example
>
> I compared timing for the same data transfer using a Netburner SB72 card
>
> (Coldfire MCF5272 @ 66MHz) with the Microblaze (Spartan3e starter kit @
> 50MHz)
> as the server. The client at the end of a short crossover cable was a
> newish
> IBM laptop running XP and reporting a 100bpsconnection, the code being
> written
> in C++ for .Net. In response to a GET request the server sent 1260 bytes
>
> (actually 315 integers). To see the output change in the client but
> without
> distorting the lwIP timing, the server program changed only the first
> and last
> integer values.
>
> The following lines show one transfer for each system. The request
> period was
> 500 millisecond. The first delta time therefore is the difference
> between this
> period and the time required for the previous transfer.
>
> Netburner
>
>
> 460385 IP IBM-F3860BD49B6.1081 > 192.168.0.200.80:
> S
> 1367389610:1367389610(0) win 65535 <mss
> "1460,nop,nop,sackOK>"
> 657 IP 192.168.0.200.80 > IBM-F3860BD49B6.1081:
> S
> 19071019:19071019(0) ack 1367389611 win 0
> <mss
> "1460,nop,nop,nop,eol>"
> 40 IP IBM-F3860BD49B6.1081 > 192.168.0.200.80:
> .
> ack 1 win 65535
> 926 IP 192.168.0.200.80 > IBM-F3860BD49B6.1081:
> .
> ack 1 win 4644
> 35211 IP IBM-F3860BD49B6.1081 > 192.168.0.200.80:
> P
> 1:31(30) ack 1 win 65535
> 2252 IP 192.168.0.200.80 > IBM-F3860BD49B6.1081:
> P
> 1:1261(1260) ack 31 win 4614
> 31 IP 192.168.0.200.80 > IBM-F3860BD49B6.1081:
> F
> 1261:1261(0) ack 31 win 0
> 31 IP IBM-F3860BD49B6.1081 > 192.168.0.200.80:
> .
> ack 1262 win 64275
> 39148
>
>
> Microblaze
>
>
> 349914 IP IBM-F3860BD49B6.1147 > 192.168.0.200.80:
> S
> 3416876235:3416876235(0) win 65535 <mss
> "1460,nop,nop,sackOK>"
> 21994 IP 192.168.0.200.80 > IBM-F3860BD49B6.1147:
> S
> 32027:32027(0) ack 3416876236 win 16384 <mss
> 1460>
> 50 IP IBM-F3860BD49B6.1147 > 192.168.0.200.80:
> .
> ack 1 win 65535
> 35108 IP IBM-F3860BD49B6.1147 > 192.168.0.200.80:
> P
> 1:31(30) ack 1 win 65535
> 20632 IP 192.168.0.200.80 > IBM-F3860BD49B6.1147:
> .
> ack 31 win 16354
> 25924 IP 192.168.0.200.80 > IBM-F3860BD49B6.1147:
> .
> ack 31 win 16384
> 32843 IP 192.168.0.200.80 > IBM-F3860BD49B6.1147:
> P
> 1:1261(1260) ack 31 win 16384
> 15552 IP 192.168.0.200.80 > IBM-F3860BD49B6.1147:
> F
> 1261:1261(0) ack 31 win 16384
> 52 IP IBM-F3860BD49B6.1147 > 192.168.0.200.80:
> .
> ack 1262 win 64275
> 152155
>
>
> The data transfer time for the Microblaze (33 msec) is more than ten
> times
> slower than the Netburner (2.2 msec). The overall time for the complete
> transaction for the Microblaze was 152 msec against the Netburner's 39
> msecs.
>
> I am sure I must be doing something wrong. These results are really most
>
> disappointing as I was hoping to replace the Netburner with a Microblaze
> based
> solution for our new DAQ system.
>
> I am using the same xilkernel and lwIP settings as in the Webserver
> example for
> the S3e board. Are there any different optimisations I should be using?
>
> Any help would be most appreciated.
>
> John Robbins.
>
>
> Quoting address@hidden:
>
> >
> > Hi Ed,
> >
> > Thanks for fast response.
> >
> > I removed the xil_printf messages and turned off LWIP_DEBUG. The Ping
> time
> > dropped from 215 to 16 millisecs.
> >
> > However when I run the GET request the time spent in the read function
> is
> > still
> > 2820 millisecs except for the very first time when both the client and
> server
> >
> > programs are loaded and run, then the time is 26 millisecs. Restarting
> either
> >
> > the client or server without restarting the other still results in the
> long
> > delay time. The other lwIP functions called by the Webserver code(eg
> accept,
> >
> > write) seem to be fast.
> >
> > Without the RS232 messages, the short response time when both server
> and
> > client
> > are restarted seems to be very consistent whereas before the short
> response
> > time was seen only under these conditions but then not always.
> >
> > Any more thoughts on resolving this problem would be most appreciated.
> >
> > John Robbins
> >
> > Quoting "Pisano, Edward A" <address@hidden>:
> >
> > > Hi John,
> > > I had seen similar slow response with the WebServer example. It
> turned
> > > out to be the debug output messages. The RS-232 output has a
> > > significant slowing effect on lwIP. In my case, ping replies were
> > > taking 1700ms to 3400ms on the Spartan 3E. I turned off LWIP_DEBUG
> and
> > > commented out my own xil_print() statements. Ping replies quickly
> > > dropped to 17ms-25ms.
> > >
> > > Regards,
> > > Ed
> > > -----Original Message-----
> > > From: lwip-users-bounces+edward.pisano=address@hidden
> > > [mailto: address@hidden ] On
> Behalf Of
> > > address@hidden
> > > Sent: Tuesday, September 19, 2006 5:47 AM
> > > To: address@hidden
> > > Subject: [lwip-users] Slow response times in Microblaze Webserver
> > > example
> > >
> > > Dear All,
> > >
> > > I have been testing a program modified from the Webserver example
> for
> > > the
> > > Xilinx Spartan3e Starter Kit. A client application on a PC connected
> to
> > > the
> > > board via a crossover cable issues a GET command, to which the
> server
> > > should
> > > respond with a short string, about 50 bytes.
> > >
> > > The problem that I am finding is that, although the response is
> > > occasionally
> > > very fast, 99% of the time the response may take several seconds.
> Since
> > > my
> > > eventual application is a fairly fast data acquisition requirement,
> this
> > > is a
> > > problem.
> > >
> > > To debug this, I first removed the mfs part of the Webserver
> example,
> > > then
> > > added GPIO calls to the LEDs before and after the read function in
> > > processConnection. Using an Ant8 logic analyser, I found that the
> time
> > > needed
> > > in this function was very occasionally 30 - 40 millisecs but almost
> > > always
> > > around 2900 millisecs.
> > >
> > > Using gdb, I traced the delay to the call in netconn_recv() to
> > > sys_mbox_fetch()
> > > which blocks for 3 seconds, then all the rest of code executes as
> > > expected. The
> > > fast response seems only to occur the first time both the client and
> > > server are
> > > run.
> > >
> > > In XPS I selected the debug output option, set the rs232 speed to
> 115kbs
> > > and
> > > directed the output to a file.
> > >
> > > During the block period the system appears to emit at least
> > > six "tcp_slowtmr:procssing active pcb messages" interspersed with
> some
> > > timeout
> > > messages.
> > >
> > > In case I was doing something wrong in the client code, I used the
> same
> > > program
> > > to talk to a Netburner card, issuing the same response to a GET
> request.
> > > The
> > > delays were of the order of a few millisecs.
> > >
> > > So I am sure I am doing something stupid in the server code and
> would
> > > really
> > > appreciate any help.
> > >
> > > JOhn Robbins.
> > >
> > >
> > >
> > >
> > >
> > >
> > > _______________________________________________
> > > lwip-users mailing list
> > > address@hidden
> > > http://lists.nongnu.org/mailman/listinfo/lwip-users
> > >
> > >
> > > _______________________________________________
> > > lwip-users mailing list
> > > address@hidden
> > > http://lists.nongnu.org/mailman/listinfo/lwip-users
> > >
> >
> >
> >
> >
> >
> > _______________________________________________
> > lwip-users mailing list
> > address@hidden
> > http://lists.nongnu.org/mailman/listinfo/lwip-users
> >
>
>
>
>
>
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