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From Stanislav Rost <prgrs...@cs.bu.edu>
Subject Re: Behavior Under Linux, Benchmarking Curves and Cry for Help
Date Thu, 22 Mar 2001 19:41:35 GMT
Blue and many others,

Thanks for the response.  You are right, I need to provide a few more
details.

The files are 10 MBs each, the Apache version is 1.2.12 (should I
upgrade?  were there scalability enhancements since then?), the Linux
kernel version is 2.2.19pre16 (unfortunately, I cannot go above 2.2.x for
the purposes of this test).

The following limits were increased in the Linux kernel:  NR_TASKS (max
processes) to 4000, FD_SETSIZE (max open files) to 4096, various TCP
parameters in /proc/sys/net/ipv4, etc.  Am I forgetting something?  Is
there a good online guide to tweaking your Linux to handle higher loads
that I am perhaps not aware of?

Actually, the problem that I am having is not so much with Apache waiting.
It's with the resets.

Another thing that I was not aware of is the need to bump up MAX_PROCESSES
in http_main.c manually.  I always sort of assumed changing
process-related parameters in the httpd.conf would do the trick.  So I
will try increasing that now...  Are there any other limits
defined in the source-code that may need to be increased?

Thank you very much.

Stan Rost

On Thu, 22 Mar 2001, Blue Lang wrote:

> On Wed, 21 Mar 2001, Stanislav Rost wrote:
> 
> > A little about the setup:  two P2-400's stressing another P2-400 with
> > >400-500 concurrent ongoing downloads of large files at any given
> > instant of time (so high concurrency levels are implicit).  Apache is
> > directed to create at least that many threads on startup.
> 
> how large are the files? what version of apache are you using? why are you
> using http to transfer large files? it's stinky at it.
> 
> if it's a 1MB file, you're out of bandwidth in .002 seconds (on a 100Mb
> link) and apache will queue up the rest of your downloads and wait, wait,
> wait.
> 
> > My other question is for anyone who has ever successfully benchmarked
> > Apache under Linux and produced nice-looking graphs:  what system and
> > web server parameters did you tweak to obtain high-stress results?
> > What was your setup?
> 
> i've been able to maintain load avgs of around 230 on a late 2.3 kernel on
> a celeron 433, pushing about 1300 reqs/second over a 100Mb switch. i was
> using ab and a smallish (~3k) index.html. the only things i did were turn
> off logging and set max clients to 255. i was experimenting with serving
> files from RAM disks and loopback mounted file systems at the time, it was
> nothing scientific.
> 
> anyways, that's 1,000,000 small requests every 10 minutes or so.  this was
> probably with apache 1.3.12 or so.
> 
> on a really nice switch with a dual proc sun Netra, i was able to get
> really close to 11MB/sec from an apache install tuned pretty much the same
> way with very, very low load on the web server.
> 
> -- 
>    Blue Lang                                    http://www.gator.net/~blue
>    2315 McMullan Circle, Raleigh, North Carolina, USA         919 835 1540
> 
> 


--------------------------------------------------
  Stanislav "Stan" Rost                         /
  A.K.A. The Progressor                        / 
                                              /
  http://cs-people.bu.edu/prgrssor           / 
--------------------------------------------' 





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