[Xitami] Memory allocation

[Russel Olinger]

Good info, thanks.

For more specifics:
Server: HP DL380 G2, Dual Processor, 6Gb RAM, 6 146Gb RAID-5 drives, SCSI 
1Gb controller
OS: Windows 2003 Enterprise Server (32Bit) with /pae boot.ini option 
(extended memory from 4Gb to 6Gb)
Applications: DNS, Mail, MySql, Web

MySql maxes at 3.5Gb (what I have read).  I have set mysql max_connections 
at 1000 (for now) and optimized the cache(s) at 250Mb.  MySql is configured 
for MYISAM dbs.  Xitami > Perl > MySql will be the most intensive 
applications.  I ultimately will be moving Web/Perl, DNS, and Mail off of 
the above server as I expand.  However, until I expand, the 
Xitami/Perl/Mysql trio is my biggest concern when it comes to optimization.

Perl only gets executed as a result of cgi-bin files in Xitami.  And I 
believe I have tweaked MySql as best as I can get it (for now) so my biggest 
concern was configuring Xitami/Windows so that Xitami and OS wouldn't be a 
bottle neck.  I know soooo many people have said on many many occassions not 
to use Xitami for production.  But for the many years I have run I have 
NEVER had a problem with it and its been very trustworthy, fast and 
reliable.  I suspect though that my latest website is going to test all 
previous limits but I still want to give Xitami the chance it deserves as my 
production webserver.

Is it best to let Windows determine its own virtual memory or should I just 
set it 10Gb?  And I wish there was a way to completely dedicate, within 
Windows, physical ram to specific apps.

Thanks
-R

----- Original Message ----- 
From: "Paul Reid" <preid at rci.rutgers.edu>
To: "Xitami Users General Discussion" <xitami at lists.xitami.org>
Sent: Friday, October 12, 2007 3:25 PM
Subject: Re: [Xitami] Memory allocation


> >  is there anyway to provde the application more memory so that if it
> needs it, it is available.
>
> It's not Mac OS/6. Any 32-bit Win-app can request 2GB at any time. The
> whole point of virtual memory is that the app does not know if the 2GB
> is DRAM or hard drive or small angels with clay tablets.
>
> I've run Xitami and CGI in 8MB (obviously not Win2003). If a runaway
> script asks for 6MB, so the total system demand is 12MB in 8MB RAM, the
> request is satisfied though the system gets slow. The fix is to be sure
> you always have that 5MB (or whatever) to spare.
>
> Use Task Manager. "PF Usage" should flutter far below the Physical
> Memory number. Launching a CGI interpreter will spike it; VB6 runtime
> loads over 1MB of junk into RAM, but gives it back when it exits.
>
> My Xitami on Win2003 box is idling at 173MB total. Xitami is 5th on the
> process list with about 5MB used. Launching a small Perl script barely
> registers.
>
> Task Manager also shows CPU Usage. When code is not waiting on disk or
> I/O, this always spikes to 100%, but if it spikes and falls in a blink
> then you are not really limited by CPU.
>
> >  with 6Gb of memory
>
> I think Xitami has more than enough memory. Also VB, Perl, PHP.
>
> > The biggest slow down of the server is watching cgi-bin scripts kick 
> > off.
>
> What interpreter, and how heavy are the scripts? Even back in 133MHz
> 128MB RAM days, we could get away with quite sloppy code. One of my
> scripts opens and reads several text files, twice, because it was less
> programmer work than doing it once and the result was plenty fast.
> Another one must skim every file in a folder to get type and summary
> info, and it runs in a blink. If you are opening gigabyte databases, you
> probably don't want the script doing that, you want a persistent
> database server application which is already primed when the CGI asks
> for data.
>
> Apache has a way to keep PHP running all the time so you don't suffer a
> PHP interpreter load on every hit. But that only helps if you have a LOT
> of hits on scripts so easy that interpreter load-time exceeds script
> runtime.
>
> Interpreted scripts can sometimes be compiled, and run somewhat faster,
> if they are not disk-bound.
>
> In short: you need to know what's really taking time, and what resource
> it is bound in. And with 6GB, it seems unlikely that RAM-cram or memory
> allocation is the problem.
>
> -- 
> Paul Reid
> System Administrator
> Music Department
> Mason Gross School of the Arts
>
>
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