Douglas Allan Tutty wrote:

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> On Wed, May 09, 2007 at 01:30:41AM -0400, Daniel Ouellet wrote:

>> No swapping is happening, even with 1000 httpd running.

>>

>> load averages: 123.63, 39.74, 63.3285                      01:26:47

>> 1064 processes:1063 idle, 1 on processor

>> CPU states:  0.8% user,  0.0% nice,  3.1% system,  0.8% interrupt, 95.4%

>> idle

>> Memory: Real: 648M/1293M act/tot  Free: 711M  Swap: 0K/4096M used/tot

>>

>

> How does this server do with 1000 non-httpd processes running?  Perhaps

> I need a newer Nemeth et al, but in my 3rd edition, pg 759 middle of the

> page says "Modern systems do not deal welll with load averages over

> about 6.0".

Be careful when reading these numbers here. Don't forget that I am doing

this in labs with abuse, etc. I am trying to push the server as much as

I can here. In production, I do see some server reaching 10, 18 and some

time I saw up to 25, but all these were in extreme cases, most of the

time, it's always below 10.
I can't answer this question with proper knowledge here as I don't

pretend to know that answer. May be someone else can speak knowingly

about it?
> Could your bottleneck be in context-switching between so many processes?

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> With so many, the memory cache will be faulting during the context

> switching and have to be retreived from main memory.  I don't think that

> such slow-downs appear in top, and I don't know about vmstat.  I don't

> know if there's a tool to measure this on i386.

Wasn't. However yes there is and I can see faulting. I check both the

vmstat and iostat to see what's up. Obviously the number are higher on

older hardware as it run out of horse power obviously. But the problem

was the be able to handle more then 300 parallel connections and why it

just 3x when only 2 more process were added. So, no, I don't think the

context-switching had anything to do with it here.
You will see when I post the changes I did and the test I did. Some are

surprising!
> I've never run httpd but it looks to me like a massivly parralized

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> problem where each connection is trivial to serve (hense low CPU usage,

> no disk-io waiting) but there are just so many of them.  

One multi core and multi processor hardware with proper memory, it

shouldn't be a problem I think, but will know soon!
> How does the server do with other connection services, e.g. pop or ftp?
I only run one application per servers, always did and most likely

always will. So, any mail server is a mail server, and a web server is

only a web server here anyway. Even DNS are only running DNS as well, etc.