RE: [squid-users] squid 3.2.0.5 smp scaling issues

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> Date: Sun, 12 Jun 2011 19:54:10 +1200
> From: squid3_at_treenet.co.nz
> To: squid-users_at_squid-cache.org
> Subject: Re: [squid-users] squid 3.2.0.5 smp scaling issues
>
> On 12/06/11 18:46, Jenny Lee wrote:
> >
> > On Sat, Jun 11, 2011 at 9:40 PM, Jenny Lee wrote:
> >
> > I like to know how you are able to do>13000 requests/sec.
> > tcp_fin_timeout is 60 seconds default on all *NIXes and available ephemeral port range is 64K.
> > I can't do more than 1K requests/sec even with tcp_tw_reuse/tcp_tw_recycle with ab. I get commBind errors due to connections in TIME_WAIT.
> > Any tuning options suggested for RHEL6 x64?
> > Jenny
> >
> > I would have a concern using both those at the same time. reuse and recycle. Reuse a socket, but recycle it, I've seen issues when testing my own linux distro's with both of these settings. Right or wrong that was my experience.
> > fin_timeout, if you have a good connection, there should be no reason that a system takes 60 seconds to send out a fin. Cut that in half, if not by 2/3's
> > And what is your limitation at 1K requests/sec, load (if so look at I/O) Network saturation? Maybe I missed an earlier thread and I too would tilt my head at 13K requests sec!
> > Tory
> > ---
> >
> >
> > As I mentioned, my limitation is the ephemeral ports tied up with TIME_WAIT. TIME_WAIT issue is a known factor when you are doing testing.
> >
> > When you are tuning, you apply options one at a time. tw_reuse/tc_recycle were not used togeter and I had 10 sec fin_timeout which made no difference.
> >
> > Jenny
> >
> >
> > nb: i still dont know how to do indenting/quoting with this hotmail... after 10 years.
> >
>
> Couple of thing to note.
> Firstly that this was an ab (apache bench) reported figure. It
> calculates the software limitation based on speed of transactions done.
> Not necessarily accounting for things like TIME_WAIT. Particularly if it
> was extrapolated from say, 50K requests, which would not hit that OS limit.
 
Ab accounts for 200-OK responses and TIME_WAITS cause squid to issue 500. Of course if you send in 50K it would not be subject to this but I usually send couple 10+ million to simulate load at least for a while.

 
> He also mentioned using a "local IP address". If that was on the lo
> interface. It would not be subject to things like TIME_WAIT or RTT lag.
 
When I was running my benches on loopback, I had tons of TIME_WAITS for 127.0.0.1 and squid would bail out with: "commBind: Cannot bind socket..."
 
Of course, I might be doing things wrong.
 
I am interested in what to optimize on RHEL6 OS level to achieve higher requests per second.
 
Jenny
 
 
 
 
 
 
 
 
 
 
                                                
Received on Sun Jun 12 2011 - 08:30:34 MDT