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From "Adam W. Dace" <colonelforbi...@gmail.com>
Subject Re: Can ATS keep more than 500mbit/s traffic for single instance?
Date Sat, 23 Nov 2013 04:47:13 GMT
Well, to be honest I haven't touched kernel.shmall lately.
However, I was for short while running PostgreSQL on my Mac(long story).

Right now it does differ from the Mac OS X default:

kern.sysv.shmall=32768

What I should do is backup the /etc/sysctl.conf file and revert everything
I'm not using to defaults.
I'll do that shortly, then try to change that setting again and see if it
still has the same effect.

Thanks for pointing this out.  I didn't realize I was impacting shared
memory.

Regards,



On Fri, Nov 22, 2013 at 10:02 PM, Leif Hedstrom <zwoop@apache.org> wrote:

>
> On Nov 21, 2013, at 9:11 PM, James Peach <jpeach@apache.org> wrote:
>
> >
> > On Nov 21, 2013, at 7:57 PM, Adam W. Dace <colonelforbin74@gmail.com>
> wrote:
> >
> >> Also, once you've gotten past your immediate problem and are looking to
> deploy my Wiki page may help:
> >>
> >> https://cwiki.apache.org/confluence/display/TS/WebProxyCacheTuning
> >>
> >> To call it "best practices" would be a bit much, but I spent quite a
> bit of time simply tuning ATS for my own uses.
> >> The page is finally stable(i.e. I'm done now) and I'm quite pleased.
>  I'm hoping once the next release is out the door
> >> I can start bugging the commiters to take a look and review it.
> >
> > Yes, that's a nice piece of work! The effect
> ofproxy.config.system.mmap_max is interesting; were you ble to test with
> tcmalloc?
>
> Yeah, I’m very curious and concerned about this at the same time. The
> background is that we used to do millions of mmap areas for the RAM cache.
> As far as I can tell, this is no longer true (but please correct me if I’m
> wrong). As such, we were even thinking of removing this configuration
> option entirely, see
>
>         https://issues.apache.org/jira/browse/TS-1822
>
>
> Curious, when you increased this, did you also increase the corresponding
> sysctl? That would be
>
>         kernel.shmall
>
>
> Meaning, unless you increased this setting above the default, increasing
> the ATS setting above that ought to have no impact. Also, on a box we run
> with 100GB of RAM cache, the total number of pages mmap’ed is only about
> 500, a far cry from where we’d need to increase
> proxy.config.system.mmap_max. The default for this setting is 2MB, but the
> system default is 64KB.
>
> Finally, why this setting would affect disk I/O is a conundrum. As far as
> I know, our main mmap usage is for the RAM cache.
>
> James, you got any brilliant thoughts / ideas on why this is ? We should
> perhaps test one of our prod boxes with mmap_max set to something much
> smaller (e.g. 64k).
>
> — Leif
>
>


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