From owner-freebsd-net@freebsd.org  Sun Apr 15 14:19:41 2018
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From: "Rodney W. Grimes" <freebsd-rwg@pdx.rh.CN85.dnsmgr.net>
Message-Id: <201804151419.w3FEJVi4046362@pdx.rh.CN85.dnsmgr.net>
Subject: Re: High rate of NFS cache misses after upgrading from 10.3-prerelease
 to 11.1-release
In-Reply-To: <5AD3554C.8030906@grosbein.net>
To: Eugene Grosbein <eugen@grosbein.net>
Date: Sun, 15 Apr 2018 07:19:31 -0700 (PDT)
CC: Rick Macklem <rmacklem@uoguelph.ca>,
 Niels Kobschaetzki <niels@kobschaetzki.net>,
 "freebsd-net@freebsd.org" <freebsd-net@freebsd.org>
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[ Charset windows-1252 unsupported, converting... ]
> 15.04.2018 19:58, Rick Macklem wrote:
> 
> > Niels Kobschaetzki wrote:
> > [stuff snipped]
> >> It is a website with quite some traffic handles by three webservers behind a pair >of loadbalancers.
> >> We see a loss of 20% in speed(TTFB reduced by 100ms; sounds not a lot but >Google et al doesn?t like it at all) after upgrading to 11.1 with a combined upgrade >to php7.1. On another server without NFS that upgrade improved performance >considerably (I was told ca 30% by the front end-dev)
> > One thing you could try is booting the 11.1 kernel on an 10.3 system. Newer
> > FreeBSD kernels should work with older userland.
> 
> Though one should remember that some important system utilities
> may and probably will not work with newer kernel, like /sbin/ipfw, route,
> ifconfig, netstat etc.

I thought that as long as the newer kernel has the right
COMPAT_FREEBSD10 compiled in that all this stuff should work.
Am I miss understanding this kernel option?

> 
> > This would tell you if it is kernel changes or userland changes that are causing
> > the higher miss rate.
> 

-- 
Rod Grimes                                                 rgrimes@freebsd.org