Date: Sun, 9 Apr 2006 03:58:13 +0100 From: "Joao Barros" <joao.barros@gmail.com> To: "Kris Kennaway" <kris@obsecurity.org> Cc: Miguel <mmiranda@123.com.sv>, freebsd-questions@freebsd.org, usleepless@gmail.com Subject: Re: terrible performance in 6.1beta4 Message-ID: <70e8236f0604081958y4fb58189wfd08510c60ae5abe@mail.gmail.com> In-Reply-To: <20060330205858.GA21147@xor.obsecurity.org> References: <442B2FC6.9040001@123.com.sv> <20060330011834.GA84658@xor.obsecurity.org> <c39ec84c0603300047u5530fc1fjb1ba93fcafcd490d@mail.gmail.com> <442BF0BB.8010504@123.com.sv> <c39ec84c0603301141g42f0f367i1c7669c90e1115d7@mail.gmail.com> <20060330202145.GA17856@xor.obsecurity.org> <c39ec84c0603301249s68475c2erdb87c49eec157c0@mail.gmail.com> <20060330205858.GA21147@xor.obsecurity.org>
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On 3/30/06, Kris Kennaway <kris@obsecurity.org> wrote: > Actually I seem to recall that on Linux with default settings fsync() > lies and does not actually sync data before returning, so maybe it's > worth turning off on FreeBSD too if you're comfortable with the > implications of this. > A few months ago I installed a syslog server with syslog-ng inserting the events to postgresql. Since I had 5000+ events per second coming in postgresql was my bottleneck and I had to disable fsync (Even then it would get very slow sometimes). This was on a CentOS 4.2 running kernel 2.6.9-22.0.1.ELsmp This to say, I don't know for sure if Linux is lying or not on fsync, but even on Linux, turning fsync off makes a big difference. In my case if data was lost there was no damage hence my choice to keeping it off -- Joao Barros
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