Date: Thu, 19 Aug 2004 15:31:11 +0800 From: sam <sam.wun@tech-21.com.hk> To: Marc Fonvieille <blackend@freebsd.org> Cc: Mike Tancsa <mike@sentex.net> Subject: Re: Weird performances: -CURRENT vs 5.2.1 Message-ID: <4124573F.50403@tech-21.com.hk> In-Reply-To: <20040819072614.GA19508@abigail.blackend.org> References: <20040818200530.GA88370@abigail.blackend.org> <20040818205029.GA48028@xor.obsecurity.org> <6.1.2.0.0.20040818170232.05773880@64.7.153.2> <20040819072614.GA19508@abigail.blackend.org>
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Marc Fonvieille wrote: >On Wed, Aug 18, 2004 at 05:05:13PM -0400, Mike Tancsa wrote: > > >>Hi, >> As someone who is also going to start testing the waters with >>RELENG_5 on some non critical production servers (e.g. one of n spam and av >>scanning machines), I take it you mean, >> >> >>NOTE TO PEOPLE WHO THINK THAT FreeBSD 5.x IS SLOW: >> FreeBSD 5.x has many debugging features turned on, in >> both the kernel and userland. These features attempt to detect >> incorrect use of system primitives, and encourage loud failure >> through extra sanity checking and fail stop semantics. They >> also substantially impact system performance. If you want to >> do performance measurement, benchmarking, and optimization, >> you'll want to turn them off. This includes various WITNESS- >> related kernel options, INVARIANTS, malloc debugging flags >> in userland, and various verbose features in the kernel. Many >> developers choose to disable these features on build machines >> to maximize performance. >> >> >>Are there more details somewhere as to what exactly to turn off and tweak ? >> >> >> > >It's not really documented. To sum up, you have to remove these lines >from your kernel configuration file: > >makeoptions DEBUG=-g # Build kernel with gdb(1) debug symbols > ># Debugging for use in -current >options KDB # Enable kernel debugger support. >options DDB # Support DDB. >options GDB # Support remote GDB. >options INVARIANTS # Enable calls of extra sanity checking >options INVARIANT_SUPPORT # Extra sanity checks of internal struct >ures, required by INVARIANTS >options WITNESS # Enable checks to detect deadlocks and cycles >options WITNESS_SKIPSPIN # Don't run witness on spinlocks for spe >ed > >In fact INVARIANTS and WITNESS related lines are the more important to >maximize performance, the others lines do not really change things. >And then do a: > >ln -s aj /etc/malloc.conf > > This looks like a trick. "aj" is actually not existed in the system. You meant created a malloc.conf pointing to a non-exist aj for the improvment of the malloc operation? root@fbsd [3:31pm] [...i386/conf]# ls -l /etc/malloc.conf lrwxr-xr-x 1 root wheel 2 Aug 19 15:31 /etc/malloc.conf@ -> aj root@fbsd [3:34pm] [...i386/conf]# root@fbsd [3:34pm] [...i386/conf]# ls -l /etc/aj ls: /etc/aj: No such file or directory root@fbsd [3:34pm] [...i386/conf]# Sam >This one is important too, by default malloc routines uses AJ flags (be >careful with the case) under -CURRENT, even if you don't have any >malloc.conf file, look at malloc(3) manual page for more details. > >Marc > >
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