Date: Tue, 25 May 1999 19:46:16 -0700 From: David Greenman <dg@root.com> To: Greg Lehey <grog@lemis.com> Cc: John Reynolds~ <jreynold@sedona.ch.intel.com>, freebsd-questions@FreeBSD.ORG Subject: Re: How 'tweaked' is ftp.cdrom.com ? Message-ID: <199905260246.TAA00797@implode.root.com> In-Reply-To: Your message of "Wed, 26 May 1999 12:01:43 %2B0930." <19990526120143.D667@freebie.lemis.com>
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>On Monday, 24 May 1999 at 15:30:28 -0700, John Reynolds~ wrote: >> >> Hey there, don't know if this is appropriate for -questions or -chat, but it >> *is* a question, so here goes: >> >> On slashdot.org today there was a posting about Wcarchive hitting 1.39Tb of >> info in 24 hours. Yeah! :) In the comments section there were all sorts of >> pseudo-FUD going around about how Linux could probably handle the same load >> and blah blah blah. >> >> My question is--how "tweaked" is the kernel that is running ftp.cdrom.com? I >> believe I've seen some postings in -current from David Greenman about >> maxusers and other kernel parameters and he mentioned some settings that were >> used on wcarchive. Well, how "tweaked" is that kernel vs. a "stock" 4.0-current >> or 3.2-RELEASE kernel? Is it a matter of knowing what parameters to tweak in >> the config file or are there lots of actual code changes? Somebody mentioned >> on slashdot that that machine is actually "using" all 4Gb of RAM. Are special >> boot blocks needed for this? > >Hmm. I had expected David to answer this one by now. AFAIK David has >some special kernel code in there which doesn't work in the general >case, but which improves performance in this specific application. On >the other hand, he's continually feeding back improvements into the >stock kernel. For example, until about 6 months ago the kernel had an >address space of 256 MB (address range 0xf0000000 to 0xffffffff). >This proved to be too little for very large memory systems, and it was >recently changed to 1 GB (address range 0xc0000000 to 0xffffffff). On >the current implementation, the rest is available for user programs, >but in practice we haven't seen any processes which required 3 GB of >address space. Most System V implementations give user and kernel >spaces 2 GB each. I guess I've been prodded enough. Wcarchive is running almost stock 3.2-stable. The only significant change to the source code is a further increase of the kernel virtual memory to 2GB (I increased the KVM to 1GB for the 3.2 release, but that's not quite enough for wcarchive). In the past, I've have brought in select performance improvements from -current development. FreeBSD 3.2 has most of the major performance improvements that -current has, however, so we're running escentially stock code now. This doesn't mean that I'm running "GENERIC", however. The kernel config file has been specially tuned as well as a variety of sysctl variables and a few other things. This tuning is what makes wcarchive special and is something that I do for my clients as needed for their specific application. -DG David Greenman Co-founder/Principal Architect, The FreeBSD Project - http://www.freebsd.org Creator of high-performance Internet servers - http://www.terasolutions.com To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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