Date: Thu, 3 Aug 1995 22:12:58 -0700 (PDT) From: John Dyson <dyson> To: jiho@sierra.net Cc: davidg@Root.COM, freebsd-questions@freefall.cdrom.com Subject: Re: 2.0.5 Eager to go into swap Message-ID: <199508040512.WAA19121@freefall.cdrom.com> In-Reply-To: <199508040309.AA11016@diamond.sierra.net> from "Jim Howard" at Aug 3, 95 07:12:39 pm
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These issues regarding swapping are interesting, but I have some anecdotal evidence regarding the quality of hardware making a big difference in system perf. As you all know, I am a member of the FreeBSD core team and have alot at stake regarding my professional reputation. I work at a very big communications company and we had the need to put together a large (FreeBSD) Unix box and alot of small ones too. The small ones need to run X and Netscape in 8MB!!! To put it mildly, my coworkers were not impressed with the system performance (nor was I.) Well, I did a bit of analysis and found that the Connor 204 IDE drive was a bit slow :-). I installed a Quantum Fireball(?) drive and the system is now very snappy. :-). Problem solved... Note that we also upgraded the processor from a 486/33 to a DX4/100, and noticed only a minor difference in performance. I suspect that part of the reason for the varied performance reports has partially to do with disk performance among other things. Paging performance depends very highly on your disk performance and there is almost no way around that simple fact!!! I will also re-iterate something that I sent to someone in private email -- IF YOU ARE ALMOST RUNNING OUT OF SWAP SPACE, YOUR PERFORMANCE WILL SUFFER SIGNIFICANTLY!!! This has to do with the X server taking up all of the anonymous backing store and paging will then occur almost exclusively against vnode backed objects. This will kill performance because there are probably other swap-backed pages that could be paged out, but can't be -- thereby clogging up memory... John dyson@root.com
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