Date: Sun, 16 Jan 2005 16:42:56 -0800 (PST) From: stheg olloydson <stheg_olloydson@yahoo.com> To: freebsd-questions@freebsd.org Subject: Re: different behaviour between 4.x and 5.x (ping response/disk io) [was Re: ] Message-ID: <20050117004256.33118.qmail@web53901.mail.yahoo.com>
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(Sorry about the multiple posts. I somehow sent this without a subject line before.) it was said: >Now i am really puzzled because i cannot understand why 4.x behaves >relatively good compared to 5.x on this specific issue. Is there a >good explanation or does one have to investigate this further? Hello, First, I do not speak for anyone but myself. Therefore, any information this post contains is based solely on my understanding of that information and is only as accurate as that understanding is correct. To sum up your problem, you tested "FreeBSD 5.3, NetBSD 2.0, FreeBSD 4.11 and an elder version of the Knoppix (Linux 2.4) CD" and found that FreeBSD 4.11RC2 had the best ping responses from that group. What you want to know is why FBSD 5.3 doesn't respond as well as 4.11RC2. Is this correct? Assuming that it is, the answer is that 5.3 is the first stable release of the 5.x branch. One of the 5.x branch's main purposes is to make FBSD much more scalable in terms SMP support. Doing this requires removing the Giant lock. It had been hoped that the removal process would be finished in time for 5.3. Unfortunately, as often happens in a volunteer project delays occurred for various reasons, that was not the case. The incomplete removal meant that not all subsystems could be optimized properly. One of those subsystems is networking. This is not as bad as it sounds because while 5.3's network performance is not as good as 4.11RC2, it is no worse that of NBSD 2.0 or any Linux distro. Also, the optimization has already begun on networking and 5.4 should be _at least_ as good as 4.x. Also, as you saw yourself, using an SMP kernel in FBSD 5.3 doesn't cause a performance hit in networking but it does in NBSD 2.0. So your choices seem to be use 4.11RC2 (full release due shortly) to get the best network response, 5.3 to get as good performance as NBSD 2.0 but with SMP, or use NBSD 2.0 to get as good perfomance as 5.3 but without SMP. Of course, you can wait until NBSD (your prefered OS) performs as well as FBSD, but that may be a loooonng time.:) HTH, stheg P.S. (to the list in general) Why do all of the questions about FBSD performance, especially 4.x vs 5.x, come from people posting from Windows boxes? Theories? __________________________________ Do you Yahoo!? Yahoo! Mail - now with 250MB free storage. Learn more. http://info.mail.yahoo.com/mail_250
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