% % %On Wed, 23 Jun 1999, Russell L. Carter wrote: % %> %> %Basically there are some applications and benchmarks for which FreeBSD %> %> uh, "benchmarks" only, until evidence is produced otherwise.
[...] %ok here are some of the problems.. % %Matt's changes allow dd to copy data at 2.5 times the rate it did before. %I consider dd to be an application. The problem is due to resource %handling in the kernel and results in large amounts of Idle CPU time. Ok, why doesn't this show up in any of the disk or network benchmarks? %Another primary problem with the FreeBSD kernel (being addressed by Kirk) %is that after writing a file, once the data has been queued for IO you %cannot read the data in that file (even though it is present) until the IO %is complete. With 64 tags, it is concievable that this could take a half %second on a modern disk. That's interesting. %These are problems shown up by the benchmarks but %which can be shown to affect ordinary operations. % %There are other problems related to SMP and the GKL.. %e.g.. two processes cannot access buffers at the same time, even though %they are both present , because only one of them is allowed in the kernel %at a time. Therefore One processor will spend a bunch of time at idle.. Yup. Thanks for filling us in! Russell To Unsubscribe: send mail to majord...@freebsd.org with "unsubscribe freebsd-hackers" in the body of the message
