%
%
%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
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