Kernel preemption, yes or no? (was: Filesystem gets a huge performance boost)

[Greg Lehey]

On Tuesday, 17 April 2001 at  1:19:57 -0700, Alfred Perlstein wrote:
> * Matt Dillon <[EMAIL PROTECTED]> [010415 23:16] wrote:
>>
>>                               For example, all this work on a preemptive
>>     kernel is just insane.  Our entire kernel is built on the concept of
>>     not being preemptable except by interrupts.  We virtually guarentee
>>     years of instability and bugs leaking out of the woodwork by trying to
>>     make it preemptable, and the performance gain we get for that pain
>>     is going to be zilch.  Nada.  Nothing.
>
> Pre-emption is mearly a side effect of a mutex'd kernel.
>
> The actual gains are in terms of parallel execution internally.
> Meaning if we happen to copyin() a 4 meg buffer we can allow more
> than one process to be completing some sort of work inside the
> kernel other than spinning on the giant lock.

*sigh* Couldn't you have changed the subject line when discussing
something of this importance?

Greg
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