Re: FW: Filesystem gets a huge performance boost

[Rik van Riel]

On Tue, 17 Apr 2001, Matt Dillon wrote:

> :You need to settle dude, pre-emption isn't a goal, it's mearly a 
> :_possible_ side effect.
> :
> :We're not aiming for pre-emption, we're aiming for more concurrancy.
> 
>     A goal of having more concurrency is laudable, but I think you are 
>     ignoring the costs of doing task switches verses the likely spin time
>     for a mutex.  The whole point of using fine-grained Mutexes is to not
>     have significant performance-effecting collisions in the first place,
>     so why bother to try to task switch if you wind up spining in one? 

Exactly.

It makes absolutely no sense to optimise mutexes for the case
of having contention.  If you have contention, you need to fix
the contention, not introduce all kinds of singing-dancing cool
things you can do when contention happens.

Rik
--
Virtual memory is like a game you can't win;
However, without VM there's truly nothing to lose...

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