Re: process creation time increases linearly with shmem

[Ray Fucillo]

Nick Piggin wrote:
> fork() can be changed so as not to set up page tables for
> MAP_SHARED mappings. I think that has other tradeoffs like
> initially causing several unavoidable faults reading
> libraries and program text.
>
> What kind of application are you using?

The application is a database system called Caché.  We allocate a large 
shared memory segment for database cache, which in a large production 
environment may realistically be 1+GB on 32-bit platforms and much 
larger on 64-bit.  At these sizes fork() is taking hundreds of 
miliseconds, which can become a noticeable bottleneck for us.  This 
performance characteristic seems to be unique to Linux vs other Unix 
implementations.

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