Re: process creation time increases linearly with shmem

[Andi Kleen <ak@suse.de>]

Ray Fucillo <fucillo@intersystems.com> writes:
> 
> 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.

You could set up hugetlbfs and use large pages for the SHM (with SHM_HUGETLB);
then the overhead of walking the pages of it at fork would be much lower.

-Andi