On 15/09/2013 2:53 p. m., Davide Italiano wrote:
On Sun, Sep 15, 2013 at 9:27 PM, Pedro Giffuni <[email protected]> wrote:
Hi;
Just noticed this, in the old DtraceTODO wiki:
https://wiki.freebsd.org/DTraceTODO
There is mention of some use that Dtrace makes of Solaris's vmem
allocator, specifically vmem_create(), vmem_destroy(), vmem_alloc(), and
vmem_free(). These functions (not exact but similar ones) have
been brought to FreeBSD 10 (r252330).
According to opengrok we may just have to uncomment some Solaris
code in sys/cddl/contrib/opensolaris/uts/common/dtrace/dtrace.c
We need also to provide at least some sort of wrappers for e.g. flags
passed to vmem_alloc which takes VM_SLEEP in solaris while in FreeBSD
this is M_WAITOK etc...
This would reduce differences with the Solaris code but it has
to be examined carefully as I think John Birrell had already
solved the issue by providing the resource id's natively (kmem).
Just thought I would point it out ... It may be that it is not
worth spending too much time on it since the existing code should
just work.
vmem is designed to be a generic resource allocator. I still need to
analyze how Dtrace uses it but in general it provides better
scalability and less fragmentation wrt home-rolled allocators we have
in the kernel. FWIW, Illumos uses it for several things, e.g. pid/tid
allocation. It might worth a try.
FWIW, the next point in the old DTrace TODO list is that Solaris
has vmem_cache_*. Maybe providing a cache is something that may
be useful in FreeBSD too.
Regards,
Pedro.
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