svn commit: r275121 - in head/sys: compat/linux compat/svr4 fs/procfs kern sys

[Chagin Dmitry]

On Wed, Nov 26, 2014 at 02:10:00PM +0000, Konstantin Belousov wrote:
> Author: kib
> Date: Wed Nov 26 14:10:00 2014
> New Revision: 275121
> URL: https://svnweb.freebsd.org/changeset/base/275121
> 
> Log:
>   The process spin lock currently has the following distinct uses:
>   
>   - Threads lifetime cycle, in particular, counting of the threads in
>     the process, and interlocking with process mutex and thread lock.
>     The main reason of this is that turnstile locks are after thread
>     locks, so you e.g. cannot unlock blockable mutex (think process
>     mutex) while owning thread lock.
>   
>   - Virtual and profiling itimers, since the timers activation is done
>     from the clock interrupt context.  Replace the p_slock by p_itimmtx
>     and PROC_ITIMLOCK().
>   
>   - Profiling code (profil(2)), for similar reason.  Replace the p_slock
>     by p_profmtx and PROC_PROFLOCK().
>   
>   - Resource usage accounting.  Need for the spinlock there is subtle,
>     my understanding is that spinlock blocks context switching for the
>     current thread, which prevents td_runtime and similar fields from
>     changing (updates are done at the mi_switch()).  Replace the p_slock
>     by p_statmtx and PROC_STATLOCK().
>   
>   The split is done mostly for code clarity, and should not affect
>   scalability.
>   
>   Tested by:	pho
>   Sponsored by:	The FreeBSD Foundation
>   MFC after:	1 week
hi, any chance to merge it?