Date: Fri, 7 Oct 2005 14:22:29 +0400 From: Gleb Smirnoff <glebius@FreeBSD.org> To: dima <_pppp@mail.ru> Cc: arch@FreeBSD.org Subject: Re: [REVIEW/TEST] polling(4) changes Message-ID: <20051007102229.GL14542@cell.sick.ru> In-Reply-To: <E1ENpJK-000Gys-00._pppp-mail-ru@f7.mail.ru> References: <20051007094712.GK14542@cell.sick.ru> <E1ENpJK-000Gys-00._pppp-mail-ru@f7.mail.ru>
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On Fri, Oct 07, 2005 at 02:18:42PM +0400, dima wrote:
d> The loop body should really look like
d> if( mtx_try_lock( &iface_lock[i] ) ) {
d> pr[i].handler( pr[i].ifp, POLL_ONLY, count );
d> mtx_unlock( &iface_lock[i] );
d> }
d> I skipped this first to make the idea clearer.
Yes, this approach should be better.
d> > Really we do not have several kernel threads in polling. netisr_poll() is always
d> > run by one thread - swi1:net. Well, we have also idle_poll thread, but it is
d> > very special case. Frankly speaking, it can't work without help from netisr_poll().
d> > The current polling is designed for a single threaded kernel, for RELENG_4. We
d> > can't achieve parallelization with strong redesign. The future plans are to create
d> > per-interface CPU bound threads. The plans can change. You are welcome to help.
d>
d> idle_poll can significantly increase network response time. I'd suggest per-CPU (not per-interface) threads. This would keep user_frac code much simpler.
No, please don't spawn more idle_poll threads! :)
As said, the idle_poll thread can't work on its own. idle_poll needs netisr_poll()
to push it sometimes out of the priority pit. It is described in first mail of
this thread.
d> Not sure about the coding help in the next weeks. My current project is on the pre-release stage and the kid is going to be born soon. I can join a bit later though.
There is no promises in the free project. Join when you can.
--
Totus tuus, Glebius.
GLEBIUS-RIPN GLEB-RIPE
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