From: Dipankar Sarma <dipankar@in.ibm.com>
To: "J.A. Magallon" <jamagallon@able.es>
Cc: Anton Blanchard <anton@samba.org>,
linux-kernel@vger.kernel.org, Ingo Molnar <mingo@elte.hu>,
Alan Cox <alan@lxorguk.ukuu.org.uk>,
Dave Miller <davem@redhat.com>
Subject: Re: [RFC][PATCH] TIMER_BH-less smptimers
Date: Tue, 21 May 2002 11:48:50 +0530 [thread overview]
Message-ID: <20020521114850.A18654@in.ibm.com> (raw)
In-Reply-To: <20020516185448.A8069@in.ibm.com> <20020520085500.GB14488@krispykreme> <20020520212109.GA5821@werewolf.able.es>
On Mon, May 20, 2002 at 11:21:09PM +0200, J.A. Magallon wrote:
>
> >> I have been experimenting with Ingo's smptimers and I ended up
> >> extending it a little bit. I would really appreciate comments
> >> on whether these things make sense or not.
> >
> >I tried it out and found that we were context switching like crazy.
> >It seems we were always running the timers out of a tasklet because
> >we never unlocked the net_bh_lock.
> >
>
> The patch for 2.4 in
>
> http://people.redhat.com/mingo/scalable-timers-patches/
>
> does not acquire net_bh_lock. Then I suppose it does not apply to that ?
No. Ingo's smptimers doesn't have this problem. However I am not
sure if this patch has timers completely serialized with respect
to old protocol code that ran from NET_BH earlier. See
deliver_to_old_ones() in net/core/dev.c. Unless I am missing something
big, disabling TIMER_BH there doesn't stop timers from firing
in run_local_timers().
> Can I try your patch for 2.5 on 2.4 or is there any infrastructure
> missing ?
Only 2.5ish thing I use is the per-cpu area APIs from Rusty for
the per-cpu tasklet in timer.c. You can replace it by
an array of NR_CPUS tasklets each cache line aligned.
Thanks
--
Dipankar Sarma <dipankar@in.ibm.com> http://lse.sourceforge.net
Linux Technology Center, IBM Software Lab, Bangalore, India.
prev parent reply other threads:[~2002-05-21 6:16 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-05-16 13:24 [RFC][PATCH] TIMER_BH-less smptimers Dipankar Sarma
2002-05-20 8:55 ` Anton Blanchard
2002-05-20 10:29 ` Dipankar Sarma
2002-05-20 13:31 ` Anton Blanchard
2002-05-21 6:26 ` Dipankar Sarma
2002-05-20 12:38 ` Dipankar Sarma
2002-05-20 21:21 ` J.A. Magallon
2002-05-21 6:18 ` Dipankar Sarma [this message]
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