From: Dipankar Sarma <dipankar@in.ibm.com>
To: Ingo Molnar <mingo@elte.hu>
Cc: george anzinger <george@mvista.com>,
Linus Torvalds <torvalds@transmeta.com>,
linux-kernel@vger.kernel.org,
William Lee Irwin III <wli@holomorphy.com>,
Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>,
"David S. Miller" <davem@redhat.com>
Subject: Re: [patch] smptimers, old BH removal, tq-cleanup, 2.5.39
Date: Tue, 1 Oct 2002 11:03:05 +0530 [thread overview]
Message-ID: <20021001110305.B693@in.ibm.com> (raw)
In-Reply-To: <Pine.LNX.4.44.0210010542240.2564-100000@localhost.localdomain>; from mingo@elte.hu on Tue, Oct 01, 2002 at 05:51:45AM +0200
On Tue, Oct 01, 2002 at 05:51:45AM +0200, Ingo Molnar wrote:
> the smp_processor_id()/(HZ*num_cpus) 'interleaving' of every APIC clock
> was an SMP scalability issue, and it was done as part of the smptimers
> patch. It just got into the kernel much earlier.
>
> but these days, with the removal of BHs, it might be less of a factor,
> mainly because timers have no global synchronization anymore, so we can
> again try to not interleave the APIC clocks. Only testing will tell,
> because there might be some interaction between timer-generated code
> still.
Yes, with earlier versions of smptimers where global_bh_lock was
still being acquired to serialize with BHs, local timer clocks needed
to be spaced over a HZ to reduce contention. Archs that didn't space
the clocks perfromed poorly with smptimers as Anton found out with
ppc64 and had to change.
>
> Dipankar, wli, would it be possible to try the attached simple patch with
> some of the more complex networking loads? The patch gets rid of the APIC
> timer interleaving.
I will give it a spin.
Thanks
--
Dipankar Sarma <dipankar@in.ibm.com> http://lse.sourceforge.net
Linux Technology Center, IBM Software Lab, Bangalore, India.
next prev parent reply other threads:[~2002-10-01 5:22 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-09-29 17:52 [patch] smptimers, old BH removal, tq-cleanup, 2.5.39 Ingo Molnar
2002-09-29 18:38 ` Jeff Garzik
2002-09-29 18:50 ` Jeff Garzik
2002-09-29 19:27 ` Ingo Molnar
2002-09-29 19:48 ` Jeff Garzik
2002-09-29 18:54 ` Dave Jones
2002-09-29 19:15 ` Dipankar Sarma
2002-09-30 0:20 ` David S. Miller
2002-09-30 4:33 ` Dipankar Sarma
2002-09-30 4:28 ` David S. Miller
2002-09-30 4:38 ` Arnaldo Carvalho de Melo
2002-09-30 12:55 ` Alan Cox
2002-09-30 14:50 ` Arnaldo Carvalho de Melo
2002-09-29 19:16 ` Ingo Molnar
2002-09-30 0:39 ` David S. Miller
2002-09-30 6:06 ` Ingo Molnar
2002-09-30 21:45 ` george anzinger
2002-10-01 3:51 ` Ingo Molnar
2002-10-01 4:18 ` David S. Miller
2002-10-01 5:24 ` Ingo Molnar
2002-10-01 8:00 ` george anzinger
2002-10-01 5:33 ` Dipankar Sarma [this message]
2002-10-03 7:10 ` Dipankar Sarma
2002-09-30 23:37 ` Christoph Hellwig
2002-09-30 16:38 ` Ingo Molnar
2002-09-30 23:45 ` Christoph Hellwig
2002-09-30 17:12 ` Ingo Molnar
2002-10-01 0:43 ` Christoph Hellwig
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