From: Len Brown <lenb@kernel.org>
To: Ingo Molnar <mingo@elte.hu>
Cc: Ben Greear <greearb@candelatech.com>,
Thomas Gleixner <tglx@linutronix.de>,
linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: PATCH: Allow over-ride of smp_found_cfg with kernel cmd-line option.
Date: Fri, 06 Feb 2009 22:00:54 -0500 (EST) [thread overview]
Message-ID: <alpine.LFD.2.00.0902062157490.26256@localhost.localdomain> (raw)
In-Reply-To: <20090206193121.GA32634@elte.hu>
> > Without this override, performance drops by around 15% on
> > network throughput tests on this system.
>
> The question is, _why_ does network performance drop?
>
> Do you have a before/after pair of /proc/interrupts output
> perhaps? Does the layout of IRQs change?
>
> The system is not SMP - so only something about UP-IOAPIC can
> be helpful to performance here - or some unknown effect.
I presume it is IOAPIC (good) vs PIC (bad), for the
patch that provoked this regression was one that caused
the MPS table to be disabled. (the problem with that patch
was that it was effective not just in ACPI mode, but in acpi=off mode)
The other un-answered question is why the system under test
has ACPI disabled in the BIOS when it did not ship that
way from the manufacturer.
cheers,
-Len
Intel Open Source Technology Center
prev parent reply other threads:[~2009-02-07 3:01 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-02-05 19:46 Ben Greear
2009-02-05 19:52 ` Randy Dunlap
2009-02-05 19:58 ` Ingo Molnar
2009-02-05 20:45 ` Ben Greear
2009-02-06 19:21 ` PATCH: (v2) " Ben Greear
2009-02-06 19:30 ` Randy Dunlap
2009-02-06 19:34 ` Yinghai Lu
2009-02-06 20:27 ` PATCH: (v3) " Ben Greear
2009-02-07 2:57 ` Len Brown
2009-02-06 19:31 ` PATCH: " Ingo Molnar
2009-02-07 3:00 ` Len Brown [this message]
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