Message-Id: <200503311953.j2VJrog22170@unix-os.sc.intel.com>
From: "Chen, Kenneth W" <kenneth.w.chen@intel.com>
To: "'Ingo Molnar'" <mingo@elte.hu>
Cc: "'Nick Piggin'" <nickpiggin@yahoo.com.au>,
       "Linus Torvalds" <torvalds@osdl.org>, "'Andrew Morton'" <akpm@osdl.org>,
       <linux-kernel@vger.kernel.org>
Subject: RE: Industry db benchmark result on recent 2.6 kernels
Date: Thu, 31 Mar 2005 11:53:50 -0800
Thread-Index: AcU1/Bu0D5SGrTCsSzGaoo/aEx5CZAALgmuw
In-Reply-To: <20050331141441.GA2384@elte.hu>
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 1219
Lines: 22

Ingo Molnar wrote on Thursday, March 31, 2005 6:15 AM
> is there any idle time on the system, in steady state (it's a sign of
> under-balancing)? Idle balancing (and wakeup balancing) is one of the
> things that got tuned back and forth alot. Also, do you know what the
> total number of context-switches is during the full test on each kernel?
> Too many context-switches can be an indicator of over-balancing. Another
> sign of migration gone bad can be relative increase of userspace time
> vs. system time. (due to cache trashing, on DB workloads, where most of
> the cache contents are userspace's.)

No, there are no idle time on the system. If system become I/O bound, we
would do everything we can to remove that bottleneck, i.e., throw a couple
hundred GB of memory to the system, or add a couple hundred disk drives,
etc.  Believe it or not, we are currently CPU bound and that's the reason
why I care about every single cpu cycle being spend in the kernel code.


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