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From: Linus Torvalds <torvalds@linux-foundation.org>
Date: Sat, 26 Mar 2011 12:30:36 -0700
Message-ID: <AANLkTin8jHz0a5oS4LWQCrYW2VDb9A0V2aL7O5dYaPBt@mail.gmail.com>
Subject: Re: [PATCH] slub: Disable the lockless allocator
To: Christoph Lameter <cl@linux.com>
Cc: Eric Dumazet <eric.dumazet@gmail.com>, Ingo Molnar <mingo@elte.hu>,
        Pekka Enberg <penberg@kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>, akpm@linux-foundation.org,
        tj@kernel.org, npiggin@kernel.dk, rientjes@google.com,
        linux-kernel@vger.kernel.org, linux-mm@kvack.org
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On Sat, Mar 26, 2011 at 12:18 PM, Christoph Lameter <cl@linux.com> wrote:
>
> Right. RSI should be in the range of the values you printed.
> However, the determination RSI is independent of the emulation of the
> instruction. If RSI is set wrong then we should see these failures on
> machines that do not do the instruction emulation. A kvm run with Ingo's
> config should show the same issues. Will do that now.

I bet it's timing-dependent and/or dependent on some code layout
issue. Why else would the totally pointless previous patch have made
any difference for Ingo (the "SLUB: Write to per cpu data when
allocating it" thing seems to be pure voodoo programming)?

That said, this early in the boot I don't think we should have any
parallelism going on, so I don't see what could make those kinds of
random effects.

                             Linus
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