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Date: Fri, 5 May 2017 13:56:09 +0100
From: Stefan Hajnoczi <stefanha@gmail.com>
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Subject: Re: [Qemu-devel] [Qemu-block] [PATCH 17/17] block: make accounting
 thread-safe
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To: Paolo Bonzini <pbonzini@redhat.com>
Cc: qemu-devel@nongnu.org, qemu-block@nongnu.org


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On Thu, Apr 20, 2017 at 02:00:58PM +0200, Paolo Bonzini wrote:
> I'm not trying too hard yet.  Later, with multiqueue support,
> this may cause cacheline bouncing.

This patch calls qemu_clock_get_ns() within a spinlock region.  It's
probably just a memory load, rdtsc, and some math but more heavy-weight
code paths are possible too.

Taking the clock reading outside the lock region should be fine and
reduces the chance of contention.

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