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Date: Thu, 4 May 2017 15:36:15 +0800
From: Fam Zheng <famz@redhat.com>
Message-ID: <20170504073615.GF19184@lemon.lan>
References: <20170420120058.28404-1-pbonzini@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH 09/17] util: add stats64 module
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To: Paolo Bonzini <pbonzini@redhat.com>
Cc: qemu-devel@nongnu.org, qemu-block@nongnu.org

On Thu, 04/20 14:00, Paolo Bonzini wrote:
> +static inline void stat64_rdlock(Stat64 *s)
> +{
> +    /* Keep out incoming writers to avoid them starving us. */
> +    atomic_add(&s->lock, 2);
> +
> +    /* If there is a concurrent writer, wait for it.  */
> +    while (atomic_read(&s->lock) & 1) {
> +        g_usleep(5);

What's the difference of g_usleep() from cpu_relax() in
qemu_co_mutex_lock_unlock?

> +    }
> +}

Fam