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From: Eli Cohen <eli-LDSdmyG8hGV8YrgS2mwiifqBs+8SCbDb@public.gmane.org>
To: roland-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org,
	RDMA list <linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>
Subject: mlx4_wq_overflow question
Date: Thu, 9 Feb 2012 00:45:46 +0200	[thread overview]
Message-ID: <20120208224546.GA31369@mtldesk30> (raw)

Hi Roland,

referring to the function below, I can't find a strong reason to check
again after acquiring the cq spinlock. Any idea?

static int mlx4_wq_overflow(struct mlx4_ib_wq *wq, int nreq, struct
ib_cq *ib_cq)
{
        unsigned cur;
        struct mlx4_ib_cq *cq;

        cur = wq->head - wq->tail;
        if (likely(cur + nreq < wq->max_post))
                return 0;

        cq = to_mcq(ib_cq);
        spin_lock(&cq->lock);
        cur = wq->head - wq->tail;
        spin_unlock(&cq->lock);

        return cur + nreq >= wq->max_post;
}
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             reply	other threads:[~2012-02-08 22:45 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-02-08 22:45 Eli Cohen [this message]
2012-02-09 17:39 ` mlx4_wq_overflow question Roland Dreier

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