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From: Richard Cochran <richardcochran@gmail.com>
To: Hadar Hen-Zion <hadarh@dev.mellanox.co.il>
Cc: Shawn Bohrer <shawn.bohrer@gmail.com>,
	Tom Ketterhagen <tomk@rgmadvisors.com>,
	netdev <netdev@vger.kernel.org>, Amir Vadai <amirv@mellanox.com>,
	Or Gerlitz <ogerlitz@mellanox.com>,
	Hadar Hen Zion <hadarh@mellanox.com>,
	"David S. Miller" <davem@davemloft.net>
Subject: Re: [PATCH net-next 1/2] mlx4_en: Add PTP hardware clock
Date: Thu, 26 Dec 2013 15:49:08 +0100	[thread overview]
Message-ID: <20131226144908.GA4360@netboy> (raw)
In-Reply-To: <20131226144111.GB12695@mtl-eit-vdi-41.mtl.labs.mlnx>

On Thu, Dec 26, 2013 at 04:41:11PM +0200, Hadar Hen-Zion wrote:

> +u64 mlx4_en_timecounter_read(struct mlx4_en_dev *mdev)
> +{
> +	struct timecounter *new_tc, *old_tc;
> +	unsigned long flags;
> +	s64 now;
> +
> +	new_tc = kmalloc(sizeof(*new_tc), GFP_KERNEL);

So you want to call malloc/free on every clock read?
That is crazy.

> +	spin_lock_irqsave(&mdev->clock_lock, flags);
> +	old_tc = mdev->clock;
> +	*new_tc = *old_tc;
> +	now = timecounter_read(new_tc);
> +	rcu_assign_pointer(mdev->clock, new_tc);
> +	spin_unlock_irqrestore(&mdev->clock_lock, flags);
> +	synchronize_rcu();
> +	kfree(old_tc);
> +
> +	return now;
> +}

Thanks,
Richard

  reply	other threads:[~2013-12-26 14:49 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-12-17 20:32 [PATCH net-next 0/2] mlx4_en: Add PTP support Shawn Bohrer
2013-12-17 20:32 ` [PATCH net-next 1/2] mlx4_en: Add PTP hardware clock Shawn Bohrer
2013-12-17 21:04   ` Or Gerlitz
2013-12-17 21:46     ` Shawn Bohrer
2013-12-18  7:59       ` Or Gerlitz
2013-12-18 15:03         ` Shawn Bohrer
2013-12-22 13:13   ` Hadar Hen Zion
2013-12-23 16:29     ` Shawn Bohrer
2013-12-23 16:59       ` Shawn Bohrer
2013-12-24 15:38         ` Hadar Hen Zion
2013-12-25 11:49           ` Richard Cochran
2013-12-23 18:48     ` Richard Cochran
2013-12-24 13:58       ` Hadar Hen Zion
2013-12-25 11:53         ` Richard Cochran
     [not found]           ` <CAKBbMu33zXkG4+S1kP6zB+4iKMNNoy=XVBtoqZZEkqurRsgvQw@mail.gmail.com>
2013-12-25 17:02             ` Richard Cochran
2013-12-26  8:26           ` Hadar Hen Zion
2013-12-26  8:33             ` Hadar Hen Zion
2013-12-26  9:17               ` Richard Cochran
2013-12-26 14:41                 ` Hadar Hen-Zion
2013-12-26 14:49                   ` Richard Cochran [this message]
2013-12-17 20:32 ` [PATCH net-next 2/2] mlx4_en: Only cycle port if HW timestamp config changes Shawn Bohrer

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