From: Amir Vadai <amirv@mellanox•com>
To: Eric Dumazet <eric.dumazet@gmail•com>
Cc: "David S. Miller" <davem@davemloft•net>, <netdev@vger•kernel.org>,
Richard Cochran <richardcochran@gmail•com>,
Or Gerlitz <ogerlitz@mellanox•com>,
Eugenia Emantayev <eugenia@mellanox•com>
Subject: Re: [PATCH net-next V2 5/5] net/mlx4_en: Add a service task
Date: Tue, 23 Apr 2013 16:56:43 +0300 [thread overview]
Message-ID: <5176931B.1010903@mellanox.com> (raw)
In-Reply-To: <1366657270.16391.87.camel@edumazet-glaptop>
On 22/04/2013 22:01, Eric Dumazet wrote:
> On Mon, 2013-04-22 at 14:56 +0300, Amir Vadai wrote:
>> Add a service task to run tasks that needed to be executed periodically.
>> Currently the only task is a watchdog to catch NIC clock overflow, to make
>> timestamping accurate.
>> Will move the statistics task into this framework in a later patch.
>>
>> Signed-off-by: Amir Vadai <amirv@mellanox•com>
>> ---
>> drivers/net/ethernet/mellanox/mlx4/en_clock.c | 20 ++++++++++++++++++++
>> drivers/net/ethernet/mellanox/mlx4/en_netdev.c | 24 ++++++++++++++++++++++++
>> drivers/net/ethernet/mellanox/mlx4/mlx4_en.h | 4 ++++
>> 3 files changed, 48 insertions(+), 0 deletions(-)
>>
>> diff --git a/drivers/net/ethernet/mellanox/mlx4/en_clock.c b/drivers/net/ethernet/mellanox/mlx4/en_clock.c
>> index 6d8227d..c1982a4 100644
>> --- a/drivers/net/ethernet/mellanox/mlx4/en_clock.c
>> +++ b/drivers/net/ethernet/mellanox/mlx4/en_clock.c
>> @@ -126,4 +126,24 @@ void mlx4_en_init_timestamp(struct mlx4_en_dev *mdev)
>>
>> timecounter_init(&mdev->clock, &mdev->cycles,
>> ktime_to_ns(ktime_get_real()));
>> +
>> + /* Calculate period in seconds to call the overflow watchdog. Doing
>> + * that, by dividing the maximal cycles value in nano-seconds, convert
>> + * it to seconds, and divide by 2 - to make sure counter is checked at
>> + * least once every wrap around.
>> + */
>> + mdev->overflow_period =
>> + cyclecounter_cyc2ns(&mdev->cycles,
>> + mdev->cycles.mask) / 1000000 / 2;
>> +}
>> +
>
> So this 1000000 looks like NSEC_PER_SEC/HZ ?
No. It is just a typo - used 10^6 instead of 10^9 for nano's.
But it is a good idea to have the HZ multiplied in the initialization of
overflow_period - will fix the calculation and change overflow_period
units to be jiffies, and not seconds.
>
> What if HZ=100 ?
>
>
>
Thanks,
Amir
prev parent reply other threads:[~2013-04-23 13:56 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-04-22 11:56 [PATCH net-next V2 0/5] net/mlx4: HW timestamping support Amir Vadai
2013-04-22 11:56 ` [PATCH net-next V2 1/5] net/mlx4_core: Add timestamping device capability Amir Vadai
2013-04-22 17:10 ` Sergei Shtylyov
2013-04-23 7:01 ` Amir Vadai
2013-04-22 11:56 ` [PATCH net-next V2 2/5] net/mlx4_core: Read HCA frequency and map internal clock Amir Vadai
2013-04-22 11:56 ` [PATCH net-next V2 3/5] net/mlx4_en: Add HW timestamping (TS) support Amir Vadai
2013-04-22 11:56 ` [PATCH net-next V2 4/5] net/mlx4_en: Support software timestamping Amir Vadai
2013-04-22 11:56 ` [PATCH net-next V2 5/5] net/mlx4_en: Add a service task Amir Vadai
2013-04-22 19:01 ` Eric Dumazet
2013-04-23 13:56 ` Amir Vadai [this message]
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