netdev - Re: [PATCH net-next V2 5/5] net/mlx4

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <5176931B.1010903@mellanox.com>
Date:	Tue, 23 Apr 2013 16:56:43 +0300
From:	Amir Vadai <amirv@...lanox.com>
To:	Eric Dumazet <eric.dumazet@...il.com>
CC:	"David S. Miller" <davem@...emloft.net>, <netdev@...r.kernel.org>,
	Richard Cochran <richardcochran@...il.com>,
	Or Gerlitz <ogerlitz@...lanox.com>,
	Eugenia Emantayev <eugenia@...lanox.com>
Subject: Re: [PATCH net-next V2 5/5] net/mlx4_en: Add a service task

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@...lanox.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
--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html