From: Hadar Hen Zion <hadarh@mellanox•com>
To: Richard Cochran <richardcochran@gmail•com>
Cc: Shawn Bohrer <shawn.bohrer@gmail•com>,
"David S. Miller" <davem@davemloft•net>,
Or Gerlitz <ogerlitz@mellanox•com>,
Amir Vadai <amirv@mellanox•com>, <netdev@vger•kernel.org>,
<tomk@rgmadvisors•com>, Shawn Bohrer <sbohrer@rgmadvisors•com>
Subject: Re: [PATCH net-next 1/2] mlx4_en: Add PTP hardware clock
Date: Tue, 24 Dec 2013 15:58:06 +0200 [thread overview]
Message-ID: <52B992EE.5030401@mellanox.com> (raw)
In-Reply-To: <20131223184845.GA4922@netboy>
On 12/23/2013 8:48 PM, Richard Cochran wrote:
> On Sun, Dec 22, 2013 at 03:13:12PM +0200, Hadar Hen Zion wrote:
>
>> 2. Adding spin lock in the data path reduce performance by 15% when
>> HW timestamping is enabled. I did some testing and replacing
>> spin_lock_irqsave with read/write_lock_irqsave prevents the
>> performance decrease.
>
> Why do the spin locks cause such a bottleneck?
>
> Is there really that much lock contention in your test?
>
> Your figure of 15% seems awfully high. How did you arrive at that
> figure?
>
> Thanks,
> Richard
>
The spin locks case such a bottleneck since I'm using multiple streams
in my performance test. RSS mechanism scattered the streams between
multiple RX rings while each RX ring is bound to a different cup.
The describe scenario cause lock contention between the different RX rings.
Performance drops from 37.8 Gbits/sec to 32.1 Gbits/sec when spin locks
are added and goes back to 37.8 Gbits/sec when using read/write locks.
Thanks,
Hadar
next prev parent reply other threads:[~2013-12-24 13:58 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 [this message]
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
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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