From: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
To: Willy Tarreau <w@1wt.eu>
Cc: Rob Herring <rob.herring@calxeda.com>,
Arnaud Ebalard <arno@natisbad.org>,
Florian Fainelli <f.fainelli@gmail.com>,
simon.guinot@sequanux.org, Eric Dumazet <eric.dumazet@gmail.com>,
netdev@vger.kernel.org, edumazet@google.com,
Cong Wang <xiyou.wangcong@gmail.com>,
linux-arm-kernel@lists.infradead.org
Subject: Re: ARM network performance and dma_mask (was: [BUG,REGRESSION?] 3.11.6+,3.12: GbE iface rate drops to few KB/s)
Date: Thu, 21 Nov 2013 20:04:33 +0100 [thread overview]
Message-ID: <20131121200433.4cb97d9e@skate> (raw)
In-Reply-To: <20131121183834.GB18513@1wt.eu>
Dear Willy Tarreau,
On Thu, 21 Nov 2013 19:38:34 +0100, Willy Tarreau wrote:
> While we were diagnosing a network performance regression that we finally
> found and fixed, it appeared during a test that Linus' tree shows a much
> higher performance on Armada 370 (armv7) than its predecessors. I can
> saturate the two Gig links of my Mirabox each with a single TCP flow and
> keep up to 25% of idle CPU in the optimal case. In 3.12.1 or 3.10.20, I
> can achieve around 1.3 Gbps when the two ports are used in parallel.
Interesting finding and analysis, once again!
> I'm not at ease with these things so I'd like to ask your opinion here, is
> this supposed to be an improvement or a fix ? Is this something we should
> backport into stable versions, or is there something to fix in the armada
> platform so that it works just as if the patch was applied ?
I guess the driver should have been setting its dma_mask to 0xffffffff,
since the platform is capable of doing DMA on the first 32 bits of the
physical address space, probably something like calling
pci_set_dma_mask(pdev, DMA_BIT_MASK(32)) or something like that. I know
Russell has recently added some helpers to prevent stupid people (like
me) from doing mistakes when setting the DMA masks. Certainly worth
having a look.
Best regards,
Thomas
--
Thomas Petazzoni, CTO, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com
next prev parent reply other threads:[~2013-11-21 19:04 UTC|newest]
Thread overview: 67+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-11-10 13:53 [BUG,REGRESSION?] 3.11.6+,3.12: GbE iface rate drops to few KB/s Arnaud Ebalard
2013-11-12 6:48 ` Cong Wang
2013-11-12 7:56 ` Arnaud Ebalard
2013-11-12 8:36 ` Willy Tarreau
2013-11-12 9:14 ` Arnaud Ebalard
2013-11-12 10:01 ` Willy Tarreau
2013-11-12 15:34 ` Arnaud Ebalard
2013-11-13 7:22 ` Willy Tarreau
2013-11-17 14:19 ` Willy Tarreau
2013-11-17 17:41 ` Eric Dumazet
2013-11-19 6:44 ` Arnaud Ebalard
2013-11-19 13:53 ` Eric Dumazet
2013-11-19 17:43 ` Willy Tarreau
2013-11-19 18:31 ` Eric Dumazet
2013-11-19 18:41 ` Willy Tarreau
2013-11-19 23:53 ` Arnaud Ebalard
2013-11-20 0:08 ` Eric Dumazet
2013-11-20 0:35 ` Willy Tarreau
2013-11-20 0:43 ` Eric Dumazet
2013-11-20 0:52 ` Willy Tarreau
2013-11-20 8:50 ` Thomas Petazzoni
2013-11-20 19:11 ` Willy Tarreau
2013-11-20 19:26 ` Arnaud Ebalard
2013-11-20 21:28 ` Arnaud Ebalard
2013-11-20 21:54 ` Willy Tarreau
2013-11-21 0:44 ` Willy Tarreau
2013-11-21 18:38 ` ARM network performance and dma_mask (was: [BUG,REGRESSION?] 3.11.6+,3.12: GbE iface rate drops to few KB/s) Willy Tarreau
2013-11-21 19:04 ` Thomas Petazzoni [this message]
2013-11-21 21:51 ` Willy Tarreau
2013-11-21 22:01 ` ARM network performance and dma_mask Rob Herring
2013-11-21 22:13 ` Willy Tarreau
2013-11-21 21:51 ` [BUG,REGRESSION?] 3.11.6+,3.12: GbE iface rate drops to few KB/s Arnaud Ebalard
2013-11-21 21:52 ` Willy Tarreau
2013-11-21 22:00 ` Eric Dumazet
2013-11-21 22:55 ` Arnaud Ebalard
2013-11-21 23:23 ` Rick Jones
2013-11-20 17:12 ` Willy Tarreau
2013-11-20 17:30 ` Eric Dumazet
2013-11-20 17:38 ` Willy Tarreau
2013-11-20 18:52 ` David Miller
2013-11-20 17:34 ` Willy Tarreau
2013-11-20 17:40 ` Eric Dumazet
2013-11-20 18:15 ` Willy Tarreau
2013-11-20 18:21 ` Eric Dumazet
2013-11-20 18:29 ` Willy Tarreau
2013-11-20 19:22 ` Arnaud Ebalard
2013-11-18 10:09 ` David Laight
2013-11-18 10:52 ` Willy Tarreau
2013-11-18 10:26 ` Thomas Petazzoni
2013-11-18 10:44 ` Simon Guinot
2013-11-18 16:54 ` Stephen Hemminger
2013-11-18 17:13 ` Eric Dumazet
2013-11-18 10:51 ` Willy Tarreau
2013-11-18 17:58 ` Florian Fainelli
2013-11-12 14:39 ` [PATCH] tcp: tsq: restore minimal amount of queueing Eric Dumazet
2013-11-12 15:24 ` Sujith Manoharan
2013-11-13 14:06 ` Eric Dumazet
2013-11-13 14:32 ` [PATCH v2] " Eric Dumazet
2013-11-13 21:18 ` Arnaud Ebalard
2013-11-13 21:59 ` Holger Hoffstaette
2013-11-13 23:40 ` Eric Dumazet
2013-11-13 23:52 ` Holger Hoffstaette
2013-11-17 23:15 ` Francois Romieu
2013-11-18 16:26 ` Holger Hoffstätte
2013-11-18 16:47 ` Eric Dumazet
2013-11-13 22:41 ` Eric Dumazet
2013-11-14 21:26 ` David Miller
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