From: Rick Jones <rick.jones2@hp.com>
To: Linas Vepstas <linas@austin.ibm.com>
Cc: akpm@osdl.org, Arnd Bergmann <arnd@arndb.de>,
jeff@garzik.org, netdev@vger.kernel.org, jklewis@us.ibm.com,
linux-kernel@vger.kernel.org, linuxppc-dev@ozlabs.org,
Jens.Osterkamp@de.ibm.com, David Miller <davem@davemloft.net>
Subject: Re: [PATCH 1/2]: powerpc/cell spidernet bottom half
Date: Wed, 16 Aug 2006 16:08:34 -0700 [thread overview]
Message-ID: <44E3A572.20600@hp.com> (raw)
In-Reply-To: <20060816225558.GM20551@austin.ibm.com>
Linas Vepstas wrote:
> On Wed, Aug 16, 2006 at 11:24:46PM +0200, Arnd Bergmann wrote:
>
>>it only
>>seems to be hard to make it go fast using any of them.
>
>
> Last round of measurements seemed linear for packet sizes between
> 60 and 600 bytes, suggesting that the hardware can handle a
> maximum of 120K descriptors/second, independent of packet size.
> I don't know why this is.
DMA overhead perhaps? If it takes so many micro/nanoseconds to get a
DMA going.... That used to be a reason the Tigon2 had such low PPS
rates and issues with multiple buffer packets and a 1500 byte MTU - it
had rather high DMA setup latency, and then if you put it into a system
with highish DMA read/write latency... well that didn't make it any
better :)
rick jones
WARNING: multiple messages have this Message-ID (diff)
From: Rick Jones <rick.jones2@hp.com>
To: Linas Vepstas <linas@austin.ibm.com>
Cc: Arnd Bergmann <arnd@arndb.de>, David Miller <davem@davemloft.net>,
jeff@garzik.org, netdev@vger.kernel.org,
linux-kernel@vger.kernel.org, linuxppc-dev@ozlabs.org,
jklewis@us.ibm.com, Jens.Osterkamp@de.ibm.com, akpm@osdl.org
Subject: Re: [PATCH 1/2]: powerpc/cell spidernet bottom half
Date: Wed, 16 Aug 2006 16:08:34 -0700 [thread overview]
Message-ID: <44E3A572.20600@hp.com> (raw)
In-Reply-To: <20060816225558.GM20551@austin.ibm.com>
Linas Vepstas wrote:
> On Wed, Aug 16, 2006 at 11:24:46PM +0200, Arnd Bergmann wrote:
>
>>it only
>>seems to be hard to make it go fast using any of them.
>
>
> Last round of measurements seemed linear for packet sizes between
> 60 and 600 bytes, suggesting that the hardware can handle a
> maximum of 120K descriptors/second, independent of packet size.
> I don't know why this is.
DMA overhead perhaps? If it takes so many micro/nanoseconds to get a
DMA going.... That used to be a reason the Tigon2 had such low PPS
rates and issues with multiple buffer packets and a 1500 byte MTU - it
had rather high DMA setup latency, and then if you put it into a system
with highish DMA read/write latency... well that didn't make it any
better :)
rick jones
next prev parent reply other threads:[~2006-08-16 23:20 UTC|newest]
Thread overview: 91+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-08-11 17:03 [PATCH 0/4]: powerpc/cell spidernet ethernet driver fixes Linas Vepstas
2006-08-11 17:03 ` Linas Vepstas
2006-08-11 17:06 ` [PATCH 1/4]: powerpc/cell spidernet burst alignment patch Linas Vepstas
2006-08-11 17:06 ` Linas Vepstas
2006-08-11 17:08 ` [PATCH 2/4]: powerpc/cell spidernet low watermark patch Linas Vepstas
2006-08-11 17:08 ` Linas Vepstas
2006-08-16 23:43 ` Benjamin Herrenschmidt
2006-08-16 23:43 ` Benjamin Herrenschmidt
2006-08-18 19:23 ` Linas Vepstas
2006-08-18 19:23 ` Linas Vepstas
2006-08-18 21:25 ` David Miller
2006-08-18 21:25 ` David Miller
2006-08-18 22:46 ` Linas Vepstas
2006-08-18 22:46 ` Linas Vepstas
2006-08-18 22:51 ` David Miller
2006-08-18 22:51 ` David Miller
2006-08-18 23:29 ` Linas Vepstas
2006-08-18 23:29 ` Linas Vepstas
2006-08-18 23:45 ` Linas Vepstas
2006-08-18 23:45 ` Linas Vepstas
2006-08-19 4:33 ` Benjamin Herrenschmidt
2006-08-19 4:33 ` Benjamin Herrenschmidt
2006-08-22 0:13 ` Linas Vepstas
2006-08-22 0:13 ` Linas Vepstas
2006-08-22 0:30 ` David Miller
2006-08-22 0:30 ` David Miller
2006-08-19 4:31 ` Benjamin Herrenschmidt
2006-08-19 4:31 ` Benjamin Herrenschmidt
2006-08-11 17:09 ` [PATCH 3/4]: powerpc/cell spidernet stop error printing patch Linas Vepstas
2006-08-11 17:09 ` Linas Vepstas
2006-08-11 17:11 ` [PATCH 4/4]: powerpc/cell spidernet ethtool -i version number info Linas Vepstas
2006-08-11 17:11 ` Linas Vepstas
2006-08-11 18:00 ` Olof Johansson
2006-08-11 18:00 ` Olof Johansson
2006-08-11 18:50 ` James K Lewis
2006-08-11 18:50 ` James K Lewis
2006-08-11 19:46 ` Linas Vepstas
2006-08-11 19:46 ` Linas Vepstas
2006-08-15 19:05 ` Olof Johansson
2006-08-15 19:05 ` Olof Johansson
2006-08-16 0:29 ` Michael Ellerman
2006-08-16 0:29 ` Michael Ellerman
2006-08-11 17:42 ` [PATCH 0/4]: powerpc/cell spidernet ethernet driver fixes jschopp
2006-08-11 17:42 ` jschopp
2006-08-11 17:44 ` Sam Ravnborg
2006-08-11 17:44 ` Sam Ravnborg
2006-08-11 19:31 ` Linas Vepstas
2006-08-11 19:31 ` Linas Vepstas
2006-08-11 20:27 ` Arnd Bergmann
2006-08-11 20:27 ` Arnd Bergmann
2006-08-16 16:18 ` [PATCH 1/2]: powerpc/cell spidernet bottom half Linas Vepstas
2006-08-16 16:18 ` Linas Vepstas
2006-08-16 16:30 ` Jeff Garzik
2006-08-16 16:30 ` Jeff Garzik
2006-08-16 20:30 ` Linas Vepstas
2006-08-16 20:30 ` Linas Vepstas
2006-08-16 20:34 ` Jeff Garzik
2006-08-16 20:34 ` Jeff Garzik
2006-08-16 20:46 ` David Miller
2006-08-16 20:46 ` David Miller
2006-08-16 21:24 ` Arnd Bergmann
2006-08-16 21:24 ` Arnd Bergmann
2006-08-16 21:24 ` Arnd Bergmann
2006-08-16 21:32 ` David Miller
2006-08-16 21:32 ` David Miller
2006-08-16 22:16 ` Arnd Bergmann
2006-08-16 22:16 ` Arnd Bergmann
2006-08-16 22:16 ` Arnd Bergmann
2006-08-16 22:29 ` David Miller
2006-08-16 22:29 ` David Miller
2006-08-16 22:47 ` Arnd Bergmann
2006-08-16 22:47 ` Arnd Bergmann
2006-08-16 23:30 ` Linas Vepstas
2006-08-16 23:30 ` Linas Vepstas
2006-08-16 23:32 ` David Miller
2006-08-16 23:32 ` David Miller
2006-08-17 0:23 ` Linas Vepstas
2006-08-17 0:23 ` Linas Vepstas
2006-08-16 23:24 ` Linas Vepstas
2006-08-16 23:24 ` Linas Vepstas
2006-08-16 22:55 ` Linas Vepstas
2006-08-16 22:55 ` Linas Vepstas
2006-08-16 23:03 ` Arnd Bergmann
2006-08-16 23:03 ` Arnd Bergmann
2006-08-16 23:47 ` Linas Vepstas
2006-08-16 23:47 ` Linas Vepstas
2006-08-16 23:08 ` Rick Jones [this message]
2006-08-16 23:08 ` Rick Jones
2006-08-16 21:58 ` Linas Vepstas
2006-08-16 21:58 ` Linas Vepstas
2006-08-16 16:23 ` [PATCH 2/2]: powerpc/cell spidernet refine locking Linas Vepstas
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