From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: David Laight <David.Laight@ACULAB.COM>
Cc: netdev@vger.kernel.org,
Yevgeny Petrilin <yevgenyp@mellanox.co.il>,
Eli Cohen <eli@mellanox.co.il>,
Eli Cohen <eli@dev.mellanox.co.il>,
linuxppc-dev@lists.ozlabs.org,
Thadeu Lima de Souza Cascardo <cascardo@linux.vnet.ibm.com>
Subject: RE: [PATCH] mlx4_en: fix transmit of packages when blue frame isenabled
Date: Sun, 09 Oct 2011 09:28:51 +0200 [thread overview]
Message-ID: <1318145331.29415.372.camel@pasglop> (raw)
In-Reply-To: <AE90C24D6B3A694183C094C60CF0A2F6D8AE76@saturn3.aculab.com>
On Thu, 2011-10-06 at 15:10 +0100, David Laight wrote:
> horrid...
> 1) I'm not sure the caller expects the buffer to be corrupted.
> 2) It contains a lot of memory cycles.
> 3) It looked from the calls that this code is copying descriptors,
> so the transfer length is probably 1 or 2 words - so the loop
> is inefficient.
> 4) ppc doesn't have a fast byteswap instruction (very new gcc might
> use the byteswapping memery access for the le32_to_cpu() though),
> so it would be better getting the byteswap done inside
> __iowrite64_copy() - since that is probably requesting a byteswap
> anyway.
> OTOH I'm not at all clear about the 64bit xfers....
And it's just plain wrong anyway. You should never have to byteswap a
copy.
Ben.
WARNING: multiple messages have this Message-ID (diff)
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: David Laight <David.Laight@ACULAB.COM>
Cc: Eli Cohen <eli@dev.mellanox.co.il>,
Thadeu Lima de Souza Cascardo <cascardo@linux.vnet.ibm.com>,
Eli Cohen <eli@mellanox.co.il>,
Yevgeny Petrilin <yevgenyp@mellanox.co.il>,
linuxppc-dev@lists.ozlabs.org, netdev@vger.kernel.org
Subject: RE: [PATCH] mlx4_en: fix transmit of packages when blue frame isenabled
Date: Sun, 09 Oct 2011 09:28:51 +0200 [thread overview]
Message-ID: <1318145331.29415.372.camel@pasglop> (raw)
In-Reply-To: <AE90C24D6B3A694183C094C60CF0A2F6D8AE76@saturn3.aculab.com>
On Thu, 2011-10-06 at 15:10 +0100, David Laight wrote:
> horrid...
> 1) I'm not sure the caller expects the buffer to be corrupted.
> 2) It contains a lot of memory cycles.
> 3) It looked from the calls that this code is copying descriptors,
> so the transfer length is probably 1 or 2 words - so the loop
> is inefficient.
> 4) ppc doesn't have a fast byteswap instruction (very new gcc might
> use the byteswapping memery access for the le32_to_cpu() though),
> so it would be better getting the byteswap done inside
> __iowrite64_copy() - since that is probably requesting a byteswap
> anyway.
> OTOH I'm not at all clear about the 64bit xfers....
And it's just plain wrong anyway. You should never have to byteswap a
copy.
Ben.
next prev parent reply other threads:[~2011-10-09 7:29 UTC|newest]
Thread overview: 65+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-09-30 13:23 [PATCH] mlx4_en: fix transmit of packages when blue frame is enabled Thadeu Lima de Souza Cascardo
2011-10-02 8:58 ` Yevgeny Petrilin
2011-10-03 14:37 ` Thadeu Lima de Souza Cascardo
2011-10-03 14:56 ` Yevgeny Petrilin
2011-10-03 20:53 ` Thadeu Lima de Souza Cascardo
2011-10-03 20:53 ` Thadeu Lima de Souza Cascardo
2011-10-04 6:02 ` Benjamin Herrenschmidt
2011-10-04 6:02 ` Benjamin Herrenschmidt
2011-10-04 20:26 ` Thadeu Lima de Souza Cascardo
2011-10-04 20:26 ` Thadeu Lima de Souza Cascardo
2011-10-05 8:15 ` Eli Cohen
2011-10-05 8:15 ` Eli Cohen
2011-10-06 13:57 ` Eli Cohen
2011-10-06 13:57 ` Eli Cohen
2011-10-06 14:10 ` [PATCH] mlx4_en: fix transmit of packages when blue frame isenabled David Laight
2011-10-06 14:10 ` David Laight
2011-10-07 22:29 ` Thadeu Lima de Souza Cascardo
2011-10-07 22:29 ` Thadeu Lima de Souza Cascardo
2011-10-09 7:28 ` Benjamin Herrenschmidt [this message]
2011-10-09 7:28 ` Benjamin Herrenschmidt
2011-10-09 7:25 ` [PATCH] mlx4_en: fix transmit of packages when blue frame is enabled Benjamin Herrenschmidt
2011-10-09 7:25 ` Benjamin Herrenschmidt
2011-10-09 7:35 ` Eli Cohen
2011-10-09 7:35 ` Eli Cohen
2011-10-09 8:00 ` Benjamin Herrenschmidt
2011-10-09 8:07 ` Eli Cohen
2011-10-09 8:07 ` Eli Cohen
2011-10-09 8:38 ` Benjamin Herrenschmidt
2011-10-09 8:38 ` Benjamin Herrenschmidt
2011-10-09 9:21 ` Eli Cohen
2011-10-09 9:21 ` Eli Cohen
2011-10-09 9:52 ` Benjamin Herrenschmidt
2011-10-09 9:52 ` Benjamin Herrenschmidt
2011-10-09 10:30 ` Eli Cohen
2011-10-09 10:30 ` Eli Cohen
2011-10-10 7:32 ` Benjamin Herrenschmidt
2011-10-10 7:32 ` Benjamin Herrenschmidt
2011-10-10 16:42 ` [PATCH] mlx4_en: fix endianness with blue frame support Thadeu Lima de Souza Cascardo
2011-10-10 16:42 ` Thadeu Lima de Souza Cascardo
2011-10-10 16:46 ` Thadeu Lima de Souza Cascardo
2011-10-10 16:46 ` Thadeu Lima de Souza Cascardo
2011-10-10 18:10 ` David Miller
2011-10-10 18:10 ` David Miller
2011-10-10 8:20 ` [PATCH] mlx4_en: fix transmit of packages when blue frame is enabled David Laight
2011-10-10 8:20 ` David Laight
2011-10-10 8:29 ` Benjamin Herrenschmidt
2011-10-10 8:29 ` Benjamin Herrenschmidt
2011-10-10 8:40 ` David Laight
2011-10-10 8:40 ` David Laight
2011-10-10 8:47 ` Eli Cohen
2011-10-10 9:01 ` Benjamin Herrenschmidt
2011-10-10 9:01 ` Benjamin Herrenschmidt
2011-10-10 9:16 ` Eli Cohen
2011-10-10 9:16 ` Eli Cohen
2011-10-10 9:24 ` Benjamin Herrenschmidt
2011-10-10 9:24 ` Benjamin Herrenschmidt
2011-10-10 9:29 ` Eli Cohen
2011-10-10 9:29 ` Eli Cohen
2011-10-10 10:18 ` Benjamin Herrenschmidt
2011-10-10 10:18 ` Benjamin Herrenschmidt
2011-10-10 8:53 ` Benjamin Herrenschmidt
2011-10-10 8:53 ` Benjamin Herrenschmidt
2011-10-09 7:21 ` Benjamin Herrenschmidt
2011-10-09 7:21 ` Benjamin Herrenschmidt
2011-10-09 7:19 ` Benjamin Herrenschmidt
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