From: Eric Dumazet <eric.dumazet@gmail.com>
To: Chris Metcalf <cmetcalf@tilera.com>
Cc: bhutchings@solarflare.com, arnd@arndb.de,
David Miller <davem@davemloft.net>,
linux-kernel@vger.kernel.org, netdev@vger.kernel.org
Subject: Re: [PATCH v9] tilegx network driver: initial support
Date: Wed, 06 Jun 2012 20:10:23 +0200 [thread overview]
Message-ID: <1339006223.26966.36.camel@edumazet-glaptop> (raw)
In-Reply-To: <201206042023.q54KNEZp003834@farm-0002.internal.tilera.com>
On Mon, 2012-06-04 at 16:12 -0400, Chris Metcalf wrote:
> This change adds support for the tilegx network driver based on the
> GXIO IORPC support in the tilegx software stack, using the on-chip
> mPIPE packet processing engine.
>
> +
> +/* Do "TSO" handling for egress.
> + *
> + * Normally drivers set NETIF_F_TSO only to support hardware TSO;
> + * otherwise the stack uses scatter-gather to implement GSO in software.
> + * On our testing, enabling GSO support (via NETIF_F_SG) drops network
> + * performance down to around 7.5 Gbps on the 10G interfaces, although
> + * also dropping cpu utilization way down, to under 8%. But
> + * implementing "TSO" in the driver brings performance back up to line
> + * rate, while dropping cpu usage even further, to less than 4%. In
> + * practice, profiling of GSO shows that skb_segment() is what causes
> + * the performance overheads; we benefit in the driver from using
> + * preallocated memory to duplicate the TCP/IP headers.
> + */
All this stuff cost about 300 lines of code in this driver, without IPv6
support.
I am pretty sure this performance problem should be solved in net/{core|
ipv4|ipv6} instead
What TCP performance do you get with TSO/GSO and SG off ?
next prev parent reply other threads:[~2012-06-06 18:10 UTC|newest]
Thread overview: 61+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-04-04 20:39 [PATCH 0/6] arch/tile: provide tilegx networking support Chris Metcalf
2012-04-04 20:39 ` [PATCH 1/6] arch/tile: introduce GXIO IORPC framework for tilegx Chris Metcalf
2012-04-04 20:58 ` [PATCH 4/6] arch/tile: common DMA code for the GXIO IORPC subsystem Chris Metcalf
2012-04-06 17:41 ` [PATCH 2/6] arch/tile: fix set_pte() to properly handle kernel MMIO mappings Chris Metcalf
2012-04-06 17:52 ` [PATCH 3/6] arch/tile: support MMIO-based readb/writeb etc Chris Metcalf
2012-04-09 13:24 ` Arnd Bergmann
2012-04-09 20:53 ` Chris Metcalf
2012-04-06 20:38 ` [PATCH 5/6] arch/tile: provide kernel support for the tilegx mPIPE shim Chris Metcalf
2012-04-09 13:34 ` Arnd Bergmann
2012-04-09 21:04 ` Chris Metcalf
2012-04-06 20:42 ` [PATCH 6/6] tilegx network driver: initial support Chris Metcalf
2012-04-09 13:49 ` Arnd Bergmann
2012-04-09 21:30 ` Chris Metcalf
2012-04-10 10:42 ` Arnd Bergmann
2012-04-12 23:23 ` Chris Metcalf
2012-04-13 10:34 ` Arnd Bergmann
2012-04-28 22:07 ` Chris Metcalf
2012-04-04 20:39 ` [PATCH v2 0/6] arch/tile: networking support for tilegx Chris Metcalf
2012-04-04 20:39 ` [PATCH v2 1/6] arch/tile: introduce GXIO IORPC framework " Chris Metcalf
2012-04-04 20:58 ` [PATCH v2 3/6] arch/tile: common DMA code for the GXIO IORPC subsystem Chris Metcalf
2012-04-06 17:52 ` [PATCH v2 2/6] arch/tile: support MMIO-based readb/writeb etc Chris Metcalf
2012-04-06 20:38 ` [PATCH v2 4/6] arch/tile: provide kernel support for the tilegx mPIPE shim Chris Metcalf
2012-04-06 20:42 ` [PATCH v2 6/6] tilegx network driver: initial support Chris Metcalf
2012-04-30 14:35 ` Arnd Bergmann
2001-09-17 4:00 ` [PATCH v3] " Chris Metcalf
2012-05-03 5:41 ` David Miller
2012-05-03 15:45 ` Chris Metcalf
2012-05-03 17:07 ` David Miller
2012-05-03 17:25 ` Chris Metcalf
2012-05-03 16:41 ` [PATCH v4] " Chris Metcalf
2012-05-04 6:42 ` David Miller
2012-05-09 10:42 ` [PATCH v5] " Chris Metcalf
2012-05-11 13:54 ` Ben Hutchings
2012-05-20 4:42 ` [PATCH v6] " Chris Metcalf
2012-05-20 20:55 ` David Miller
2012-05-23 20:42 ` [PATCH v7] " Chris Metcalf
2012-05-24 4:31 ` David Miller
2012-05-25 14:42 ` [PATCH v8] " Chris Metcalf
2012-06-04 20:12 ` [PATCH v9] " Chris Metcalf
2012-06-06 16:41 ` David Miller
2012-06-06 17:31 ` Eric Dumazet
2012-06-06 17:40 ` Eric Dumazet
2012-06-06 18:36 ` Chris Metcalf
2012-06-06 18:54 ` David Miller
2001-09-17 4:00 ` [PATCH v10] " Chris Metcalf
2012-04-06 20:42 ` Chris Metcalf
2012-06-07 20:39 ` David Miller
2012-06-07 20:44 ` Chris Metcalf
2012-06-07 20:47 ` Chris Metcalf
2012-06-07 20:50 ` Ben Hutchings
2012-06-07 20:52 ` Joe Perches
2012-06-07 20:45 ` Chris Metcalf
2012-06-12 0:03 ` David Miller
2012-06-12 13:14 ` Chris Metcalf
2012-06-06 18:10 ` Eric Dumazet [this message]
2012-06-06 18:17 ` [PATCH v9] " David Miller
2012-06-06 18:19 ` Ben Hutchings
2012-05-20 16:35 ` [PATCH v5] " Chris Metcalf
2012-04-28 19:41 ` [PATCH v2 5/6] arch/tile: break out the "csum a long" function to <asm/checksum.h> Chris Metcalf
2012-04-29 11:15 ` [PATCH 6/6] tilegx network driver: initial support Arnd Bergmann
2012-04-15 23:06 ` Chris Metcalf
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=1339006223.26966.36.camel@edumazet-glaptop \
--to=eric.dumazet@gmail.com \
--cc=arnd@arndb.de \
--cc=bhutchings@solarflare.com \
--cc=cmetcalf@tilera.com \
--cc=davem@davemloft.net \
--cc=linux-kernel@vger.kernel.org \
--cc=netdev@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).