From: christophe leroy <christophe.leroy@c-s.fr>
To: Herbert Xu <herbert@gondor.apana.org.au>
Cc: netdev <netdev@vger.kernel.org>, "David S. Miller" <davem@davemloft.net>
Subject: Performance loss due to commit 37c3185 ([NET]: Added GSO toggle)
Date: Sat, 20 Jun 2015 11:55:03 +0200 [thread overview]
Message-ID: <55853877.9080000@c-s.fr> (raw)
Hello Herbert,
In commit "[NET]: Added GSO toggle"
37c3185a02d4b85fbe134bf5204535405dd2c957,
you force NETIF_F_HW_CSUM if GSO feature is selected.
By default, SW GSO is active as soon as a network board has NETIF_F_SG
feature.
This means that function sk_setup_caps() forces NETIF_F_HW_CSUM for any
board having NETIF_F_SG
For boards having no HW checksum capability, this results in performance
loss due to data copy being done in skb_do_copy_data_nocache() with
copy_from_user() then checksum being done later with csum_partial()
instead of getting both done at the same time using
csum_and_copy_from_user()
Is there a reason for forcing NETIF_F_HW_CSUM ?
Christophe
---
L'absence de virus dans ce courrier électronique a été vérifiée par le logiciel antivirus Avast.
https://www.avast.com/antivirus
next reply other threads:[~2015-06-20 10:32 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-06-20 9:55 christophe leroy [this message]
2015-06-25 14:37 ` Performance loss due to commit 37c3185 ([NET]: Added GSO toggle) Herbert Xu
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=55853877.9080000@c-s.fr \
--to=christophe.leroy@c-s.fr \
--cc=davem@davemloft.net \
--cc=herbert@gondor.apana.org.au \
--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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.