netdev - Re: limited network bandwidth with 3.2.x kernels

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CADVnQykm==YJZbdCbLxgJ236jD2yN0xT99gmeYX-FGnyBvfEGA@mail.gmail.com>
Date:	Thu, 16 Feb 2012 12:22:29 -0500
From:	Neal Cardwell <ncardwell@...gle.com>
To:	David Miller <davem@...emloft.net>
Cc:	eric.dumazet@...il.com, bhutchings@...arflare.com,
	netdev@...r.kernel.org, alekcejk@...glemail.com
Subject: Re: limited network bandwidth with 3.2.x kernels

Our team has also run into issues with GRO/LRO "stretch ACKs", and
their negative impact on TCP performance. We have a patch that we've
been working with that deals with the sender-side issues. It turns out
that neither the ABC nor non-ABC byte counting quite fixes the stretch
ACKs issues.

On the receiver side, the approach of changing tcp_grow_window() and
__tcp_grow_window() to adjust things in terms of actual packet size
rather than a fixed 2*MSS sounds great to me as well.

In terms of the original 3.1 vs 3.2 issue report that started this
thread, I didn't see any evidence of LRO or GRO causing stretch ACKs.
(Alexey, would you be able to confim by running "ethtool -k eth0" on
both kernels?) So it seems that probably the original issue is
unrelated to stretch ACKs?

neal
--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html