From: Andi Kleen <ak@muc.de>
To: "David S. Miller" <davem@davemloft.net>
Cc: netdev@oss.sgi.com
Subject: Re: issue with new TCP TSO stuff
Date: Thu, 12 May 2005 16:13:05 +0200 [thread overview]
Message-ID: <m1sm0sttvy.fsf@muc.de> (raw)
In-Reply-To: <20050511.223036.39664020.davem@davemloft.net> (David S. Miller's message of "Wed, 11 May 2005 22:30:36 -0700 (PDT)")
"David S. Miller" <davem@davemloft.net> writes:
>
> This shows up in testing where the connection is application limited.
> For example, an "scp" goes more slowly over TSO now, there are less
> cpu cycles available for the encryption.
>
> It's tricky to come up with a scheme to fix this. I would love to be
> able to not do the page grabs/releases in the actual TSO frame. I
> really haven't come up with a clean way to do that however.
Are you sure a few atomic_inc/dec are really causing noticeable
slowdown? That would surprise me unless you have lots of cache line
bouncing on a MP system.
What CPU did you test it on? Does it happen with only a single CPU?
And did you actually see them in some profile?
Assuming the struct page is in cache the P4 core is the slowest at
that that I know, but even on that one it should be in the noise on
the other overhead of talking to a NIC on a PCI bus.
Perhaps it is something else..
-Andi
next prev parent reply other threads:[~2005-05-12 14:13 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-05-12 5:30 issue with new TCP TSO stuff David S. Miller
2005-05-12 10:05 ` Herbert Xu
2005-05-12 20:13 ` David S. Miller
2005-05-12 21:47 ` Herbert Xu
2005-05-12 22:10 ` Herbert Xu
2005-05-12 22:52 ` David S. Miller
2005-05-12 23:10 ` Herbert Xu
2005-05-12 23:24 ` David S. Miller
2005-05-12 23:52 ` Herbert Xu
2005-05-13 4:36 ` David S. Miller
2005-05-13 13:25 ` Herbert Xu
2005-05-12 22:46 ` David S. Miller
2005-05-12 14:13 ` Andi Kleen [this message]
2005-05-12 19:26 ` David S. Miller
[not found] ` <20050512200251.GA72662@muc.de>
2005-05-12 20:03 ` David S. Miller
2005-05-12 20:26 ` Andi Kleen
2005-05-12 22:34 ` David S. Miller
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