From: William Allen Simpson <william.allen.simpson@gmail.com>
To: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Linux Kernel Developers <linux-kernel@vger.kernel.org>,
Linux Kernel Network Developers <netdev@vger.kernel.org>
Subject: Re: [net-next-2.6 PATCH RFC] TCPCT part 1d: generate Responder Cookie
Date: Mon, 02 Nov 2009 07:36:10 -0500 [thread overview]
Message-ID: <4AEED23A.7070009@gmail.com> (raw)
In-Reply-To: <4AEEBAC6.7020308@gmail.com>
Eric Dumazet wrote:
> cookie_hash() runs in a non preemptable context. CPU cannot change under us.
>
> (or else, we would not use __get_cpu_var(ipv4_cookie_scratch); )
>
> And of course, each cpu gets its own scratch area, thanks to __get_cpu_var()
>
Interesting. I'm not sure that running CPU intensive functions like SHA1 in
a non-preemptable context is a good idea. I'd assumed it wasn't!
Perhaps you could point at the documentation in the code that explains this?
Perhaps a function header comment that mentions it?
All I know is (from testing) that the tcp_minisockets.c caller is sometimes
called in a fashion that requires atomic allocation, and other times does not!
See my "Subject: query: tcpdump versus atomic?" thread from Oct 14th.
next prev parent reply other threads:[~2009-11-02 12:36 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-10-30 11:00 [net-next-2.6 PATCH RFC] TCPCT part 1d: generate Responder Cookie William Allen Simpson
2009-10-30 18:11 ` William Allen Simpson
2009-11-01 13:01 ` William Allen Simpson
2009-11-01 18:03 ` Eric Dumazet
2009-11-02 10:39 ` William Allen Simpson
2009-11-02 10:50 ` David Miller
2009-11-02 10:56 ` Eric Dumazet
2009-11-02 12:36 ` William Allen Simpson [this message]
2009-11-02 13:16 ` Eric Dumazet
2009-11-02 17:21 ` William Allen Simpson
2009-11-02 17:42 ` Eric Dumazet
2009-11-03 22:38 ` William Allen Simpson
2009-11-03 23:03 ` Eric Dumazet
2009-11-04 21:48 ` Paul E. McKenney
2009-11-05 12:17 ` William Allen Simpson
2009-11-05 12:45 ` William Allen Simpson
2009-11-05 13:34 ` Eric Dumazet
2009-11-05 13:19 ` Eric Dumazet
2009-11-05 19:44 ` William Allen Simpson
2009-11-05 14:59 ` Paul E. McKenney
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=4AEED23A.7070009@gmail.com \
--to=william.allen.simpson@gmail.com \
--cc=eric.dumazet@gmail.com \
--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).