From: Andi Kleen <ak@suse.de>
To: Steve Modica <modica@sgi.com>
Cc: netdev@oss.sgi.com
Subject: Re: do_gettimeofday
Date: Thu, 2 Oct 2003 21:29:42 +0200 [thread overview]
Message-ID: <20031002192942.GB29673@wotan.suse.de> (raw)
In-Reply-To: <3F7C6F3B.6070502@sgi.com>
On Thu, Oct 02, 2003 at 01:32:27PM -0500, Steve Modica wrote:
> We've been doing some experiments here with large numbers of adapters on a
> 64p Linux system.
> When running 8 threads and 8 cpus, the do_gettimeofday code starts to use a
> lot of time.
That's a known problem. The funny thing is that the only users
of this time stamp is SO_TIMESTAMP, which is rarely used (except tcpdump)
and something in DECnet. IMHO the right fix is to add a global
counter that counts all all sockets that use SO_TIMESTAMP and when it's
zero never call it. Decnet could be probably fixed to just use jiffies
like TCP does.
Drawback is that when you enable SO_TIMESTAMP there is a small time window
when the packets are not time stamped yet. The socket layer can just fill
in the current time though.
-Andi
next prev parent reply other threads:[~2003-10-02 19:29 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-10-02 18:32 do_gettimeofday Steve Modica
2003-10-02 19:29 ` Andi Kleen [this message]
2003-10-02 19:56 ` do_gettimeofday Stephen Hemminger
2003-10-02 20:46 ` do_gettimeofday Mitchell Blank Jr
2003-10-03 7:41 ` do_gettimeofday David S. Miller
2003-10-03 8:26 ` do_gettimeofday Mitchell Blank Jr
2003-10-03 8:27 ` do_gettimeofday David S. Miller
2003-10-03 8:48 ` do_gettimeofday Mitchell Blank Jr
2003-10-03 8:52 ` do_gettimeofday David S. Miller
2003-10-03 9:26 ` do_gettimeofday Mitchell Blank Jr
2003-10-03 9:23 ` do_gettimeofday David S. Miller
2003-10-03 16:42 ` do_gettimeofday Ben Greear
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=20031002192942.GB29673@wotan.suse.de \
--to=ak@suse.de \
--cc=modica@sgi.com \
--cc=netdev@oss.sgi.com \
/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).