From: "Theodore Ts'o" <tytso@mit.edu>
To: "David S. Miller" <davem@redhat.com>
Cc: Andi Kleen <ak@suse.de>, linux-kernel@vger.kernel.org
Subject: Re: Fire Engine??
Date: Wed, 26 Nov 2003 15:22:16 -0500 [thread overview]
Message-ID: <20031126202216.GA13116@thunk.org> (raw)
In-Reply-To: <20031126113040.3b774360.davem@redhat.com>
On Wed, Nov 26, 2003 at 11:30:40AM -0800, David S. Miller wrote:
> > - Doing gettimeofday on each incoming packet is just dumb, especially
> > when you have gettimeofday backed with a slow southbridge timer.
> > This shows quite badly on many profile logs.
> > I still think right solution for that would be to only take time stamps
> > when there is any user for it (= no timestamps in 99% of all systems)
>
> Andi, I know this is a problem, but for the millionth time your idea
> does not work because we don't know if the user asked for the timestamp
> until we are deep within the recvmsg() processing, which is long after
> the packet has arrived.
I believe what Andi was suggesting was if there was **no** processes
that are currently requesting timestamps, then we can dispense with
taking the timestamp. If a single user asks for the timestamp, then
we would still end up taking timestamps on all packets. Is this worth
the overhead to keep track of that factor? It's arguable, but some
platforms, probably yes.
- Ted
next prev parent reply other threads:[~2003-11-26 20:22 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <BAY1-DAV15JU71pROHD000040e2@hotmail.com.suse.lists.linux.kernel>
[not found] ` <20031125183035.1c17185a.davem@redhat.com.suse.lists.linux.kernel>
2003-11-26 9:53 ` Fire Engine?? Andi Kleen
2003-11-26 11:35 ` John Bradford
2003-11-26 18:50 ` Mike Fedyk
2003-11-26 19:19 ` Diego Calleja García
2003-11-26 19:59 ` Mike Fedyk
2003-11-27 3:54 ` Bill Huey
2003-11-26 15:00 ` Trond Myklebust
2003-11-26 23:01 ` Andi Kleen
2003-11-26 23:23 ` Trond Myklebust
2003-11-26 23:38 ` Andi Kleen
2003-11-26 19:30 ` David S. Miller
2003-11-26 19:58 ` Paul Menage
2003-11-26 20:03 ` David S. Miller
2003-11-26 22:29 ` Andi Kleen
2003-11-26 22:36 ` David S. Miller
2003-11-26 22:56 ` Andi Kleen
2003-11-26 23:13 ` David S. Miller
2003-11-26 23:29 ` Andi Kleen
2003-11-26 23:41 ` Ben Greear
2003-11-27 0:01 ` Fast timestamps David S. Miller
2003-11-27 0:30 ` Mitchell Blank Jr
2003-11-27 1:57 ` Ben Greear
2003-11-26 20:01 ` Fire Engine?? Jamie Lokier
2003-11-26 20:04 ` David S. Miller
2003-11-26 21:54 ` Pekka Pietikainen
2003-11-26 20:22 ` Theodore Ts'o [this message]
2003-11-26 21:02 ` David S. Miller
2003-11-26 21:24 ` Jamie Lokier
2003-11-26 21:38 ` David S. Miller
2003-11-26 23:43 ` Jamie Lokier
2003-11-26 21:34 ` Arjan van de Ven
2003-11-26 22:58 ` Andi Kleen
2003-11-27 12:16 ` Ingo Oeser
2003-11-26 22:39 ` Andi Kleen
2003-11-26 22:46 ` David S. Miller
2003-11-26 0:15 Mr. BOFH
2003-11-26 2:30 ` David S. Miller
2003-11-26 5:41 ` Valdis.Kletnieks
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